Proc Natl Acad Sci U S A, 1977 Jan, 74(1), 44 - 8 Selective and accurate transcription of the Xenopus laevis 5S RNA genes in isolated chromatin by purified RNA polymerase III; Parker CS et al.; Chromatin isolated from immature oocytes was found to contain an endogenous RNA polymerase activity (RNA nucleotidyltransferase; nucleoside triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) that synthesizes predominately 5S RNA . However, the levels of total RNA synthesis and 5S RNA synthesis in chromatin were each stimulated 10- to 50-fold by an exogenous RNA polymerase III purified from X . laevis oocytes . The 5S genes in chromatin were transcribed by the exogenous enzyme in a highly selective (3000-fold above random) and predominately asymmetric fashion . A significant fraction of 5S RNA sequences were also found in a discrete transcript, approximately 5S in size . Total RNA synthesis was significantly stimulated when chromatin was transcribed by oocyte RNA polymerase I, murine RNA polymerase II, and low levels of Escherichia coli RNA polymerase . However, these enzymes did not significantly stimulate 5S RNA synthesis above the endogenous levels . Both homologous oocyte RNA polymerase I and III and E . coli RNA polymerase transcribed the 5S genes in deproteinized DNA to approximately the same extent (severalfold above random) and both the sense and anti-sense strands of the gene were transcribed . It appears, therefore, that both chromatin-associated components and a purified RNA polymerase III are necessary and sufficient for the selective and accurate transcription of the 5S RNA genes in vitro. Microbios, 1977, 18(71), 7 - 25 Oxygen toxicity: comparative sensitivities of membrane transport, bioenergetics and synthesis in Escherichia coli; Brown OR et al.; The oxygen sensitivities of basic cell functions were compared to evaluate their significance as potential causes of the reversible growth inhibition produced in Escherichia coli by exposure to hyperbaric oxygen . Growth and net incorporation of radioactive glucose into cell structure, and specifically in to protein, were completely inhibited in approximately 1/20 of a generation by a gas phase containing 4.2 atmospheres of oxygen . The inhibition occured before there was significant decrement in cellular glucose transport, respiration, or intracellular concentration of adenosine triphosphate . The data indicate that fundamental steps leading to protein biosynthesis from glucose should be examined in the search for specific primary sites of oxygen toxicity. Folia Microbiol (Praha), 1977, 22(3), 168 - 72 The activity of Escherichia coli DNA-dependent RNA polymerase on DNA templates of different origin . The effect of cAMP; Jiresova M et al.; DNA isolated from different T phages served as a better template for the synthetic activity of unmodified Escherichia coli RNA polymerase in the in vitro system than did the host DNA . cAMP significantly stimulated the activity of such a preparation of RNA polymerase . The stimulation was more pronounced with the host DNA template than with phage DNA . However, the synthetic activity of Escherichia coli RNA polymerase was greater in the presence of cAMP than without it when phage DNA served as the template. Acta Neurol Scand Suppl, 1977, 63, 145 - 56 In vitro lymphocyte transformation of MS patients to paramyxovirus antigens; Cunningham-Rundles S et al.; The immune response of 21 MS patients and 21 healthy volunteers was tested in vitro lymphocyte transformation assay . The stimulating antigens were measles, mumps, parainfluenza, E . coli, S . aureus and C . albicans . MS patients were found to respond similarly to the normal controls to all antigens tested with the exception of mumps antigen . The maximum responses of the MS patients to this antigen were significantly lower than those observed for the normals . However, since 95 per cent of the MS lower maximum responses were still within the positive range, the immunological significance of this phenomenon will require further clarification. Proc Natl Acad Sci U S A, 1977 Jan, 74(1), 49 - 53 Nucleotide sequence of the 5' end of araBAD operon messenger RNA in Escherichia coli B/r; Lee N et al.; The transcription reaction in vitro provides a means of analyzing the nucleotide sequence of the mRNA of the araBAD operon . By controlling the time of synthesis, we obtained araBAD mRNA of varying lengths beginning from the 5' end . These 5' fragments were freed of lambda RNA transcripts by successive hybridizations to the sense strands of a pair of lambda ara transducing phages that carry ara genes in opposite orientations . The purified 5' fragments were ordered by their times of appearance during synchronized RNA elongation and by nearest neighbor analyses . The results, when combined with the knowledge of the NH2-terminal sequence of the product of the first cistron (L-ribulokinase gene araB), establish the nucleotide sequence of the first 69 bases at the 5' end of the araBAD operon mRNA . The AUG starter codon for L-ribulokinase is located at positions 29-31 . The sequence is: 5' A-C-C-C-G-U-U-U-U-U-U-U-U-G-G-A-U-G-G-A-G-U-G-A-A-A-C-G-A-U-G-G-C-G-A-U-U-G-C-A-A-U-U-G-G-C-C-U-C-G-A-U-U-U-U-G-C-A-G-U-G-A-U-U-C-U-G-(U)- . . .3'. J Gen Virol, 1977 Jan, 34(1), 73 - 85 Protection of mice against encephalomyocarditis virus infection by preparations of transfer RNA; Stebbing N et al.; Preparations of bacterial transfer RNA (tRNA), give dose-dependent protection of mice against encephalomyocarditis (EMC) virus infection at up to I mg tRNA per mouse with maximum response when the tRNA is administered around 6 h before infection . Protection occurs with intraperitoneally and intravenously administered tRNA against infections by both these routes . In some experiments significant protection occurs by single treatments of tRNA up to 24 h after infection with virus doses of I X LD100 . Some tRNA preparations of eukaryotic origin do not give significant protection . Protection is not a feature of all species of bacterial tRNA; partially purified valine, tyrosine and phenylalanine tRNAs from Escherichia coli are not protective . tRNA treatment does not induce circulating interferon nor does it 'hypo-reactivate' the protective effect of poly (I).poly (C) treatment of mice . Humoral and cell mediated immune responses do not seem to be involved in tRNA mediated protection since first, cytosine arabinoside treatment does not affect protection by tRNA; second, serum from mice treated with tRNA and an EMC vaccine does not protect other mice against infection, and third, mice that survive normally lethal infections as a result of tRNA treatment are generally just as susceptible to re-infection as previously untreated, uninfected mice . Silica treatment abolishes protection of mice by tRNA implying that macrophages are necessary . However, tRNA does not seem to act by clearance of virus particles since vaccination of mice by inactivated EMC virus is not affected by tRNA treatment . These results are considered in relation to the presence of a tRNA-like structure in EMC virus RNA and protection of mice by other single stranded polynucleotides. J Gen Virol, 1977 Jan, 34(1), 177 - 82 Aminoacylation of encephalomyocarditis virus RNA; Lindley IG et al.; RNA extracted from purified encephalomyocarditis (EMC) virus (EMC-RNA) can be aminoacylated with synthetase praparations from Escherichia coli, beef and rabbit liver . The extent of aminoacylation is between 0-024 and 0-080 moles per mole EMC-RNA and occurs only with serine . Either removal of possible low mol . wt . contaminants with 3 M-sodium acetate nor periodate oxidation of the virus RNA affects its aminoacylation capacity. J Bacteriol, 1977 Jan, 129(1), 564 - 6 Role of the rel gene product in the control of cyclic adenosine 3',5'-monophosphate accumulation; Braedt G et al.; The presence of a relA mutant allele affects the kinetics of cyclic adenosine 3',5'-monophosphate accumulation during downshift from glucose to succinate . The nucleotide accumulates at the normal rate early in the downshift transition but continues to accumulate for a longer time in the relA mutant, leading to a two- to threefold excess by the end of the diauxic lag . Evidence is presented that this effect occurs independently of the accumulation of ppGpp. Folia Microbiol (Praha), 1977, 22(3), 198 - 205 Membrane mutation affecting energy-linked functions in Escherichia coli K 12; Brana H et al.; A small-colony forming variant of Escherichia coli with a mutation in the ncf gene was analysed . The alternation of the protein composition in the cytoplasmic membrane and the interaction with K and E group colicins indicated a membrane mutation . The effect of this mutation on some membrane-bound processes, the activity of Mg2+-activated ATPase, the growth on different carbon sources and the active transport of amino acids, is described . This mutation does not exert any effect on the electron transport system. Proc Natl Acad Sci U S A, 1977 Jan, 74(1), 193 - 7 A mechanism of duplex DNA replication revealed by enzymatic studies of phage phi X174: catalytic strand separation in advance of replication; Scott JF et al.; The enzyme system for duplicating the duplex, circular DNA of phage phi X174 (replicative form) in stage II of the replicative life cycle was shown to proceed in two steps: synthesis of the viral (+) strand }stage II(+)}, followed by synthesis of the complementary (-) strand }stage II(-)} {Eisenberg et al . (1976) Proc . Natl . Acad . Sci . USA 73, 3151-3155} . Novel features of the mechanism of the stage II(+) reaction have now been observed . The product, synthesized in extensive net quantities, is a covalently closed, circular, single-stranded DNA . The supercoiled replicative form I template and three of the four required proteins--the phage-induced cistron A protein (cis A), the host rep protein (rep), and the DNA polymerase III holoenzyme (holoenzyme)--act catalytically; the Escherichia coli DNA unwinding (or binding) protein binds the product stoichiometrically . In a reaction uncoupled from replication, cis A, rep, DNA binding protein, ATP, and Mg2+ separate the supercoiled replicative form I into its component single strands coated with DNA binding protein . In the presence of Mg2+, cis A, nicks the replicative form I; rep, ATP, and Mg2+ achieve strand separation with a concurrent cleavage of ATP and binding of DNA binding protein to the single strands . rep exhibits a single-stranded DNA-dependent ATPase activity . These observations suggest that the rep enzymatically melts the duplex at the replicating fork, using energy provided by ATP; this mechanism may apply to the replication of the E . coli chromosome as well. J Bacteriol, 1977 Jan, 129(1), 544 - 6 Pleiotropic phenotype of an Escherichia coli mutant lacking leucyl-, phenylalanyl-transfer ribonucleic acid-protein transferase; Deutch CE et al.; A mutant of Escherichia coli that lacks leucyl-, phenylalanyl-transfer ribonucleic acid-protein transferase had diminished activities of L-phenylalanyl-transfer ribonucleic acid synthetase and tryptophanase, grew faster than its parent with aspartic acid as the sole nitrogen source, accumulated higher levels of enterochelin in the medium during iron limitation, and exhibited an abnormal morphology. Mutat Res, 1977-78, 47(3-4), 141 - 60 A review of the genetic toxicology of chlorinated dibenzo-p-dioxins; Wassom JS et al.; Information from both published and unpublished sources considered relevant to the understanding of the genetic toxicology of chlorinated dibenzo-p-dioxins is summarized in this review . Interest in writing this paper was stimulated by the fact that this class of compounds, particularly 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), has gained notoriety as an extreme environmental and industrial hazard . The potential for human exposure occurs in the work place when dioxins are formed during the synthesis of a number of commercially important compounds such as 2,4,5-trichlorophenoxyacetic acid, hexachlorophene, and pentachlorophenol . Environmental contamination may result from manufacturing processes and from dioxin contaminants in marketed products . Research on dioxins as potential mutagens was initiated because of their structural similarity to acridines, a class of known intercalating agents . To date, only 4 dioxin compounds have been evaluated for mutagenicity: the di-, tetra-, and octa-chlorinated derivatives and the unsubstituted dibenzo-p-dioxin . Since only a few of the many possible structural forms of dioxins have been tested, no definite conclusions can be made about their potential mutagenicity . Furthermore, the positive mutagenicity and cytological effects reported thus far with the few dioxin isomers examined seems to depend on the position of chlorine substitution . The most active form of the molecule is the 2,3,7,8-derivative (TCDD) . Data available for assessing the mutagenic potential of TCDD are conflicting and scarce . Differences in testing results reported in these studies could be attributed to solubility problems with the test chemical, treatment protocols, purity of test samples, or toxicity . Because there are conflicting data, additional experiments are needed before the mutagenic potential of TCDD and other dioxins can be determined . Studies exploring the promoting effect of dioxins on the mutagenicity of other compounds are also recommended because experiments have shown TCDD to be an extremely active liver enzyme inducing agent that enhances the mutagenicity of certain polycyclic hydrocarbons such as 3-methylcholanthrene in vitro . The importance of discerning the hazards to human health from dioxin compounds became apparent after an accidental release of TCDD from a chemical plant contaminated the Seveso, Italy area in July 1976 . This accident revealed that insufficient data were available to properly evaluate the long-term health risks posed by dioxin compounds . Several research projects were therefore initiated after the Seveso incident; it is hoped that many of the questions concerning the mutagenicity of TCDD and possibly of other dioxin congeners will be answered as a result of this work. Acta Univ Carol Med Monogr, 1977, (77 Pt 1), 113 - 7 Intestinal gradient of enterokinase activity in different species of animals; Malis F et al.; The proximodistal gradient of enterokinase activity was studied in mucosal homogenates of the duodenum, jejunum, ileum, caecum (or megacaecum) and sigmoid flexure of various mammals . The study was carried out in groups of 5 monkeys, guinea pigs, dogs and rats and also in gnotobiological rats--conventional (n = 5), germ-free (n = 10) and monocontaminated (n = 5) with Escherichia coli 0 86 . Enterokinase activity was likewise determined in duodenal mucosal homogenates prepared from material resected at operation from adult humans (n = 5) and from a group of monkeys (n = 5), with and without the addition of Triton X-100 . Enzymatic activity was determined by a modification of Nordstrom and Dahlqvist's method, using pH-stat titration . In all the animals, enterokinase values were unequivocally the highest in the duodenal mucosa; in the other intestinal segments it displayed a marked aboral decrease, so that we found about 30% of duodenal activity in the jejunum, trace amounts in the ileum and zero values in the caecum and the sigmoid flexure . In the individual animals, the enterokinase activity values fell in the sequence monkey greater than guinea-pig greater than dog greater than rat . Enterokinase activity in the human duodenum was practically the same as in the rat duodenal mucosa . No reciprocal differences were found in gnotobiological rats . Either whole homogenate or the supernatant of triton-treated homogenate can be used for the demonstration of enterokinase in laboratory practice . The only part which can be employed for diagnostic purposes in duodenal mucosa. Acta Microbiol Pol, 1977, 26(2), 129 - 35 Dependence of efficiency of DNA transfer and recombinat formation on cell cycle of Hfr in Escherichia coli K-12; Mycielski R et al.; The efficiency of DNA transfer during the Hfr cell cycle, studied with the use of 3H-thymidine, is the highest in the first half of the cycle . The efficiency of recombinant formation in the Hfr cell cycle demonstrates a similar periodicity only when the ratio of 1 Hfr cell to 8 or more F- cells in mating mixture is maintained . The absence of such changes in the number of recombinants during the cell cycle of a donor with relative excess of Hfr cells seems to be caused by limitation of the number of recombinants by the competent recipent cell fraction. Acta Microbiol Pol, 1977, 26(2), 119 - 28 Kinetics of pair formation during cell cycle of Hfr and F in Escherichia coli K-12; Mycielski R et al.; Pair formation ability in mating mixture of synchronized Hfr or F- culture and asynchronous culture of appropriate partner was studied . The obtained results allow to conclude that the pair formation ability of F- cells is stable over the whole cell cycle whereas in Hfr cells is it subject to cyclic changes with maximum in the first half of the cycle. Acta Microbiol Pol, 1977, 26(1), 19 - 26 On the combined action of drugs on the lambda prophage induction in Escherichia coli K12 cells; Gajcy H et al.; The capability of methotrexate, jododeoxyuridine and 5-fluorouracil to induce lambda prophage was compared when given alone or in combination . All these drugs were found to cause inducing conditions in Escherichia coli K12(lambda) cells . Combined action of jododeoxyuridine and methotrexate resulted in a pronounced increase in the number of free phages compared with that resulting the treatment either with methotrexate of jododeoxyuridine alone . Treatment with 5-fluorouracil caused inactivation of plaque forming ability in cells induced with methotrexate. Microbios, 1977, 19(77-78), 205 - 12 Transport capacity, alkaline phosphatase activity and protein content of glutaraldehyde-treated cell forms of Escherichia coli; Gorman SP et al.; Studies on the comparative transport capacity of various cell forms of Escherichia coli suggest that glutaraldehyde acts only in the outer regions of the cell envelope and to such an extent that transport of alpha-aminoisobutyric acid is reduced by 50% . Alkaline phosphatase activity in whole cells was severely impaired in the presence of alkaline glutaraldehyde and in NaCl-washed cells both acid and alkaline glutaraldehyde (0.01%) caused approximately 80-90% reduction in enzyme activity in 10 min . Protein content was reduced by only 10-15% with this concentration of glutaraldehyde, and cell volume decreased by the same extent . These results are discussed in terms of the mode of action of the disinfectant. J Neurosci Res, 1977, 3(1), 63 - 72 Endotoxin alters spontaneous transmitter release at the frog neuromuscular junction; Person RJ; The direct neurotoxic effects of E . coli endotoxin (ETX) on spontaneous transmitter release were tested at the frog sartorius muscle neuromuscular junction . Spontaneous transmitter release was monitored by intracellularly recording miniature end-plate potentials (MEPPs) . Junctions were continuously exposed to standard concentrations of 10 microgram/ml of 3 ETX samples, 2 of which produced a significant elevation of MEPP frequency followed by a decline of frequency to very low rates . The third ETX sample, known to have a decreased canine lethality, was without effect on MEPP frequency . No significant changes in MEPP amplitude were evident . The rate of change in MEPP frequency, but not the peak frequency, was reduced by lowering ETX concentrations . Alterations in MEPP frequency induced by ETX were prevented by removing Ca++ and antagonized by high {K+}out . The results suggest that ETX alters ion conductance channels, particularly those for Ca++, in the presynaptic terminal membrane. Circ Shock, 1977, 4(4), 369 - 77 Endotoxemia and large intestinal blood flow in subhuman primates; Swan KG et al.; The hemodynamic effects of Escherichia coli endotoxin (LD80) were measured in the large intestine of anesthetized Rhesus monkeys to determine whether this organ contributes to the pathogenesis of experimental shock . Inferior mesenteric arterial blood flow (IMF) was measured with an electromagnetic flowmeter . Pressures within the aorta (AP) and portal vein (PP) were recorded . Distribution of colon blood flow was measured with radioactive microspheres: Ce, Sr, and Cr were injected into the left heart . Reference blood samples were obtained from a femoral artery . Mean control IMF was 22.9 +/- 2.2 (SE) ml/min . Aortic pressure was 113 +/- 11 mm Hg, and PP was 6 +/- 1 mm Hg . Arterial blood pH was 7.43 +/- 0.02; pO2 and pCO2 were 93.4 and 37.1 mm Hg, respectively . All parameters were measured at hourly intervals for 4 hr . Neither IMF nor its distribution within the colon changed during the entire observation period . Aortic pressure fell to a low of 60 +/- 6 mm Hg (p less than 0.02) at 3 hr; PP, pO2 and pCO2 were unchanged by endotoxin . Arterial blood pH fell to 7.315 +/- 0.020 at 4 hr (p less than 0.01) . These observations indicate that the colon is not a "target organ" of endotoxic shock in subhuman primates, despite considerable hypotension and metabolic disturbances subsequent to near lethal endotoxemia. C R Seances Soc Biol Fil, 1977, 171(3), 516 - 25 {Guanyl cyclase activity in the EF-T elongation factor of Escherichia coli}; Macchia V et al.; Highly purified EF-Ts from E . coli does contain guanylate cyclase activity, which is absent from other purified transfer factors, such as EF-Tu and EF-G . Guanylate cyclase activity has been characterized by its sensitivity to inhibitors and substrate specificity . Although the physicochemical properties of guanylate cyclase are closely related to those of EF-Ts, it does not appear to be a contaminant of this transfer factor, but a specific enzyme . The possible role of guanylate cyclase in protein synthesis is discussed. Nucleic Acids Res, 1977, 4(5), 1513 - 37 Shear degradation of DNA; Adam RE et al.; A concentric-cylinder flow-birefringence instrument is used to generate sufficient shear fields to break T2 DNA (M = 1.2 X 10(8)) and E . coli DNA (M = 2.5 X 10(9)) in dilute solution . Breakage is monitored in situ by measuring the change in birefringence relaxation after the flow has been stopped . The breakage of T2 DNA follows first-order kinetics . Rate constants are obtained as functions of shear rate and viscosity (varied by adding glycerol) . The data are fitted by a modified Arrhenius equation, assuming that stess increases the rate by lowering the activation energy . The rate increases with temperature, pH, and water concentration, and appears to be a base-catalyzed hydrolysis of the phosphate-ester linkage . La3+ ions catalyze the reaction . E . coli DNA was reduced to half molecules at a shear stress of 0.4 dynes/cm2, which is about 2500 times less than that required for T2 . The difference in rates is accounted for in part by the difference in size of the two, but may also reflect the presence of many single-strand nicks in the coli DNA. J Pak Med Assoc, 1977 Jan, 27(1), 262 - 4 L-asparaginase--antileukemia agent; Bukhari SZ et al.; This paper describes the most recent development in the field of biosynthesis of L-Asparaginase by means of various culture, purification by Column Chromatography, informations of the Catabolite repression of L-Asparaginase and its metabolism in mycobacteria . The separation, purification studies, idea about the effect of different PH on activity, quaternary structure and the effect of specific antibodies on catalytic activity of L-Asparaginase is discussed . This material shows the role of L-Asparaginase in acute lymphocytic leukemia. Z Allg Mikrobiol, 1977, 17(3), 221 - 5 {Bistability in the activity of glutamine synthetase in ammonium-limiting chemostat cultures of Escherichia coli ML 30}; Muller PJ et al.; The approximative estimation of the function micron({NH+4}) in cultures of E . coli ML 30 had shown that bistability of the ammonium concentration in ammonium limited continuous cultures could be possible (BERGTER et al . 1977) . This phenomenon suggested a bistability in the regulation of ammonia assimilation . Therefore, the activity of one key enzyme of the two ammonia assimilation systems was measured . The distribution of the activity of glutamine synthetase in ammonia limited continuous cultures after different transition states confirmed this suggestion. Acta Biochim Pol, 1977, 24(1), 53 - 8 Purification and properties of L-asparaginase EC-2 from Escherichia coli 055:B5; Pajdak E et al.; 1 . L-Asparaginase has been isolated from aerobically grown Escherichia coli 055:B5 and purified about 140-fold in a three-step procedure involving acidification to pH 4.5, ammonium sulphate fractionation and column chromatography on DEAE-Sephadex A-50 . The activity of the preparation is 140 U/mg protein . 2 . The enzyme acts within a broad pH range (pH 5-9) and is affected neither by PCMB, N-ethylmaleimide nor metal ions . 3 . Molecular weight of the isolated asparaginase is 130 000. Nucleic Acids Res, 1977 Jan, 4(1), 85 - 98 Equimolar addition of oligoribonucleotides with T4 RNA ligase; Uhlenbeck OC et al.; T4 induced RNA ligase will join equimolar concentrations of two oligoribonucleotides, (Ap)3C and p(Up) 5, to form a single product, (Ap)3Cp(Up) 5, in high yield . The presence of the 3' phosphate on p(Up)5 prevents the oligomer from adding to itself . The pH optimum of the reaction is about 7.5, but less of the undesirable adenylated intermediate, App(Up) 5, forms at pH 8.2 . The reaction rate is a linear function of oligomer concentration from 3 micronM to 0.6 mM . The data suggest that T4 RNA ligase will be a useful enzyme for the synthesis of oligomers of defined sequence. Bioinorg Chem, 1977, 7(1), 1 - 4 Selective reactions of nucleobases under biological conditions; Beck MT et al.; Pentacyanonitrosylferrate/II/ complex reacts under biological conditions (pH= 7.5, T= 25-40 degrees C, dilute solution) selectively with nucleobases . The reaction with adenine and guanine probably leads to nitrosation . A new compound formed in the reaction with adenine is prepared; both this compound and the pentacyanonitrosylferrate/II/ inhibits the multiplication of Escherichia coli. J Bacteriol, 1977 Jan, 129(1), 108 - 14 Partial purification and some properties of delta1-pyrroline-5-carboxylate reductase from Escherichia coli; Rossi JJ et al.; delta1-Pyrroline-5-carboxylate (PCA) reductase {L-proline:NAD(P)+5-oxidoreductase, EC 1.5.1.2} has been purified over 200-fold from Escherichia coli K-12 . It has a molecular weight of approximately 320,000 . PCA reductase mediates the pyridine nucleotide-linked reduction of PCA to proline but not the reverse reaction (even at high substrate concentrations) . The partially purified preparation is free of competing pyridine nucleotide oxidase, PCA dehydrogenase, and proline oxidase activities . The Michaelis constant (Km) values for the substrate, PCA, with reduced nicotinamide adenine dinucleotide phosphate (NADPH) or NADH as cofactor are 0.15 and 0.14 mM, respectively . The Km values determined for NADPH and NADH are 0.03 and 0.23 mM, respectively . Although either NADPH or NADH can function as cofactor, the activity observed with NADPH is severalfold greater . PCA reductase is not repressed by growth in the presence of proline, but it is inhibited by the reaction end products, proline and NADP. Mol Gen Genet, 1976 Dec 31, 142(4), 263 - 75 Reversion of the gal3 mutation of Escherichia coli: partial deletion of the insertion sequence; Ahmed A et al.; The gal3 mutation of E . coli is an insertion of a DNA sequence, 1,100 base pairs in length, into the operator-promoter region of the galactose operon . This mutation reverts spontaneously to gal+ by excision of the insertion to produce stable, inducible revertants, or by tandem duplications of the gal operon to produce unstable, constitutive revertants . The nature of a third class of revertants, which are stable and constitutive, is the subject of the present study . The stable, constitutive class of revertants included approximately 30% of all gal+ revertants obtained from a gal3 (lambda) strain . Although the constitutive reversions could be transduced by lambda, the efficiency was found to be extremely poor and the rare transductants which did appear seemed to originate from abnormal transducing particles . It was concluded that these reversions were not normally packaged by lambda . In order to facilitate the packaging of these reversions, the chlD-pgl region was deleted from the parent gal3 (lambda) strain . Unexpectedly, the gal3 mutation in the majority of these deletions reverted to produce stable, constitutive reversions exclusively . The explanation proposed was that the chlL-pgl deletions had also removed part of the gal operator-promoter . These revertants were not considered to be true representatives of the stable, constitutive class . The specificity of deletion end-points at the insertion was found only in the gal3 (lambda) strain, and not in gal+, gal+(lambda), or gal3 strains . Moreover, the frequency of spontaneous chlD-pgl deletions increased 10- to 15-fold in presence of the gal3 insertions . A lambdagal phage bearing a true stable, constitutive reversion (galc200) was isolated from the revertant strain by subsequent deletion of the chlD-pgl segment (delta31) . Electron micrographs of lambdagal+ and lambdac200 delta31(chlD pgl) DNA heteroduplexes were interpreted to indicate that the stable, constitutive reversion had arisen by a deletion of 3/4 of the gal3 insertion sequence . The main conclusions are: (i) the stable, constitutive reversions of gal3 can arise by partial deletions of the insertion sequence, apparently by elimination of the nucleotide sequence which causes polarity; (ii) the chlD-pgl deletions may exhibit preferential termination at the right extremity of the gal3 insertion in presence of prophage lambda; and (iii) the gal3 insertion appears to inhibit the production of lambdagal particles by providing a nucleotide sequence which is recognized and degraded by a specific endonuclease . It is suggested that inhibition of transducing particle formation by gal3 and the preferred termination of deletions at gal3 might represent related phenomena. Thromb Haemost, 1976 Dec 31, 36(3), 495 - 502 Severe antithrombin III deficiency in an infant associated with multiple arterial and venous thromboses; Mendelsohn G et al.; Inherited antithrombin III (AT-III, heparin cofactor) deficiency is a rare condition, presenting with thrombotic disease in adult life . This paper reports an 8 months old South African Black male infant with multiple large vessel venous and arterial thromboses, and E . coli septicaemia . This was associated with an extremely low plasma AT-III level . Micronodular cirrhosis and intracytoplasmic hyaline globules in the liver cells were present . These globules were eosinophilic, and PAS-positive after diastase . They measured approximately 5 mu to 30 muin diameter, occurred singly in the liver cells and were located mainly in the periportal areas . The histological findings in the liver are similar to those observed in alpha 1-antitrypsin (AAT) deficiency in which the intracytoplasmic globules represent accumulation of altered AAT . Immunochemical studies carried out on formalin fixed tissue failed to detect cross reaction material with anti-alpha 1 antitrypsin or anti-AT III antiserum . This is the first case report of AT-III deficiency presenting in infancy . It is also the first case associated with distinctive liver pathology . The available data presented are insufficient to distinguish between an inborn defect and acquired caused of the severely depressed AT-III plasma level and the distinctive liver pathology. J Mol Evol, 1976 Dec 30, 8(4), 317 - 28 Selective disadvantage of non-functional protein synthesis in Escherichia coli; Andrews KJ et al.; Comparison of growth rates of isogenic strains that synthesize varying levels of beta-galactosidase during continuous culture on non-inducing medium indicates that synthesis of low levels of non-functional protein has a small but possibly significant effect upon growth rate. Biochemistry, 1976 Dec 28, 15(26), 5769 - 75 Location of accessible bases in Escherichia coli formylmethionine transfer RNA as determined by chemical modification; Schulman LH et al.; Chemical modification of Escherichia coli tRNAfMet with 1 M chloroacetaldehyde, pH 5.5-6.0 at 25 degrees C, has been found to result in alteration of six cytidine and five adenosine residues in the molecule . The modified cytidine residues are the same as those previously found to be reactive with sodium bisulfite at pH 6.0 . The accessible adenosine residues are A36 in the anticodon, A58 in the T psi C loop, and A73, A74, and A77 in the 3; terminal sequence . No modification of adenosine residues in the dihydrouridine or variable loops or of adenosine residues on the 3' side of the anticodon loop could be detected . Treatment of fMet-tRNAfMet with chloracetaldehyde gave the same pattern of midofication as was observed with deacylated tRNAfMet . Chemical modification of E . coli tRNAfMet with 2 sodium bisulfite, pH 7.0 at 25 degrees C, resulted in selective modification of exposed uridine residues in the tRNA . Only three sites were found to be reactive: U18 in the dihydrouridine loop, U37 in the anticodon, and U48 in the variable loop . The overall pattern of chemical modification of tRNAfMet is very similar to that found by others for yeast tRNAPhe, supporting the idea that many of the tertiary interactions in the two tRNAs are the same . The adenosine residue at position 58 in the center of the T psi C loop of the initiator tRNA shows unusual reactivity, however, being modified by chloroacetaldehyde at the same rate as the 3' terminal adenosine residue . This result is in sharp contrast to the uniform resistance of nucleotides in the T psi C loop of yeast tRNAPhe to chemical modification. Biochemistry, 1976 Dec 28, 15(26), 5776 - 83 Physicochomecial studies on interactions between DNA and RNA polymerase . Isolation and mapping of a T7 DNA fragment containing the early promoters for Escherichia coli RNA polymerase; Hsieh T et al.; The cleavage sites in the early promoter region of coliphage T7 have been mapped for four restriction enzymes . They are, from the left end in base pairs, 1100 and 740 for Hinf; 680, 320, 530, 240, 77, and 67 for Hind II; 620 and 530 for Hpa II; 790 for Alu I . The nucleotide sequence between the Hind II site at 680 base pairs from the left end and the Hinf site at 740 base pairs from the left end has been determined, from which the start point of the promoter A3 is located at 720 base pairs from the left end . The start points of the other two major promoters A1 and A2 are deduced to be at 460 and 580 base pairs from the left end, respectively, from the chain lengths of the in vitro transcripts off the 1100 base-pairs long Hinf fragment . Similar to the sequences of a pL and pR promotors of phage lambda and a sequence in Simian Virus 40 used by Escherichia coli RNA polymerase as a promotor, the sequence of the A3 promotor of T7 also has a Hind II restriction site approximately 30 base pairs upstream to the start point of RNA synthesis . No such Hind II sites exist, however, for the A1 and A2 promoters . Experiments on the protection of some of the restriction sites on the 1100 base-pairs-long Hinf fragment by RNA polymerase binding support the electron microscopic observations of others that, in addition to the three sites A1, A2 and A3, there is at least a fourth site at which E . coli RNA polymerase can bind strongly . In addition to the Hind II site at 680 base pairs from the left end and the Hinf site at 740 base pairs from the left end, which are presumably protected by the binding of a single RNA polymerase at the A3 site, the Hind II site at 240 base pairs from the left end is also protected at a level of 5 polymerase molecules/DNA fragment . The possible existence of several minor promotor sites in the early promotor region, in addition to the three major promotor sites, is discussed. Biochemistry, 1976 Dec 28, 15(26), 5743 - 53 Kinetics of ribosome dissociation and subunit association studied in a light-scattering stopped-flow apparatus; Gorisch H et al.; The association-dissociation kinetics of ribosomes from Escherichia coli have been studied under various conditions in a light-scattering stopped-flow apparatus . The dissociation reaction at 2 mg/ml at 25 degrees C, induced by lowering the MgCl2 concentration from 18 to 3 mM, can best be described by three independent first-order processes with rate constants of 15 s-1, 0.9 s-u, and 3 X 10(-2) s-1, the slowest process comprising about 60% of the overall reaction . The fraction of ribosomes dissociating with the fastest rate (15 s-1) is concentration dependent and becomes negligible at 0.1 mg/ml9 Ribosomes treated with puromycin also show three dissociation rates with essentially the same rate constants as the nontreated samples . The dissociation induced by a high KCl concentration (0.85 MKCl, 18 mM MgCl) also shows three first-order phases with the same rate constants as for the dissociation induced by lowering the MgCl2 concentration . The formation of 70S ribosomes from 30S and 50S subunits, induced by increasing the MgCl2 concentration from 2 to 21 mM, follows second-order biphasic kinetics . A detailed analysis of the kinetic results shows that the two principal ribosomal forms must have one type of subunit in common . When the association data are analyzed assuming that the kinetic heterogeneity arises from two forms of only one subunit, the rate constants are found to be 6.4 X 10(6) and 1.05 X 10(6) M-1 s-1 . Sequential flow experiments show that the rapid and slow association species are to be identified, respectively, with phases II (0.9 s-1) and III 0.03 s-1) of dissociation . Relaxation measurements show that these correspond to type B ("loose") and A ("tight") ribosomes, respectively . Tight and loose ribosomes were isolated by sucrose density centrifugation, and dissociation and association kinetic studies confirmed the above assignments . Furthermore, the rate constants for these ribosoems agreed within experimental error with rate constants derived from analysis of the multiphasic kinetic data . The association rate constants are for ribosomes dissociated by dilution with the appropriate buffer immediately before recording the kinetics of association . Ribosomes dissociated by dialysis overnight against 2 mM MgCl2 show an association rate constant for the slower association reaction (type-A ribosome) that is about four times smaller, whereas the rate constant for the faster process is roughly the same . The activation energies of the dissociation reactions, whether induced by lowering the MgCl2 concentration or increasing the KCl concentration, and the association raaction induced by increasing the MgCl2 concentration are less than 3.5 kcal/mol . The rate constants of the dissociation at 3 mM MgCl2 and of the association reaction at 21 mM MgCl2 do not vary between pH 7.2 and 8.4 . When 30S and 50S subunits are flowed against buffer containing 20 mM spermidine, the association process is monophasic, with an association constant k - 6 X 10(6) M-1 s-1... J Biol Chem, 1976 Dec 25, 251(24), 779 - 84 Cross-linking of initiation factor IF2 to proteins L7/L12 in 70 S ribosomes of Escherichia coli; Heimark RL et al.; Initiation factor IF2 bound to the 70 S initiation complex with 5'-guanylyl methylenediphosphonate was treated with the cross-linking reagent, dimethyl-3,3'-dithiobispropionimidate . Covalent cross-linking of the factor to ribosomes was demonstrated by stabilization of initiation factor IF2-70S complexes during centrifugation at high salt concentrations . Specific cross-linking of the factor to the 50 S proteins L7/L12 was shown by: (a) co-precipitation of the 50 S proteins L7/L12 by antibodies made against initiation factor IF2 and (b) the appearance of radioactive bands containing {32P}phosphoryl initiation factor IF2 in regions of elevated molecular weight following polyacrylamide/dodecyl sulfate gel electrophoresis . One major band had an apparent molecular weight of 132,000, consistent with its being a dimer containing one copy of L7/L12 (13,000) and initiation factor IF2 (120,000) . This cross-linked species was shown to contain {32P}phosphoryl initiation factor IF2 and 35S-labeled L7/L12 in separate experiments . It is concluded that L7/L12, which were shown previously to be required for the binding of the factor, are located at or near the initiation factor IF2 binding site on the 70 S initiation complex. Mol Gen Genet, 1976 Dec 22, 149(3), 329 - 33 Transfer gene expression during fertility inhibition of the Escherichia coli K12 sex factor F by the I-like plasmid R62; Gasson M et al.; Further understanding of how the FinQ fertility inhibition system of the I-like plasmid R62 inhibits transfer of the sex factor F has been gained by the use of a genetic assay for individual transfer gene products . The technique involved construction of a series of Flac plasmids carrying suppressible mutations in individual transfer genes together with a FinQ inhibitor-insensitive traQ mutation . The transfer of the Flac double mutants from a strain carrying wild-type Fhis and R62 then indicated the effect of R62-encoded transfer inhibition on the expression of individual F transfer genes . During such inhibition the products of genes traJ, traA, traE, traB and traC were present in quantities sufficient to permit efficient F transfer, whereas the levels of the traF, traH, traG and traD gene products were so reduced as to limit F transfer . These findings and a failure to obtain recombination between traC and traQ mutations suggest that the R62 fertility inhibition system terminates transcription of the transfer operon between traC and traF. Mol Gen Genet, 1976 Dec 22, 149(3), 323 - 8 Transfection of Escherichia coli by Mu DNA; Kahmann R et al.; Infectivity of Mu DNA was demonstrated in Ca+ +-treated Escherichia coli cells that lacked the nucleases Exo V and Endo I . The efficiency of transfection is about 10(-7) per phage equivalent . Infectivity is destroyed by denaturation of Mu DNA, and cannot be restored by renaturation. Mol Gen Genet, 1976 Dec 22, 149(3), 297 - 302 Isolation and characterization of temperature-sensitive mutants of Escherichia coli with altered ribosomal proteins; Isono K et al.; The ribosomal proteins of temperature-sensitive mutants of Escherichia coli isolated independently after mutagenesis with nitrosoguanidine were analyzed by two-dimensional gel electrophoresis . Out of 400 mutants analyzed, 60 mutants (15%) showed alterations in a total of 22 different ribosomal proteins . The proteins altered in these mutants are S2, S4, S6, S7, S8, S10, S15, S16, S18, L1, L3, L6, L10, L11, L14, L15, L17, L18, L19, L22, L23 and L24 . A large number of them (25 mutants) have mutations in protein S4 of the small subunit, while four mutants showed alterations in protein L6 of the large subunit . The importance of these mutants for structural and functional analyses of ribosomes is discussed. Mol Gen Genet, 1976 Dec 22, 149(3), 291 - 6 The effects of the relA gene on the synthesis of aminoacyl-tRNA synthetases and other transcription and translation proteins in Escherichia coli A; Blumenthal RM et al.; The effects of a partial restriction of valyl-tRNA aminoacylation on the synthesis of aminoacyl-tRNA synthetases, ribosomal proteins, and other translation and transcription proteins were examined in otherwise isogenic stringent (relA+) and relaxed (relA1) derivatives of E . coli B . The synthesis of individual ribosomal proteins, elongation factor G, and to a lesser extent elongation factors Tu and Ts, and the valyl- and arginyl-tRNA synthetases was found to be subject to the influence of the stringent control system . The synthesis of the alpha and beta subunits of RNA polymerase and several of the aminoacyl-tRNA synthetases, in contrast, is either not subject to the influence of the stringent control system, or is subject to additional regulatory constraints. Mol Gen Genet, 1976 Dec 22, 149(3), 279 - 89 Biosynthetic regulation of individual proteins in relA+ and relA strains of Escherichia coli during amino acid starvation; Reeh S et al.; An isogenic pair of Escherichia coli mutants (relA+ tufB valSts and relA1 tufB valSts) has been cultured at several temperatures to establish various degrees of limitation for valyl-tRNA synthetase . The biosynthetic rate of 16 identifiable proteins, most of which are components of the transcription and translation apparatus, was measured by pulse-labelling with {35S}-methionine, followed by protein separation using two-dimensional gel electrophoresis (O'Farrell, 1975) . No single pattern of response to amino acid starvation of biosynthetic rate was observed . EF-Ts, L12 and S6 were found to be under strong stringent and relaxed regulation; EF-G, EF-Tu-A and S1 are under strong stringent, but weak relaxed regulation; EF-Tu-B, alpha, VRS, IRS and ARS are under week stringent and weak relaxed regulation; beta is under weak stringent regulation and does not respond at all to relaxed conditions; the biosynthetic rate of a protein called stringent starvation protein is strongly stimulated, relative to other proteins, in the starved stringent strain. Mol Gen Genet, 1976 Dec 22, 149(3), 273 - 7 Hyper-recombination in dam mutants of Escherichia coli K-12; Marinus MG et al.; F-prime heterogenotes of dam-3 bacteria segregate F-prime homogenotes at a frequency 30-200 times higher than the isogenic dam+ strain . A hyperrecombination mutant which shows increased recombination between chromosomal duplications was characterized as a dam mutant . The dam-3 allele causes a reduction in linkage of proximal unselected markers in transconjugants and increases the recombination frequency between a pair of closely linked markers . It is concluded that dam mutations confer a hyperrecombination phenotype to the cell. Mol Gen Genet, 1976 Dec 22, 149(3), 255 - 65 A transcriptional barrier in the regulatory region of the tryptophan operon of Escherichia coli: its role in the regulation of repressor-independent RNA synthesis; Pouwels PH et al.; A study was made of the influence of the growth rate of Escherichia coli bacteria on the transcription of the tryptophan (trp) operon, in various trp repressor negative strains . Selective measurement of the levels of RNA transcribed from the regulatory region (reg) of this operon and from the structural genes, respectively, has revealed that the increase of the rate of trpRNA synthesis with bacterial growth rate (Rose and Yanofsky, 1972) is due to a decrease of the frequency of termination of transcription at the transcriptional barrier in the regulatory region of the operon . In a mutant strain of E . coli with a deletion covering the promotor distal part of the regulatory region of the trp operon where the barrier is located, the rate of trpRNA synthesis is not affected by the growth rate . In suA- strains, in which Rho factor activity is reduced the bacterial growth rate does not affect the rate of synthesis of trpRNA . This result suggests that in wild type bacteria Rho factor contributes to the control of the transcription of the trp operon . In bacteria with a mutation rendering Tryptophanyl-tRNA synthetase (TRSase) inactive (trpS- strains) the rate of trpRNA synthesis is affected by the growth rate in the same way as in the isogenic wild type bacteria . This result indicates that TRSase plays no obligatory role in the control of trpRNA synthesis through a mechanism of termination and anti-termination of transcription, at least not in the studied strains, which carried a relA mutation. Mol Gen Genet, 1976 Dec 22, 149(3), 243 - 9 A virus-specified mechanism for the prevention of multiple infection--T7- and T3-mutual and superinfection exclusion; Hirsch-Kauffmann M et al.; Co- and superinfection of cells with T3/T7 result in exclusion (mutual or superinfection exclusion) . The exclusion mechanism is also directed against homologous (or identical) virus . Exclusion is established after the adsorption but before the genome becomes available for gene expression or replication, that is only one virus per cell develops . The exclusion is triggered by a constituant of the viral particle . An early T7 gene (M gene) (Schweiger et al., 1975) is essential for the formation of exclusion competent virions. Biochim Biophys Acta, 1976 Dec 22, 453(2), 418 - 25 UDP-glucose dehydrogenase from Escherichia coli . Purification and subunit structure; Schiller JG et al.; UDPglucose dehydrogenase from Escherichia coli has been purified 330-fold with an overall yield of 27% . A single homogeneous subunit was demonstrated by ultracentrifugation in 6 M guanidium chloride and by dodecyl sulfate-polyacrylamide gel electrophoresis . Since the molecular weight of the intact dehydrogenase is in the order of 86 000 and the subunit weight determined by the dodecyl sulfate-polyacrylamide gel electrophoresis is 47 000, the enzyme consists of two polypeptide chains . The sole amino terminal acid shown by the dansylation technique was arginine . Forty-four tryptic peptides were obtained by peptide mapping, in agreement with the number of arginine and lysine residues/mole protein {43} determined by amino acid analysis . The data are consistent with the presence of two identical or very similar polypeptide chains in E . coli UDPglucose dehydrogenase. Biochim Biophys Acta, 1976 Dec 22, 453(2), 383 - 90 A study of the enzymic dephosphorylation of beta-casein and a derived phosphopeptide; West DW et al.; beta-Casein, and the phosphate containing peptide derived from it by tryptic digestion, have been dephosphorylated by the action of two phosphatases . Escherichia coli alkaline phosphatase (EC 3.1.3.1) has been shown to remove the phosphates from these substrates in two distinct stages . Substrate molecules retaining three of the original phosphoseryl residues accumulate during the reaction and are resistant to further dephosphorylation at low enzyme concentrations . In contrast bovine spleen phosphoprotein phosphatase (EC 3.1.3.16) achieves complete dephosphorylation of these substrates sequentially without any of the intervening species showing resistance to the action of the enzyme . The phosphopeptide has been partially dephosphorylated by the action of the two phosphatases and the resultant peptides containing three phosphoseryl residues compared in their reactivity toward the E . coli alkaline phosphatase . The results obtained are discussed in relation to the mode of action of the two enzymes. C R Acad Sci Hebd Seances Acad Sci D, 1976 Dec 20, 283(16), 1815 - 8 {Antiglycogen activity of rabbit antisera raised against a strain of Escherichia coli 013}; Zweibaum A et al.; Rabbit antisera raised against a strain of E . coli 013 (Su 4321/41 013 K11 H11) contain high titres of antiglycogen antibodies . This activity was evidenced through positive immunofluorescent reactions observed on liver and muscle sections . Such reactions disappeared when the sections were previously treated with alpha-amylase . They were inhibited with Oyster glycogen, phenolalcohol, perchloric acid, and trichloroacetic liver extracts . These same substances had no inhibiting activity when treated with alpha-amylase . The immunofluorescent reactions were negative on livers from Mice treated with endotoxins and insulin which are known to deplete the stores of liver glycogen . The antisera gave interfacial precipitates with glycogen and liver extracts . The same substances, as well as the LPS from E . coli 013, had a specific inhibiting activity in a radioimmunoassay test using glycogen linked to bovine serumalbumine labeled with 125I. Chromosoma, 1976 Dec 16, 59(2), 89 - 101 Electron microscopy of membrane-free folded chromosomes from Escherichia coli; Kavenoff R et al.; Membrane-free folded chromosomes were purified from log-phase cultures of Escherichia coli and prepared for electron microscopy by aqueous (Kleinschmidt and Zahn) spreading . The appearance of the chromosomes depended on the salt concentrations in spreading . At certain salt concentration, the chromosomes resembled rosettes, with supercoiled loops of DNA radiating from a central core containing RNA . The rosettes support previous models deduced from physical studies of folded chromosomes . Apparently, cores contain must of the visible RNA, and the organization of the core is linked to the organization of the DNA loops. Biochem J, 1976 Dec 15, 160(3), 813 - 6 Effects of dicyclohexylcarbodi-imide on proton translocation coupled to fumarate reduction in anaerobically grown cells of Escherichia coli K-12; Gutowski SJ et al.; The addition of dicyclohexylcarbodi-imide to anaerobic cells of Escherichia coli K12 decreases both the observed extent of proton translocation coupled to fumarate reduction by endogenous substrates and the t 1/2 of proton re-entry after such translocation, but does not affect fumarate uptake . Dicyclohexylcarbodi-imide also inhibits fumarate reductase activity in cell extracts. Biochem J, 1976 Dec 15, 160(3), 721 - 6 Peptidyltransferase activity of ribosomes and a ribosome precursor from a mutant of Escherichia coli; Sims PF et al.; Escherichia coli strain 15-28 is a mutant with a defect in ribosome synthesis that caused the accumulation of ribonucleoprotein ('47S') particles during exponential growth . These particles are precursors to 50S ribosomes that lack three ribosomal proteins . Peptidyltransferase activity and binding at the peptidyl site of the peptidyltransferase centre are greatly decreased in 47S particles . Both these activities are lower in the 50S and 70S ribosomes of strain 15-28 than in its parent . Unusual assembly of the larger ribosomal subunit in strain 15-28 may produce completed ribosomes with diminished biological activity. Biochem J, 1976 Dec 15, 160(3), 505 - 19 A study of the influence of magnesium ions on the conformation of ribosomal ribonucleic acid and on the stability of the larger subribosomal particle of rabbit reticulocytes; Cox RA et al.; Mg2+ was shown to affect the conformation of rRNA over the range of 0.03-1.2M-KCl . The species studies were Escherichia coli S-rRNA and L-rRNA (the RNA moieties of the smaller and larger subribosomal particles respectively) and rabbits S-rRNA and L-rRNA . 2 . The addition of Mg2+ to rRNA in reconstitution buffer (0.35M-KCl0.01M-Tris/HCl, pH7.2) at 20 degrees C let to an increase in bihelical secondary structure through the formation of additional (mainly A-U) base-pairs (e.g . an additional approx . 58 A-U base-pairs per molecule of E . coli S-rRNA as judged by u.v . difference spectrophotometry... Experientia, 1976 Dec 15, 32(12), 1572 - 3 Arabinose nucleoside triphosphates are no inhibitors for DNA-dependent RNA polymerases; Muller WE; 1-Beta-D-arabinofuranosylcytosine-5' -triphosphate and 9-beta-D-arabinofuranosyladenosine-5' -triphosphate were found to have no inhibitory potency for both mammalian DNA-dependent RNA polymerase II and E . coli DNA-dependent RNA polymerase. Biochim Biophys Acta, 1976 Dec 14, 455(3), 889 - 99 Release of outer membrane fragments from normally growing Escherichia coli; Hoekstra D et al.; A complex containing lipopolysaccharides, phospholipids and proteine separated from the medium by gelfiltration on Sephadex G-200 or by centrifugation . Electron microscopy revealed that this material is released as vesicles and membrane fragements . To determine the origin of these fragments, they were compared to outer and cytoplasmic membranes with respect to keto-deoxyoctulosonic acid, phospholipid, and protein content, phospholipid composition, fatty acid composition, protein distribution on sodium dodecyl sulfate-polyacrylamide gels, buoyant density, and content of several membrane marker enzymes . The results of this comparison indicate that the membrane fragments found in the culture supernatant of normally growing Escherichia coli consist of practically unmodified outer membrane . Possible mechanisms as to the cause of the release of outer membrane fragments, and its relationship to cell-division, are discussed. Biochemistry, 1976 Dec 14, 15(25), 5474 - 80 Demonstration of ribosome-dependent photoinduced chain breakage of the 16S ribosomal ribonucleic acid component of the Escherichia coli 30S ribosomal subunit; Gorelic L; The effects of 253.7-nm radiation on the structural integrities of free and ribosome-bound 16S ribosomal ribonucleic acid (rRNA) have been elucidated . Exposure of aqueous solutions of Escherichia coli 30S ribosomal subunits to 253.7-nm radiation results in RNA-chain scission and the formation of single-stranded breaks in double-stranded regions of the ribosome-bound 16S rRNA . The minimum doses of incident 253.7-nm radiation required for the first detection of the two types of RNA chain breaks are 2 X 10(20) quanta for single-strand breaks in double-stranded regions of the ribosome-bound 16S rRNA,and at least 5 X 10(20) quanta for RNA-chain scission . In contrast to the photosensitivity of ribosome-bound 16S rRNA toward chain breakage, free 16S rRNA seems to be resistant toward photoinduced chain breakage at doses of incident 253.7-nm radiation up to at least 10(21) quanta. Biochim Biophys Acta, 1976 Dec 13, 454(3), 429 - 35 Hybridization of bean chloroplast transfer RNAs to chloroplast DNA; Steinmetz A et al.; Bean (Phaseolus vulgaris) chloroplast tRNAsLeu and tRNAsPhe hybridize to chloroplast DNA, whereas the corresponding cytoplasmic tRNA species do not, suggesting that chloroplast transfer RNAs are coded for by chloroplast DNA . The hybridization of the three chloroplast tRNAsLeu or of the two tRNAsPhe isoacceptors is not additive, and the isoacceptors compete with each other in the hybridization to chloroplast DNA, suggesting that these isoacceptors are coded for by the same gene(s) and differ only in the extent of post-transcriptional modification . Although hererologous aminoacylation reactions and comparisons of base composition suggest a resemblance between chloroplast and procaryotic tRNAs, only a slight cross hybridization reaction was observed between chloroplast and Escherichia coli leucyl- or phenylalanyl-tRNAs and DNAs. Biochim Biophys Acta, 1976 Dec 13, 454(3), 558 - 66 Main binding sites of the carcinogen, 4-nitroquinoline 1-oxide in nucleic acids; Tada M et al.; 4-Hydroxyaminoquinoline 1-oxide, the reduced metabolite of 4-nitroquinoline 1-oxide, was reacted with homopolyribonucleotides through the catalysis of an activating enzyme . It bound specifically to poly(G), poly(A) and poly(X) but negligibly to poly(C), poly (U) and poly(I) . Chromatographic analysis of the acid hydrolysates of carcinogen-bound polynucleotides revealed that the reaction of the carcinogen with polynucleotides yielded two guanine, one adenine and two xanthine adducts . The same kinds of guanine and adenine adducts were found in DNA or RNA isolated from Escherichia coli and mammalian cells that had been exposed to the carcinogen . Analysis of nucleic acids isolated from 4-hydroxyaminoquinoline 1-oxide-treated cells revealed that 4-hydroxy-aminoquinoline reacts in vivo preferentially with guanines, to a less, but significant, extent with adenines and not significantly with pyrimidines. Biochim Biophys Acta, 1976 Dec 13, 454(3), 567 - 77 The sucrose gradient and native DNA S20,W, an examination of measurement problems; Clark RW et al.; Sedimentation coefficients of T7, T2H AND T4 DNA were determined with isokinetic sucrose gradients in both 0.1 M and 1 M NaCl . The s values were completely equivalent to those measured by analytical ultracentrifuge and no reduction of s20,w was observed due to the presence of sucrose (anomalous sedimentation) . s20,w values are calculated on the basis of both partial specific volume (v) and apparent specific volume (0) . Using the latter value s20,w molecular weight relations are derived for 0.1 M and 1 M NaCl solvents . The glucosylation of T2H and T4 DNA appears to influence s20,w in a manner disproportionate to the molecular weight added by glucose. Biochim Biophys Acta, 1976 Dec 13, 454(3), 504 - 13 Effect of stringent and relaxed control on transcription of the tryptophan operon from the ptrp promoter and the PL promoter in trp phage; Kuwano M et al.; Tryptophan (trp) mRNA synthesis from the authentic trp promoter (Ptrp) is apparently arrested upon translation blockage, while trp mRNA synthesis as a result of read-through from the Pl promoter of the N gene in trp phage is not so affected . When translation is blocked at a nonpermissive temperature in the temperature-sensitive mutants of Escherichia coli rel carrying altered ribosomal elongation factors G (strain CP78G) and Ts (strain HAK88), CP78G and HAK88 show relaxed and stringent phenotypes respectively in control of RNA synthesis . Under conditions causing translation blockage in both mutants, Pl-promoted synthesis of trp mRNA is not depressed while Ptrp-promoted synthesis of trp mRNA is blocked . The insensitivity of Pl-promoted transcription of the translocated trp operon to stringent control is also confirmed by using a strain 10b6s rel carrying a temperature-sensitive valyl-tRNA synthetase . In contrast to the above observation, transcription of the trp operon from either the Pl and Ptrp promoters in a 10b6r rel infected with trp is inhibited greatly at the nonpermissive temperature . This effect occurs even if the level of trp transcription observed at 30 degrees is already low, thus suggesting that translational machinery is intrinsically abnormal in the rel strain. Biochim Biophys Acta, 1976 Dec 13, 454(3), 469 - 79 Characterization of the RNA transcribed in vitro from native mammalian DNA by Escherichia coli RNA polymerase; Alonso A et al.; High-molecular-weight native mouse DNA was transcribed with Escherichia coli RNA polymerase under low salt conditions, and the nature of the DNA sequences transcribed determined by molecular hybridization . The results indicated that E . coli RNA polymerase does not transcribe the sequences in native mouse DNA randomly under these conditions . First, hybridization with a large excess of mouse DNA showed that no more than 5% of the RNA synthesized had been transcribed from repeated sequences in the DNA . Second, hybridization with tracer amounts of labelled non-repeated mouse DNA indicated that the bulk of the RNA had been transcribed from less than 1% of the non-repeated sequences and only about 10% had been transcribed from a further 25% of these sequences; the remaining non-repeated sequences in the DNA, amounting to 50% of the genome, were not represented in the RNA synthesized in vitro to any detectable extent . Third, the proportion (40%) of complementary DNA transcribed from mouse-liver nuclear polyadenylated RNA which hybridized with the RNA synthesized in vitro was significantly greater than would have been expected if transcription had been random . The data have also been interpreted as indicating the presence of two types of initiation site for E . coli RNA polymerase in the non-repeated sequences in mouse DNA . The frequencies of their occurrence have been calculated to be one per 150 000 base-pairs and one per 500 base-pairs, respectively. Eur J Biochem, 1976 Dec 11, 71(2), 509 - 18 Symmetry and asymmetry of the pyruvate dehydrogenase complexes from Azotobacter vinelandii and Escherichia coli as reflected by fluorescence and spin-label studies; Grande HJ et al.; Fluorescence-lifetime measurements of FAD bound to lipoamide dehydrogenase from Azotobacter vinelandii and Escherichia coli were performed . It is shown from these results that the two FAD groups in the isolated dimeric enzyme, as well as in the enzyme in the intact complex of E . coli, are in non-equivalent surroundings . This contrasts with the near equivalence of the FAD groups of both the enzyme and complex isolated from A . vinelandii . Reduction of the complex with Mg2+, thiamine pyrophosphate and pyruvate or with NADH enables the attachment of a maleimide analogue specifically to the lipoyl moieties of the transacetylase(s) . Spin label {N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)maleimide} introduced in such a way proves the existence of at least two different micro-environments around the lipoyl moieties in complex isolated from A . vinelandii . Electron paramagnetic resonance spectra of the specifically spin-labelled complexes from E . coli and A . vinelandii, when dissolved in tricine {N-tris(hydroxymethyl)-methylglycine} buffer, show interactions of at least two electron spins with each other, which indicate that the lipoyl moieties are rather close together . Fluorescent label {N-(1-anilinonaphthyl-4)maleimide} is specifically attached to the lipoyl moiety of the high-Mr transacetylase of the freshly isolated complex from A . vinelandii . From the large differences in the apparent lifetimes tau p and tau m, as detected by phase fluorimetry, it is shown that this fluorscent label is distributed in different micro-environments . The differences observed in energy transfer between fluorescent label, attached to the lipoyl moiety of the high-Mr transacetylase, indicate different conformations of the complex from A . vinelandii . Upon introduction of the label after reduction with NADH a much larger energy transfer, thus a shorter distance, is observed between the label and FAD than when reduction is performed with Mg2+, thiamine pyrophosphate and pyruvate . A similar conformation dependence upon reduction is found for the pyruvate dehydrogenase complex from E . coli . It is thus proposed that the transacetylase of E . coli and the high-Mr transacetylase of A . vinelandii are both non-symmetrically distributed within the complex. Eur J Biochem, 1976 Dec 11, 71(2), 483 - 91 Characterization and site of action of a soluble protein that stimulates peptide-bond synthesis; Glick BR et al.; A recently identified soluble protein, named EF-P, stimulates peptide bond synthesis from ribosomal-bound N-formylmethionyl-tRNA and the aminoacyl-tRNA analog, puromycin . Using this model of peptide bond formation we have purified this activity approximately 100-fold from ribosome-free extracts of Escherichia coli . In order to study the mechanism by which the EF-P factor stimulates peptide bond formation, we examined and compared the requirements and site of action of the spontaneous and the EF-P-mediated synthesis of peptide bonds . We find that "enzymic" peptide bond synthesis (+EF-P) is characterized by relatively broad temperature and NH4Cl optima, a sharp Mg2+ optimum at 12 mM, and an apparent pKa of approximately 8.5 . The characteristics of enzymic peptide bond synthesis closely resemble those reported for native peptidyl-puromycin formation rather than other models of peptide synthesis . Factor EF-P requires both 30-S and 50-S subunits for activity . The 30-S particle is inactive by itself and may function in the reaction merely to bind the fMet-tRNA substrate . Both the peptidyl transferase and the EF-P binding site may be part of the 50-S subunit . Unlike all other propagation factors, EF-P does not require the 50-S ribosomal proteins L7 and L12 and may therefore occupy a different ribosomal site. Eur J Biochem, 1976 Dec 11, 71(2), 459 - 67 Enzyme-linked sandwich immunoassay of macromolecular antigens using the rabbit antibody-coupled glass rod as a solid phase; Hamaguchi Y et al.; A highly sensitive sandwich immunoassay of macromolecular antigens using the rabbit antibody Fab' - beta-D-galactosidase complex and the rabbit antibody immunoglobulin-G-coupled glass rod as a solid phase is described . The Fab' fragments of rabbit antibody IgG are conjugated with beta-D-galactosidase from Escherichia coli using N,N'-o-phenylenedimaleimide . Rabbit antibody IgG is coupled to the aminoalkylsilyl glass rods (3 mm in diameter and 5 mm in length) using glutaraldehyde . A wide range of the concentrations of rabbit IgG fraction (20-2000 mug/ml) is effective for coupling, and the amount of rabbit immunoglobulin G coupled can be controlled . The smallest amounts of ornithine delta-aminotransferase from rat liver, human immunoglobulin G and 2,4-dinitrophenyl human immunoglobulin G that can be determined are 0.03, 0.3 and 0.04 fmol, respectively . The sensitivity of the assay for these antigens is affected mainly by the non-specific binding of the complexes to the solid phase and the ability of antigen molecules, adsorbed on the solid phase, to bind specifically the complexes . The assay with the rabbit antibody immunoglobulin-G-coupled glass rods is simpler and more sensitive than that with the rabbit antibody immunoglobulin-G-coupled Sepharose 4B. Eur J Biochem, 1976 Dec 11, 71(2), 437 - 42 Thermodynamic studies on the specificity of L-isoleucine-tRNA ligase of Escherichia coli MRE 600 . Calorimetric investigations on binding of amino acids and isoleucinol to the enzyme; Hinz HJ et al.; The association enthalpies, delta Ha, involved in the reactions between L-isoleucine:tRNA ligase (AMP-forming) from Escherichia coli MRE 600 (EC 6.1.1.5) and various amino acids have been determined calorimetrically in 50 mM potassium phosphate buffer, at pH 7.5, in the presence of 1 mM dithioerythritol . The delta Ha values for binding of L-isoleucine, L-leucine, L-valine, L-norvaline and L-2-amino-3S, 4-dimethyl pentanoic acid agree within the limits of experimental error in magnitude (3.7 +/- 0.9 kcal mol-1 or 15.5 +/- 3.8 kJ mol-1 at 25 degrees C) and variation with temperature (delta cp = -430 +/- 20 cal mol-1 K-1 or 1799 +/- 84 J mol-1 K-1) . In view of the large differences in the equilibrium constants for the corresponding binding equilibria, the identical association enthalpies suggest that the enthalpic contribution to the Gibbs free energy of binding, delta Ga, cannot be responsible for the specificity of the interaction of the enzyme with the amino acids . It has rather to be inferred that the entropic term, delta Sa, is decisive in discriminating the correct amino acid . Analogous calorimetric binding studies on the reaction between L-isoleucinol and the enzyme suggest that the absence of the carboxyl group renders the association enthalpy more positive (by 4-5 kcal mol-1 or 16.7-20.9 kJ mol-1) with respect to that of the amino acids . The variation with temperature of the delta Ha values, however, practically parallels that of the amino acids. Eur J Biochem, 1976 Dec 11, 71(2), 327 - 36 Chorismate mutase/prephenate dehydratase from Escherichia coli K12 . 2 . Evidence for identical subunits catalysing the two activities; Gething MJ et al.; On the basis of amino acid composition, tryptic fingerprints and the determination of amino acid sequences around the four cysteine residues, it can be concluded that chorismate mutase/prephenate dehydratase from Escherichia coli K12 consists of identical, or closely similar subunits . It follows from this that the mutase and dehydratase activities of the enzyme are probably catalysed on the one subunit. Eur J Biochem, 1976 Dec 11, 71(2), 317 - 25 Chorismate mutase/prephenate dehydratase from Escherichia coli K12 . 1 . The effect of NaCl and its use in a new purification involving affinity chromatography on sepharosyl-phenylalanine; Gething MJ et al.; A new simplified procedure for the purification of chorismate mutase/prephenate dehydratase, based on affinity chromatography on Sepharosyl-phenylalanine, has been developed . The method utilizes the effect of NaCl on the binding properties of the enzyme . NaCl inhibits both the mutase and dehydratase activities of the enzyme . In each case this inhibition is cooperative indicating homotropic interactions between NaCl binding sites on the enzyme . In addition NaCl induces homotropic cooperative effects between chorismate binding sites and between prephenate binding sites . NaCl also increases the sensitivity of the enzyme to inhibition by phenylalanine. Eur J Biochem, 1976 Dec 11, 71(2), 577 - 83 Terminal riboadenylate transferase from Escherichia coli . Characterization and application; Sano H et al.; Catalytic properties of terminal riboadenylate transferase from Escherichia coli and the products of the enzymic reaction were investigated . The kinetic analysis revealed that the reaction obeys the sequential ordered bi-bi mechanism . The application of conditions elaborated in this study resulted in the synthesis of products of defined size and efficient primer utilization . The tRNA(rA)n obtained was a good template for the synthesis of complementary DNA with reverse transcriptase. Eur J Biochem, 1976 Dec 11, 71(2), 443 - 9 Interaction of DNA with DNA-binding proteins . The characterization of protein HD from Escherichia coli and its nucleic acid complexes; Berthold V et al.; DNA-binding protein HD with a monomer molecular weight of 9000 was isolated from Escherichia coli cells . The protein occurs as a tetramer under native conditions and binds to single and double-stranded DNA and also to RNA . DNA complexed with protein HD is a poor template for DNA synthesis by E . coli polymerase I, II or III holoenzyme . Exonuclease III is hindered in degrading HD-protein-covered double-stranded DNA, whereas exonuclease I can digest complexed single-stranded DNA . Transcription is liqhtly stimulated in the presence of protein HD. J Biol Chem, 1976 Dec 10, 251(23), 7709 - 16 Nucleotide sequence and in vitro processing of a precursor molecule to Escherichia coli 4.5 S RNA; Bothwell AL et al.; A precursor molecule to the stable 4.5 S RNA species of Escherichia coli has been found to accumulate at 42 degrees in a strain thermosensitive for the function of ribonuclease P . The precursor molecule is 130 nucleotides long . Twenty-two extra nucleotides, starting with pppGp, precede the mature sequence at its 5' terminus . At least 1 extra uridine residue can be found at the 3' terminus . The precursor to 4.5 S RNA is cleaved in vitro by RNase P to generate a 5' end identical to that of the mature 4.5 S RNA. J Biol Chem, 1976 Dec 10, 251(23), 7577 - 80 Disappearance of specific proteins from the membranes of colicin-treated cells; Knepper JE et al.; Two colicins that affect energy metabolism in Escherichia coli (colicins K and E1) are shown to cause loss of specific membrane proteins from treated cells . Disappearance of these proteins after treatment with colicin K occurs at low multiplicities and is independent of ATPase (EC 3.6.1.4) and phospholipase A (EC 3.1.1.4) activities . The uncouplers carbonyl cyanide m-chlorophenylhydrazone and dinitrophenol do not alter the pattern of membrane proteins. Mycopathologia, 1976 Dec 10, 60(1), 57 - 62 Methylation and aging in Rhizoctonia solani; Gottlieb D et al.; Our earlier studies had shown that as fungi age, many of their vital functions decrease; in Rhizoctonia solani, protein synthesis is one of the functions so affected . We now find that the ability to methylate tRNA, a vital component of the protein synthesizing system, also decreases with age . This methylation of Escherichia coli tRNA by R . solani methylase preparations increased with the concentration of enzyme and with time of incubation; in both cases the rate of increase was considerably higher for preparations from young cells than for those from old cells . The methylation reaction also increased with the concentration of substrate tRNA, with temperature, at least to 45 degrees C, and with pH to 9.0 . Methylase preparations from R . solani methylated both exogenous E . coli tRNA and yeast tRNA, but were only weakly active on isolated R . solani tRNA . However, acid-precipitated methylases from R . solani were very effective in methylating the homologous exogenous tRNA . Regardless of the source of the tRNA used as substrate, the methylases from older cells were always less active than those from young cells from the same mycelium . No methylase inhibitor was detected in the fungus. J Biol Chem, 1976 Dec 10, 251(23), 7669 - 74 A new endoribonuclease from Escherichia coli . Ribonuclease N; Misra TK et al.; A new ribonuclease called RNase N was isolated from Escherichia coli . It is a nonspecific endoribonuclease that can cleave rRNA, poly(U), and poly(C) to small oligonucleotides and 5'-mononucleotides . It requires monovalent cations and is inhibited by divalent cations . It is suggested that this enzyme plays a role in the decay of rRNA,under various starvation conditions and perhaps in the decay of mRNA. J Biol Chem, 1976 Dec 10, 251(23), 7530 - 8 Catalytic mechanisms of glutamine synthetase enzymes . Studies with analogs of possible intermediates and transition states; Wedler FC et al.; Glutamine synthetase enzymes isolated from pea seeds and from Escherichia coli are observed to behave differently in experiments designed to probe reaction mechanism . Although both enzymes were found to bind and release substrates in random order mechanisms (Wedler, F.C . (1974) J . Biol . Chem, 247, 5080-5087), isotopic exchanges with partial reaction systems indicative of a gamma-glutamylphosphate intermediate are catalyzed only by the pea seed enzyme . The E . coli system fails to catalyze any exchanges at appreciable rates unless all substrates are present . This negative result implies either an absolute conformational requirement for bound substrates or that the putative complex (E-Glu-P-MgADP) is exceedingly tight . To test the latter, a nonreactive structural analog of gamma-glutamyl-phosphate, namely 3-(phosphonoacetylamido)-L-alanine (PA2LA), has been synthesized . With the E . coli enzyme PA2LA was found to bind no more tightly than L-glutamate and is strictly competitive versus L-glutamate (Ki = 3 mM) . Thus, failure to catalyze partial exchange reactions indicative of gamma-Glu-P is probably not attributable to tight complex formation . The binding of PA2LA with the pea seed enzyme apparently involves a two-step process: a rapid, reversible step in which PA2LA binds 10-fold more tightly than L-glutamate, followed by a slow (but reversible) process involving very tight PA2LA binding, apparently with enzyme isomerization promoted by nucleotide . The specificity of the two enzymes toward L-methionine-SR-sulfoximine, Met(O)(NH), was also different... Mol Gen Genet, 1976 Dec 8, 149(2), 225 - 8 Identity of a gene responsible for suppression of aminoacyl-tRNA synthetase mutations with rpsT, the structural gene for ribosomal protein S20; Buckel P; Sepcialized transducing lines of phage lambda carrying segments between thr and car from the E . coli chromosome have been isolated . With help of these phages it has been shown that the gene sups20 (Bock et al., 1974) corresponds to rpsT, the structural gene for ribosomal protein S20. Mol Gen Genet, 1976 Dec 8, 149(2), 201 - 10 Revertants from RNase III negative strains of Escherichia coli; Apirion D et al.; E . coli strains carrying the rnc-105 allele do not show any level of RNase III in extracts, grow slower than rnc+ strains at temperatures up to 45 degrees C and fail to grow at 45 degrees C . Revertants which can grow at 45 degrees C were isolated . The vast majority of them still do not grow as fast as rnc+ strains and did not regain RNase III activity . The mutation(s) which caused them are suppressor mutations (physiological suppressors) which do not map in the immediate vicinity of the rnc gene . A few of the revertants regain normal growth, and contain normal levels of RNase III . They do not harbor the rnc-105 allele and therefore are considered to be true revertants . By using purines other than adenine it was possible to isolate rnc + pur- revertants from an rnc- pur- strain with relative ease . They behaved exactly like the true rnd+ revertants isolated from rns- strains at 45 degrees C . A merodiploid strain which contains the rnc+ gene on an episome behaves exactly like an rnc+ strain with respect to growth and RNA metabolis, eventhough its specific RNase III activity is about 60% of that of an rnc+ strain; thus the level of RNase III is not limiting in the cell . The rnc- strains show a characteristic pattern of transitory molecules, related to rRNA, 30S, 25S, "p23" and 18S, which are not observed in rnc+ strains . This pattern is unchanged in rnc- strains and in the revertants which are still lacking RNase III, regardless of the temperature in which RNA synthesis was examined (30 degrees to 45 degrees C) . On the other hand, in the rnc+ strains as well as in the true revertants and the rnc+/rnc- merodiploid, the normal pattern of p16 and p23 is observed at all temperatures . These findings suggest that all the effects observed in RNase III- strains are due to pleiotropic effects of the rnc-105 allele, and that the enzyme RNase III is not essential for the viability of the E . coli cell. Mol Gen Genet, 1976 Dec 8, 149(2), 151 - 8 REPLICAtion of small plasmids in extracts of Escherichia coli: requirement for both DNA polymerases I and II; Staudenbauer WL; The role of the three E . coli DNA polymerases (pol I, II, and III) in the replication of Col E1 DNA and other small plasmids with similar replicative properties was investigated in a soluble in vitro system prepared by freeze-thaw lysis of chloramphenicol-treated cells (Staudenbauer, 1976) . Extracts from isogenic mutants of the polA, polB and polC gene loci deficient in pol I, II, and III respectively were examined for their replicative capacity . It was found that polA and polC extracts are deficient in the synthesis of supercoiled plasmid DNA, whereas the polB mutation has not effect . Deficient extracts could be complemented by addition of purified pol I and pol III holoenzyme . Analysis of the in vitro synthesized DNA by alkaline gradient centrifugation indicates that pol I is involved in an early step of the replication cycle whereas pol III is required at a later stage . These conclusions are confirmed by inhibition studies employing arabionsylcytosine triphosphate (aCTP) which is shown to interfere with pol III as well as pol II . The strong inhibitory effect of aCTP on plasmid replication is not influenced by the polB mutation and mimicks the effects of thermal inactivation of polC extracts . It is suggested that aCTP blocks plasmid ENA replication in vitro by interfering with pol III function Mol Gen Genet, 1976 Dec 8, 149(2), 135 - 43 Gal mRNA initiated within IS2; Rak B; A strain of E . coli carrying IS2 in the control region of the gal operon has been found to revert to a constitutive phenotype . These revertants can be divided into two classes, which differ in their rate of enzyme synthesis and gal transcription . One revertant synthesizes the gal messenger at a low level (low level revertants), the other at a higher level that exceeds that of the induced wild type two- to three-fold (high level revertants) . In both cases it has been shown that the gal messenger is covalently bound to IS2-RNA, which is transcribed from IS2 in the original orientation . The evidence suggests, that the section of the IS2-element, from which this RNA is transcribed in the case of the high level revertants is smaller than 50 nucleotides long: i.e . the resolution of the hybridization method used for the detection of sequence homologies exceeds that of the electron microscopical heteroduplex technique. Biochim Biophys Acta, 1976 Dec 8, 452(2), 625 - 8 The incorporation of tritium from tritium-enriched water into UDP-N-acetylglucosamine and UDP-N-acetylmannosamine catalyzed by UDP-N-adetylglucosamine 2-epimerase from Escherichia coli; Salo WL; Uridine diphosphate N-acetylglucosamine 2-epimerase from Escherichia coli 014 K7 H- catalyzes the reversible epimerization of uridine diphosphate N-acetylglucosamine to uridine diphosphate N-acetylmannosamine . During epimerization, tritium from tritium-enriched water is incorporated into both uridine diphosphate N-acetylglucosamine and uridine diphosphate N-acetylmannosamine . The position of incorporation is C-2 of the N-acetylhexosamine moieties. Biochim Biophys Acta, 1976 Dec 8, 452(2), 566 - 79 Phosphoenolpyruvate carboxylase of Escherichia coli . Studies on multiple conformational states elicited by allosteric effectors with a fluorescent probe, 1-anilinonaphthalene-8-sulfonate; Yoshinaga T; Conformational change of phosphoenolpyruvate carboxylase (orthophosphate: oxaloacetate carboxy-lyase (phosphorylating), EC 4.1.1.31) induced by allosteric effectors was investigated using a hydrophobic probe, 1-anilinonaphthalene-8-sulfonate (ANS) . Kinetic experiments suggested that ANS binds with the enzyme at the sites which are not involved in the catalytic and regulatory functions, though it partially inhibits the enzyme activity with half-saturation concentration (S0.5) of 38.5 muM . Binding experiments showed that a maximum of 2 mol of ANS are able to bind with 1 mol of the enzyme subunit presumably with an equal dissociation constant to each other (34.5 muM) . Flourescence emission of ANS was markedly increased by binding with the enzyme . L-Aspartate, the allosteric inhibitor, and CoASAc and fructose 1,6-bisphosphate (Fru-1,6-P2) the allosteric activators, produced various degrees of change in fluorescence, when added singly or in combinations . The changes were shown to be attributable to the allosteric interactions between the enzyme and effectors from some criteria such as structural specificity, half-saturation concentrations, and heterotropic-homotropic interactions of the ligands . It was concluded from these analyses that the enzyme can be in at least four conformational states which are distinct from each other . Especially noteworthy is the finding that the enzyme, upon simultaneous binding of CoASAc and Fru-1,6-P2, takes a new conformation which is enterely different from those induced by sole binding of each effector . In addition, the heterotropic interaction between the activator and the inhibitor was observed through conformational change by the ANS method, as observed in the kinetic studies. Mol Gen Genet, 1976 Dec 8, 149(2), 229 - 37 Biochemical, genetic, and regulatory studies of alanine catabolism in Escherichia coli K12; Franklin FC et al.; E . coli K12 was found to utilise both D-and L-stereoisomers of alanine as sole sources of carbon, nitrogen and energy for growth . This capability was absolutely dependent upon the possession of an active membrane-bound D-alanine dehydrogenase, and was lost by mutants in which the enzyme was defective . The Michaelis constant for the enzyme with D-alanine as substrate was 30 mM, and the pH optimum about 8.9 . D-alanine was the most active substrate, L-alanine was inactive and several other D-amino acids were 10--50% as active as D-alanine . Oxidation of D-alanine was linked to oxygen via a cytochrome-containing respiratory chain . Synthesis of the dehydrogenase was induced 16 to 23-fold by incubation with D- or L-alanine, but only D-alanine was intrinsically active as an inducer . L-alanine was active either as a substrate or inducer only in t he presence of an uninhibited alanine racemase which converted it to the D-isomer . The map-location of their structural genes between ara and leu, together with other similarities, indicate that D-alanine dehydrogenase and the "alaninase" of Wijsman (1972a) are the same enzyme . Both D- and L-alanine were intrinsically active as inducers of alanine racemase synthesis . The synthesis of both D-alanine dehydrogenase and alanine racemase was found to be regulated by catabolite repression. Biochim Biophys Acta, 1976 Dec 6, 449(3), 401 - 11 An evaluation of N-phenyl-1-naphthylamine as a probe of membrane energy state in Escherichia coli; Cramer WA et al.; Colicin El and the uncoupler of oxidative phosphorylation, trifluoromethoxy-carbonylcyanidephenylhydrazone (FCCP), cause an increase in the fluorescence intensity of N-phenyl-1-naphthylamine bound to whole cells of Escherichia coli . It has been shown elsewhere that this fluorescence increase correlates well with de-energization . Addition of glucose causes a large cyanide-sensitive decrease of intensity, tentatively associated with energization, with the emission spectrum almost returning to the original trace with a peak at 417 nm . These data suggest that there may be a measurable competition between de-energization and energization of the cell membrane, and that the probe fluorescence intensity may be a general indicator of membrane energy level . The conclusions reached about cellular energy level from measurements of the probe fluorescence intensity correlate partly (a, b below, not c) with the energy level assayed physiologically through rates of active transport; (a) FCCP is found to be a poor inhibitor of proline transport if cells are first incubated with glucose, showing eutger cinpetition between the processes of energization and de-energization or an increase in the envelope permeability barrier to FCCP caused by glucose addition . (b) Cyanide blocks the fluorescence decrease caused by glucose and inhibits proline and serine transport, consistent with the decrease in probe fluorescence intensity indicating an increase in membrane energization . However, (c) it appears that the amplitude of the fluorescence intensity decrease caused by glucose addition in the presence of FCCP and colicin E1 greatly exaggerates the extent of real membrane energization . Glucose added after uncoupler can cause only a small increase, and after colicin, a negligible increase in the proline transport rate, indicating that the magnitude of the fluorescence intensity decrease after glucose addition is not a true measure of membrane energization, but rather seems to amplify this energization greatly . Glucose addition does not cause a decrease in fluorescence intensity in cells treated with EDTA to remove lipopolysaccharide and an apparent barrier to the probe . The rotational relaxation time of the probe in intact cells appears to correlate somewhat better with the cellular energy level than does intensity. Biochim Biophys Acta, 1976 Dec 6, 449(3), 376 - 85 Mutations affecting the reduced nicotinamide adenine dinucleotide dehydrogenase complex of Escherichia coli; Young IG et al.; A strain carrying a point mutation affecting the NADH dehydrogenase complex of Escherichia coli has been isolated and its properties examined . The gene carrying the mutation (designated ndh) was located on the E . coli chromosome at about minute 23 and was shown to be cotransducible with the pyrC gene . Strain carrying the ndh- allele were found to be unable to grow on mannitol and to grow very poorly on glucose unless the medium was supplemented with succinate, acetate or casamino acids . The following properties of strains carrying the ndh- allele were established which suggest that the mutation affects the NADH dehydrogenase complex but apparently not the primary dehydrogenase . Membrane preparations possess normal to elevated levels of D-lactate oxidase and succinate oxidase activities but NADH oxidase is absent . NADH is unable to reduce ubiquinone in the aerobic steady state and reduces cytochrome b very slowly when the membranes become anaerobic . NADH dehydrogenase, measured as NADH-dichlorophenolindophenol reductase is reduced but not absent . NADH oxidase is stimulated by menadione although not by Q-3 or MK-1 and in the presence of menadione, cytochrome b is reduced normally by NADH . Further mutants affected in NADH oxidase were isolated using a screening procedure based on the growth characteristics of the original ndh- strain . The mutantions carried by these strains were all cotransducible with the pyrC gene and the biochemical properties of the additional mutants were similar to those of the original mutant . The properties of the group of ndh- mutants established so far suggest that they are affected in the transfer of reducing equivalents from the NADH dehydrogenase complex to ubiquinone. Biochim Biophys Acta, 1976 Dec 2, 455(2), 412 - 32 Correlated x-ray diffraction and freeze-fracture studies on membrane model systems . Perturbations induced by freeze-fracture preparative procedures; Costello MJ et al.; Lipid-water and protein-lipid-water phases have been examined by X-ray methods before and after freezing . Frozen samples have been subsequently fractured and replicated, thus permitting an evaluation of the nature of structural perturbations in samples examined by freeze-fracture electron microscopy . Important results are summarized: (1) Freezing low water content (approx . less than 25%) phases causes perturbations in the packing of hydrocarbon chains . The results suggest that freezing liquied paraffin chains produces a condensed "glass-like" packing . (2) Additional perturbations occur in high water content samples . After freezing, much smaller lamellar repeat distances, intense ice reflections, and extensive perturbation of fracture faces are consistant with the expulsion of water from between lamellae . Presence of glycerol generally relieves these perturbations but in some cases introduces additional lattice disorder . (3) Surprisingly, cooling by a stream of cold N2 gas (-140 degrees C) produces qualitatively the same results as rapid cooling in liquid Freon-22 (-160 degrees C) . (4) Complex perturbations occur in phases containing integral membrane proteins . Interesting results have been obtained with cytochrome b5-lecithin lamellar associations which display both smooth and rough fracture faces without clearly defined particles. Arch Biol Med Exp (Santiago), 1976 Dec, 10(1-3), 78 - 84 Microinjection of tRNA into amphibian oocytes; Allende JE et al.; The microinjection technique affords us the possibility to introduce purified components into living cells and to answer the question of what effects the change introduced has on cellular metabolism . This technique can therefore be used to test the hypothesis that transfer RNA plays a regulatory role in cellular protein synthesis . Prior to these experiments it is important, however, to test whether transfer RNA microinjected into amphibian oocytes is stable and functional inside this cells . These two questions are answered affirmatively in this report . The stability of tRNA was tested by following the content of TCA precipitable counts inside the oocytes at different times after microinjection of radioactive yeast and E . coli tRNA and by polyacrilamide gel electrophoresis of the material recovered from the cell . The results clearly indicate that tRNAs are resistant to the action of occyte ribonucleases that degrade other RNAs such as 5S RNA . The functionality of the injected tRNA was tested by assaying the intracellular aminoacylation of microinjected yeast tRNA . The aminoacylation of bulk yeast (3H) tRNA introduced into Xenopus laevis oocytes was tested by the capacity of the material recovered 5 hours after injection into the cell to form a ternary complex with wheat protein synthesis elongation factor 1 and GTP . The complex only forms with aminoacyl-tRNA and not with unacylated tRNA . This method showed that at least 80% of the tRNA introduced into the cell was aminoacylated in vivo . A direct assay for internal aminoacylation made use of microinjection of pure tRNAPhe and subsequent determination by phenol extraction of (14C)Phe-tRNA content of oocytes that had been incubated for 2 hours in a medium containing (14C)phenylalanine . The results obtained showed that the oocytes could internally aminoacylate 200-500 times more tRNAPhe that the cell normally contains . Appropiate controls demonstrated that the aminoacylation was aminoacid and tRNA specific and that periodate oxidized tRNAPhe could not be in vivo aminoacylated but tRNAPhe deprived of its Y base could accept the aminoacid . A brief study demonstrated that bulk yeast tRNA and tRNAPhe without its Y base did not inhibit endogenous protein synthesis but a similar amount of tRNAPhe caused 50% inhibition and periodate-oxidized tRNAPhe a 95% inhibition. Nucleic Acids Res, 1976 Dec, 3(12), 3359 - 67 End group of naturally terminated and UV lesion terminated T7 in vitro RNA; Ali R et al.; The 3' terminal nucleosides of RNA transcribed in vitro by E . coli RNA polymerase from T7 DNA and UV irradiated TN DNA were determined . The 3' terminal nucleoside of naturally terminated (t1 termination site) RNA cytidine . In the case of RNA terminated at UV lesions, it is cytidine in 0 per cent of the molecules and adenosine in the remaining 30 per cent . Cytidine trialcohols are labile in high concentrations of KOH and at high temperature and appear to convert to uridine. J Biochem (Tokyo), 1976 Dec, 80(6), 1411 - 22 Effects of heating in dodecyl sulfate solution on the conformation and electrophoretic mobility of isolated major outer membrane proteins from Escherichia coli K-12; Nakamura K et al.; Major outer membrane proteins of Escherichia coli K-12 with apparent molecular weights ranging from 30,000 to 40,000 were resolved into four distinct bands by electrophoresis on an improved urea-sodium dodecyl sulfate (SDS)-polyacrylamide gel containing a high concentration of N,N'-methylenebisacrylamide . The electrophoretic mobilities of three of these proteins, O-8, O-9, and O-10, changed when they were heated in SDS solution . Proteins O-8, O-9, and O-10, were purified to near homogeneity without heating in SDS solution . Electrophoretic profiles of the purified proteins changed depending on the solubilization temperature in SDS solution . Infrared and CD spectra of these proteins revealed that they were extremely rich in beta-structured polypeptide, which is stable in SDS solution at room temperature . On the other hand, CD spectra typical of alpha-helix structure were obtained when the proteins were heated in SDS solution, indicating that a gross conformational change occurred in the protein molecules upon heating in SDS solution . The conformational change was confirmed by the abnormal profiles of Ferguson plots in gel electrophoretic analysis . It was concluded that conformational changes in the protein molecules are responsible for the heat modifiability of these proteins in SDS gel electrophoresis. J Cell Physiol, 1976 Dec, 89(4), 551 - 9 Nucleoside transport systems in Escherichia coli K12: specificity and regulation; Munch-Petersen A et al.; Two nucleoside transport systems have been verified and separated by mating and recombination experiments . The recipient strain was a mutant which is negative for transport of all nucleosides . The two systems differ in specificity and in regulation . One system transports pyrimidine and adenine nucleosides . It is regulated by the cytR gene . The other system transports all nucleosides and is regulated by the cytR as well as by the deoR genes . Enzyme assays performed on whole cells of strains, able or unable to transport nucleosides, indicate that the nucleoside catabolizing enzymes are located inside the permeability barrier of the cell. Curr Top Radiat Res Q, 1976 Dec, 11(3), 201 - 50 Irradiation of cells by single and double pulses of high intensity radiation: oxygen sensitization and diffusion kinetics; Epp ER et al.; The biological effects of ionizing radiation in living cells are the ultimate result of a long chain of events with the initial step being the local absorption of radiation . Whereas such physical abosrption is probably over within 10(-16) s after dose delivery, the biological consequences of radiation do not manifest themselves until very much later times . Between these two extremes of time, events occur relatively early at the molecular level which are undoubtedly critically related to the still unknown basic mechanisms of cellular radiation damage . These events may include not only the interaction of highly reactive species produced within the cell but also the diffusion of molecules such as oxygen or other chemical radiosensitizers. West Afr J Pharmacol Drug Res, 1976 Dec, 3(2), 153 - 60 Generic inequivalence between two brands of chloramphenicol capsule; Bugaje UM et al.; Generic inequivalence between two brands of chloramphenicol capsules has been investigated . Both brands complied with official standards for drug content and capsule disintegration time, and exhibited similar anti-bacterial activity when tested in vitro . A slow dissolution rate was observed with one brand which could be related to a formulation defect which might explain reported therapeutic inefficacy. Arch Biol Med Exp (Santiago), 1976 Dec, 10(1-3), 85 - 91 The stringent control mechanism . Binding of uncharged tRNA and stringent factor to Escherichia coli ribosomes; Richter D; The mechanism of the interaction of uncharged tRNA and stringent factor with the ribosomes during the in vitro synthesis of guanosine polypnophates (pppGpp and ppGpp) was studied . 70S ribosomes lacking proteins L7 and L12 were able to bind radioactive stringent factor but not EF-Tu or EF-G . In addition, ribosomes carrying EF-Tu, GMPPCP and Phe-tRNA bound as much stringent factor as 70S ribosomes alone . This evidence suggests that the stringent and elongation factors recognize nonidentical site (s) on the ribosomes . When a 70S - poly U - tRNA complex was formed in the absence of stringent factor and was subsequently incubated with Nac-Phe-tRNA or Phe-tRNA only the binding of Nac-Phe-tRNA to the complex was inhibited . However, when the 70S-poly U-tRNA complex was formed in the presence of stringent factor and then was incubated with Nac-Phe-tRNA or Phe-tRNA only the binding of Phe-tRNA was inhibited . These results indicate that the stringent factor directs uncharged codon-specific tRNA into the acceptor site of the ribosome. Zentralbl Bakteriol {Orig B}, 1976 Dec, 163(5-6), 509 - 23 {Kinetics of the release of testbacteria from the artificially contaminated hand (author's transl)}; Koller W et al.; It is demonstrated that the release of testbacteria from the finger tips of artificially contaminated hands is influenced to a very small degree only by application of the finger tip method when compared to the effect of ablutions . Therefore, without apprehension of influencing the post-values this method may be employed in order to assess pre-values as required by the test-model of Rotter and Mittermayer (5) for the evaluation of procedures for the hygienic disinfection of hands . In addition, it can be shown directly that it is irrelevant for the number of bacteria released after a germ-reducing procedure, whether the finger tip-method has been used or not, preceedingly . In contrast, all technical variations that aim at the restitution of the supposed loss of testbacteria (like renewed contamination after the assessment of prevalues) change the postvalues measurably and must be avoided, therefore . Drying of bacterial suspensions on the hands, as after artificial contamination, reduces the release of viable testbacteria depending on the time . This effect is stronger on the palms than on the finger tips . The influence of handbrushes on the release of testbacteria with simultaneous useage of detergents compares well with the effect of an alcohol disinfection . However, this method is not suitable to eliminate pathogens safely. J Biochem (Tokyo), 1976 Dec, 80(6), 1247 - 58 Nature of Escherichia coli mutants deficient in detergent-resistant and/or detergent-sensitive phospholipase A; Doi O et al.; 1 . Escherichia coli K-12 mutants deficient in detergent-resistant (DR) and detergent-sensitive (DS) phospholipases A and deficient in DS phospholipase A were isolated . 2 . The growth, compositions of phospholipids and fatty acids and turnover of phospholipids of three mutants (DR-, DS-, DR-DS-) were compared with those of their parent (DR- was isolated in a previous study) . 3 . Autodegradations of membrane phospholipids of 18,000 X g supernatants and precipitates of the homogenates of these three mutants were also compared with those of the parent, and the effects of various detergents and organic solvents on these activities were examined . 4 . We could not identify any significant physiological role for DR or DS phospholipase A. Can J Biochem, 1976 Dec, 54(12), 1061 - 8 Further studies on aspartate transcarbamoylase: molecular weight of the c3r6 complex and analysis of succinate inhibition in the native enzyme; Chan WW; The complex which is formed when excess regulatory subunits (r2) of aspartate transcarbamoylase (EC2.1.3.2) are added to a dilute solution of the catalytic subunit (c3) has been studied by gel-filtration on Sephadex G-200 . The elution volume indicates a Stokes' radius of between 5.42 and 5.92 nm, depending on the method of calculation . Using the sedimentation coefficient of 7.7S previously determined, the molecular weight is estimated to be close to 200 000, in support of the c3r6 structure proposed earlier for the complex . The calculated frictional coefficient indicates abnormal hydrodynamic properties which are probably due to unusual structure characteristics . The pattern of succinate inhibition of native aspartate transcarbamoylase has also been analyzed . At low concentrations, succinate activates the enzyme, presumably by converting it from the taut state to the relaxed (r) state . Further increase in the succinate concentration leads to competitive inhibition of the R state . Using a novel procedure for analysis of the data, the Michaelis constant for aspartate of the R state has been estimated to be about 7mM . This value is close to the Km of c3r6 for aspartate, measured under identical conditions . The result therefore provides further evidence suggesting that the c3r6 complex resembles the R state of the native enzyme. Biophys Chem, 1976 Dec, 6(1), 23 - 9 Dependence of the sedimentation of high molecular weight DNA on centrifuge speed; Hutchinson F et al.; A theory by Zimm {B.H.Zimm, Biophys . Chem . 1-(1974)279} predicts that for a given centrifuge speed, there is a broad maximum in a plot of the sedimentation coefficient of DNA against molecular wight . Experimental measurements of these maxima for various centrifuge speeds were made for double-helical DNA in neutral sucrose gradients and singlestrand DNA in alkaline gradients . The measurements are in quantitative agreement with the theory, providing good evidence for its validity . The existence of the maximum shows that there is a limit to the sedimentation rate under specified conditions for KNA in the linear form . By implication, DNA observed to sediment faster than this limit is not in the linear form to which most sedimentation theory is applicable. Mutat Res, 1976 Dec, 41(2-3), 185 - 200 Misrepair of overlapping daughter strand gaps as a possible mechanism for UV induced mutagenesis in UVR strains of Escherichia coli: a general model for induced mutagenesis by misrepair (SOS repair) of closely spaced DNA lesions; Sedgwick SG; It has been previously reported that an inducible form of post-replication repair appeared to be required for UV induced mutagenesis in a uvrA strain of Escherichia coli . It is shown here that the numbers of daughter strand gaps requiring inducible repair were similar to the numbers calculated to be overlapping one another in opposite daughter chromosomes . An estimation of survival with no repair of these gaps resembled the survival predicted with no mutagenesis . It is the thus proposed that inducible post-replication repair causes mutagenesis by the repair of overlapping daughter strand gaps . A general model for induced mutagenesis is presented . It is proposed that (a) some DNA lesions introduced by any DNA damaging agent may be close enough to interfere with constitutive repair replication of each other, (b) these lesions induce a repair system (SOS repair) which involves the recA+ lexA+ and polC+ genes (c) repair and concomitant mutagenesis occurs during repair replication by the insertion of mismatched bases opposite the noncoding DNA lesions. J Gen Microbiol, 1976 Dec, 97(2), 257 - 65 Growth on D-lyxose of a mutant strain of Escherichia coli K12 using a novel isomerase and enzymes related to D-xylase metabolism; Stevens FJ et al.; Escherichia coli K12 cannot grow on D-lyxose, but a mutant was isolated which can utilize D-lyxose as sole source of carbon and energy for growth . D-Lyxose is transported into the bacteria by the D-xylose permease . The mutant constitutively synthesizes a new isomerase which is not inducible in the parent strain under any of the conditions tested . This enzyme, whose native substrate appears to be D-mannose, fortuitously converts D-lyxose into D-xylulose . Its structural gene is located at around 85 min on the E . coli genetic map, away from other known isomerase genes . D-Xylulose is subsequently catabolized by the enzymes of the normal D-xylose metabolic pathway . D-Mannose isomerase was partially purified and some of its properties were examined. J Cell Physiol, 1976 Dec, 89(4), 545 - 9 Carbohydrate uptake by Escherichia coli; Kornberg HL; In contrast to active transport, the uptake of carbohydrates via the phosphoenolpyruvate-dependent phosphotransferase system (PTS) leads to the appearance in the cell of the sugar initially as a 1- or 6-phosphate ester . The components of the PTS that transfer phosphate to the sugar are not absolutely specific for any one sugar . Both their synthesis and their activity are controlled; in the latter, "fine" control, glucose-6-phosphate appears to play an important role . Studies of growth on, and uptake of, galactose by E.coli mutants devoid of components of the PTS and also devoid of active transport systems for galactose, suggest that proteins effecting facilitated diffusion of hexoses may be part of, or be closely associated with, the sugar-specific components of the PTS. J Cell Physiol, 1976 Dec, 89(4), 529 - 41 Cell envelope proteins involved in the transport of maltose and sn-glycerol-3-phosphate in Escherichia coli; Boos W; Two types of proteins are discussed in their role of facilitating the transport of maltose and sn-glycerol-3-phosphate in E . coli . The first protein is the receptor for phage lambda, known to be an outer membrane protein . By facilitating the diffusion of maltose and the higher maltodextrins through the outer membrane the effect of the lambda receptor is to decrease the Km of the transport system without influencing the Vmax of substrate flux . The second protein is a periplasmic protein that is induced by growth on glycerol and is essential for transport of sn-glycerol-3-phosphate in whole cells but not in membrane vesicles . This protein has solely been identified by the use of a two-dimensional polyacrylamide gel electrophoresis of periplasmic proteins in wild-type and mutants defective in sn-glycerol-3-phosphate transport. Eur J Biochem, 1976 Dec, 71(1), 201 - 10 Isolation and properties of an inhibitor of Escherichia coli RNA polymerase; Crimaldi A et al.; An inhibitor of the Escherichia coli RNA polymerase has been isolated from E . coli and has been partially characterized . The inhibitor, a polypeptide of molecular weight 70000, acts to shut off RNA synthesis at about the time that the first round of RNA synthesis is over, preventing any further RNA synthesis . The inhibitor apparently does not recognize specific termination sequences in the DNA template, since it works equally well with double-stranded DNA, single-stranded DNA and poly{d(A-T)} as templates for RNA synthesis, and because the RNA molecules synthesized from T7 DNA appear to be terminated at the same site either in the presence or absence of the inhibitor . Several experiments indirectly indicate that the inhibitor may reversibly bind to the RNA polymerase at the termination step, in a ratio of approximately one inhibitor molecule per polym