| the control of pyruvate kinases of escherichia coli. ii. effectors and regulatory properties of the enzyme activated by ribose 5-phosphate. | the pyruvate kinases of escherichia coli activated by ribose 5-phosphate (rp) has been partially purified. the active form of the enzyme has a molecular weight of about 180 000 as judged by sucrose density gradient centrifugations and sephadex g-150 chromatography. on dissociation in the absence of sulfhydryl reagents such as dithiothreitol, the enzyme is inactivated and it has a molecular weight of about 110 000. various substrates and effectors of the enzyme, with the exception of phosphate, d ... | 1975 | 236081 |
| in situ studies on the effect of acid extraction on the dna template activity of mature avian erythrocytes. | exogenous e. coli rna polymerase was used to determine the in situ dna template activity of ethanol/acetone fixed avian erythrocytes. no rna polymerase-catalyzed incorporation of 3h-utp was detected in mature avian erythrocytes while simultaneously fixed avian lymphocytes did exhibit incorporation of 3h-utp. nuclei of mature erythrocytes which were subjected to treatments known to remove histones showed dramatic increases in rna polymerase-catalyzed incorporation of 3h-utp. the chromatin of trea ... | 1975 | 236093 |
| infrared and raman spectra of phosphatidyl-ethanolamine and related compounds. | infrared and raman spectra of phosphatidylethanolamine from escherichia coli, l-alpha-glycero-phosphorylethanolamine and 0-phosphorylethanolamine were obtained. most of the bands were assigned to each vibrational mode based on the n deuteration effect, comparison of the intensity in the infrared and raman spectra and the depolarization degree measurement in the raman spectra. the spectra of phosphatidylethanolamine can be interpreted by assuming that the molecule takes the dipolar ionic structur ... | 1975 | 236097 |
| the threonine-sensitive homoserine dehydrogenase and aspartokinase activities of escherichia coli k12. specific inactivation of the homoserine dehydrogenase activity by the affinity label, 2-amino-4-oxo-5-chloropentanoic acid. | 2-amino-4-oxo-5-chloropentanoic acid inactivates specifically the homoserine dehydrogenase activity of the bifunctional enzyme, aspartokinase i--homoserine dehydrogenase i. the aspartokinase activity remains essentially untouched and retains its threonine sensitivity. the inactivation of the dehydrogenase requires the covalent binding of one equivalent of the analogue per subunit. alkylation does not affect the tetrameric state of the protein. the alkylating agent, a substrate analogue, meets th ... | 1975 | 236185 |
| thiolases of escherichia coli: purification and chain length specificities. | the presence of only one thiolase (ec 2.3.1.9) in wild-type escherichia coli induced for enzymes of beta oxidation was demonstrated. a different thiolase was shown to be present in a mutant constitutive for the enzymes of butyrate degradation. the two thiolases were purified to near homogeneity by a simple two-step procedure and were found to be associated with different proteins as shown by gel electrophoresis. the thiolase isolated from induced wild-type escherichia coli cell was active on bet ... | 1975 | 236278 |
| purification of thymidine phosphorylase from escherichia coli and its photoinactivation in the presence of thymine, thymidine, and some halogenated analogs. | isoelectric focusing was used as the final step in the isolation of thymidine phosphorylase which was found to have an isoelectric point of 4.1. analytical acrylamide gel electrophoresis showed the purified enzyme preparation contained one major protein band which stained for thymidine phosphorylase activity and usually a minor, faster migrating band devoid of activity. inactivation of thymidine phosphorylase alone or in the presence of sensitizers by ultraviolet light, primarily at 253.7 nm, fo ... | 1975 | 236298 |
| specific limited cleavage of bihelical deoxyribonucleic acid by wheat seedling nuclease. | wheat seedling nuclease catalyzes the hydrolysis of intact, bihelical viral dna or high molecular weight, native escherichia coli dna to produce limit polymers which are resistant to further hydrolysis by additional enzyme. these limit products are double-stranded polymers free of single strand interruptions and are terminated at their 5' ends with equal amounts of either deoxycytidylate or deoxyguanylate residues. the average size of the duplex limit products, as determined by (a) alkaline and ... | 1975 | 236302 |
| high resolution two-dimensional electrophoresis of proteins. | a technique has been developed for the separation of proteins by two-dimensional polyacrylamide gel electrophoresis. due to its resolution and sensitivity, this technique is a powerful tool for the analysis and detection of proteins from complex biological sources. proteins are separated according to isoelectric point by isoelectric focusing in the first dimension, and according to molecular weight by sodium dodecyl sulfate electrophoresis in the second dimension. since these two parameters are ... | 1975 | 236308 |
| a deoxyribonuclease of diplococcus pneumoniae specific for methylated dna. | a deoxyribonuclease specific for methylated dna was isolated from diplococcus pneumoniae. the enzyme, an endonuclease, degrades dna for escherichia coli to fragments of average molecular weight about half a million; it forms discrete fragments from phage lambda dna. methyl-deficient e. coli dna is not attacked, neither is dna from micrococcus radiodurans, which contains no methylated adenine or cytosine. nor is dna from d. pneumoniae or phage t7 attacked. however, dna from m. radiodurans, d. pne ... | 1975 | 236309 |
| multispecific aspartate and aromatic amino acid aminotransferases in escherichia coli. | two aminotransferases from escherichia coli were purified to homogeneity by the criterion of gel electrophoresis. the first (enzyme a) is active on l-aspartic acid, l-tyrosine, l-phenylalanine, and l-tryptophan; the second (enzyme b) is active on the aromatic amiono acids. enzyme a is identical in substrate specificity with transaminase a and is mainly an aspartate aminotransferase; enzyme b has never been described before and is an aromatic amino acid aminotransferase. the two enzymes are diffe ... | 1975 | 236311 |
| nationwide epidemic of septicemia caused by contaminated infusion products. iv. growth of microbial pathogens in fluids for intravenous infusions. | septicemia caused by contaminated infusion fluid is a newly appreciated hazard of intravenous infusion therapy. microorganisms of the tribe klebsielleae (klebsiella, enterobacter, and serratia) have predominated in these infections. members of this tribe found to possess a selecive ability over common non-klebsielleae microbial pathogens to proliferate rapidly in commerical parential fluids contaning clucose at room temperautre. fifty-one klebsielleae strains, washed twice before inoculation of ... | 1975 | 236343 |
| the opsonic fragment of the third component of human complement (c3). | human peripheral blood phagocytes ingest escherichia coli 026:b6 lipopolysaccharide (lps)-coated paraffin oil droplets containing oil red o only if fresh serum deposits c3 on the surfaces of the particles (opsonizes them), by reactions involving the properdin system. the rate of binding of purified [125-i]c3 in serum to lps-coated particles correlated precisely with the rate of acquisition of ingestibility assayed spectrophotometrically. once opsonized, lps-coated particles remained fully ingest ... | 1975 | 236357 |
| impedance monitoring of bacterial activity. | bacterial activity and growth were monitored by following the changes of electrical impedance of cultures in liquid media. the signal is expressed automatically as a curve similar to grwoth curves produced by other methods. the technique offers a new, rapid and sensitive means of detecting active micro-organisms and is potentially the basis of rapid automated systems in this field. the impedance changes indicate that the micro-organisms metabolise substrates of low conductivity into products of ... | 1975 | 236390 |
| l-glycerol-3-phosphate dehydrogenase from escherichia coli. | | 1975 | 236446 |
| l-ribulose-5-phosphate 4-epimerase from escherichia coli. | | 1975 | 236468 |
| n-acetylglucosamine-6-phosphate deacetylase and glucosamine-6-phosphate deaminase from escherichia coli. | | 1975 | 236479 |
| a new two-dimensional gel electrophoresis system for the analysis of complex protein mixtures: application to the ribosome of e. coli. | a new method for two-dimensional polyacrylamide gel electrophoresis of proteins is described. the method, illustrated here by its application for the analysis of ribosomal proteins of e. coli, has a high resolving power. the proteins s15 and s16 can be resolved either following alkylation or under reducing conditions. this was not possible with urea gel systems previously employed. the method should be advantageous in the identification of the components of dimers formed with the reagent methyl ... | 1975 | 236511 |
| transfer rna methyltransferases from yellow lupin seeds: purification and properties. | trna methyltransferases from extract of yellow lupin seeds were purified over 300-fold by the methods based on hydrophobic and affinity chromatography. however, in the most active fractions the methylating enzymes were over 2000 purified. the purified enzyme fractions catalysed the formation of 1-methyladenine and 5-methylcytosine using e. coli b and b. subtilis trnas as substrates and s-adenosylmethionine as the methyl donor. they were unable to methylate their own endogenous trna but they were ... | 1975 | 236549 |
| nad- and nadp-dependent 7alpha-hydroxysteroid dehydrogenases from bacteroides fragilis. | twenty strains of bacteroides fragilis were screened for hydroxysteroid oxidoreductase activity in cell-free preparations. eighteen strains were shown to contain nad-dependent 7alpha-hydroxysteroid dehydrogenase. sixteen of the strains containing the nad-dependent enzyme also contained nadp-depedent 7alpha-hydroxysteroid dehydrogenase, but invariably in lesser amounts. a strain particulary rich in both 7alpha-hydroxysteroid dehydrogenase activities was selected for further study. measurement of ... | 1975 | 236764 |
| kinetic studies of a beta-lactamase by a computerized microacidimetric method. | on-line computerized treatment of enzyme kinetic data allows the precise measurement of michaelis--menten constants (km and v) from a single progress curve. this method has been used to determine the kinetic constants of a beta-lactamase extracted from an escherichia coli strain. in the profile of enzymatic activity there obtained, km and v are a function of the ph. from these results some information is derived about the mechanism of the enzyme--substrate binding. | 1975 | 236772 |
| 19-f nmr studies of the binding of a fluorine-labeled phosphonate ion to e. coli alkaline phosphatase. | the interaction of a fluorinated phosphonate with zn-2+-and mn-2+-alkaline phosphatase as studied by 19-f nmr revealed a stoichiometry of 1:1 for the binding of the phosphonate anion to the enzyme. in the presence of two metal ions, one fluorinated phosphonate ion was found to interact strongly with the enzyme, while a different interaction was observed when the number of metal ions per enzyme exceeded two. phosphate replaced enzyme bound phosphonate, as is shown by the 19-f nmr spectra. no dire ... | 1975 | 236775 |
| [the effect of steroid hormones on beta-galactosidase activity in strains of e. coli k-12 with induced constitutional and super-repressed lac-operons]. | | 1975 | 236791 |
| the initiation of glycogen biosynthesis in escherichia coli. | | 1975 | 236916 |
| proceedings: a debranching enzyme in escherichia coli. | | 1975 | 236952 |
| reassembly of functionally active 50s ribosomal particles from proteins and rnas of escherichia coli. dependency of 50s ribosomal reassembly on 30s subunits. | further studies were made on the reassembly of 50s ribosomal subunits from proteins and rnas of e. coli. the reassembled particles had high activity in poly u-directed polyphenylalanine synthesis and their sucrose sedimentation properties were similar to those of the original intact particles. several factors affecting the reassembly were examined. the optimal ph for solubilization of ribosomal proteins was ph 9.5, and the optimal tris concentration was 0.75 to 1.00 m. in the reassembly mixture ... | 1975 | 237003 |
| phosphofructokinase from escherichia coli. | | 1975 | 237208 |
| radiation-induced dna strand breaks in e. coli measured within a fraction of a second. | | 1975 | 237238 |
| a rapid assay technique for rna ribose methylases. | a rapid technique for quantitative separation of ribose-methylated nucleosides from base-methylated and non-methylated nucleosides by chromatography on deae-cellulose paper in the presence of borate is described. the method has been used as an assay for trna ribose methylases from yeast, using under methylated escherichia coli trna as substrate. the main product formed with a partly purified yeast enzyme was characterized as 2'-o-methylcytidine. | 1975 | 237257 |
| inactivation of e. coli rna polymerase by pyridoxal 5'-phosphate: identificationof a low pka lysine as the modified residue. | | 1975 | 237508 |
| comparative study on conformational stability and subunit interactions of two bacterial asparaginases. | the denaturation and reconstitution of erwinia carotovora and escherichia coli l-asparaginases has been followed by optical rotatory dispersion, circular dichroism and analytical ultracentrifugation. denaturation in urea results in dissociation of the native enzyme (mol. wt. 140 000 approx.) to produce unfolded subunits (mol. wt. 35 000 approx.); the erwinia l-asparaginase subunits can be refolded by dilution or dialysis in alkaline conditions, ph 10.5, without aggregation to the active tetramer ... | 1975 | 237538 |
| the functional groups of the mg-ca atpase from escherichia coli. | the influence of hydrogen ion concentration on binding and conversion of mgatp and caatp by membrane bound and solubilized atpase from escherichia coli has been investigated. the reaction of enzyme (e), hydrogen ion (h+), and substrate (s) procedes according to the following scheme, where me is the metal ion and p is the product(s). (see article for formular). within experimental error, the results obtained with membrane-bound and solubilized atpase are identical. changing the concentration of m ... | 1975 | 237621 |
| wheat embryo ribonucleates. v. generation of n2--dimethylguanylate when 'fully sequenced' homogeneous species of transfer rna are used as substrates for wheat embryo methyltransferases. | when s-adenosly[methyl-14-c]methionine and various species of transfer rna are used as substrates for wheat embryo methyltransferases, the principal site of guanylate-n-2 methylation can be shown to be a g-residue between the stems of the dihydrouridine and anticodon loops. this common site of guanylate-n-2 methylation is referred to as the interstem target site. 2. when the interstem target site is the non-terminal g-residue in a g-c-g-c sequence, as in the cases of escherichia coli trna1-leu, ... | 1975 | 237622 |
| the radiometric assay of alkaline phosphatase activity with 125-i-labelled phenolphthalein monophosphate. | the coupling of 125-i to phenolphthalein monophosphate is described. hydrolytic cleavage of the phosphate group by alkaline phosphatases (ec 3.1.-3.1) releases labelled phenolphthalein which is extracted into ethyl acetate at ph 10. this forms the basis of a sensitive assay for the enzyme with the advantages of sensitivity and rapidity from the use of a gamma-emitter. results with escherichia coli and calf intestine alkaline phosphatases are presented. | 1975 | 237639 |
| threonine deaminase from escherichia coli. ii. maturation and physical properties of the enzyme from a mutant altered in its regulation of gene expression. | the biosynthetic l-threonine deaminase (l-threonine hydrolase deaminating, ec 4.2.1.16) has been purified from escherichia coli k12 regulatory mutant cu18. this mutant has properties that follow the predictions of the autogregulatory model previously proposed for the control of synthesis of the isoleucine-valine biosynthetic enzymes. the autoregulatory model specifies that l-threonine deaminase participates in the control of the expression of the ilv ade gene cluster as well as the ilv b gene an ... | 1975 | 237884 |
| nicotinamide adenine dinucleotide phosphate-malic enzyme of rat liver. purification, properties, and immunochemical studies. | rat liver malic enzyme (ec 1.1.1.40) was purified from livers of rats fasted and refed a high sucrose diet containing 1% desiccated thyroid powder. the purification was accomplished by a six-step procedure. the specific activity of the purified enzyme was increased 181-fold above that of the initial high speed supernatant of liver extracts. slight additional purification of malic enzyme was achieved with preparative disc electrophoresis. the specific activities of the purified rat liver malic en ... | 1975 | 237885 |
| effect of n-bromosuccinimide modification on dihydrofolate reductase from a methotrexate-resistant strain of escherichia coli. activity, spectrophotometric, fluorescence and circular dichroism studies. | when dihydrofolate reductase from a methotrexate-resistant strain of escherichia coli b, mb 1428, is treated with approximately a 5 mol ratio of n-bromosuccinimide (nbs) to enzyme at ph 7.2 and assayed at the same ph, there is a 40% loss of activity due to the modification of 1 histidine residue and possibly 1 methionine residue before oxidation of tryptophan occurs. the initial modification is accompanied by a shift of the ph for maximal enzymatic activity from ph 7.2 to ph 5.5 upon further tre ... | 1975 | 237891 |
| three photo-cross-linked complexes of yeast phenylalanine specific transfer ribonucleic acid with aminoacyl transfer ribonucleic acid synthetases. | yeast trna-phe has been cross-linked photochemically to three aminoacyl-trna synthetases, yeast phenylalanyl-trna synthetase, escherichia coli isoleucyl-trna synthetase, and e. coli valyl-trna synthetase. the two non-cognate enzymes are known to interact with trna-phe. in each complex, three regions on the trna are found to cross-link. two of these are common to all of the complexes, while the third is unique to each. thus, the cognate and non-cognate complexes bear considerable similarity to ea ... | 1975 | 237899 |
| glucose-sensitive adenylate cyclase in toluene-treated cells of escherichia coli b. | toluene treatment of escherichia coli b makes it possible to measure adenylate cyclase activity directly using [alpha-32-p]-atp as substrate. in contrast to french press extracts, the activity of adenylate cyclase in toluene-treated cells shows many of the characteristics of the enzyme seen in the intact cell. in both toluene-treated and intact cells the activity of adenylate cyclase is inhibited at least 85% by glucose, while in french press extracts the enzyme activity is much lower and is not ... | 1975 | 237907 |
| beta-ketoacyl-acyl carrier protein synthetase. characterization of the acyl-enzyme intermediate. | beta-ketoacyl-acyl carrier protein (acp) synthetase catalyzes the condensation reaction of fatty acid synthesis in escherichia coli. the homogeneous enzyme reacts with hexanoyl-coa to form hexanoyl-enzyme which was isolated and characterized. hexanoyl-enzyme contains 2 mol of hexanoate/mol of enzyme (molecular weight 66,000); it is liable at alkaline ph, and it reacts with neutral hydroxylamine to form hexanoyl hydroxamic acid. hexanoate was cleaved from the enzyme when hexanoyl-enzyme was subje ... | 1975 | 237913 |
| multiple forms of beta-ketoacyl-acyl carrier protein synthetase in escherichia coli. | two forms of beta-ketoacyl-acyl carrier protein (acp) synthetase (designated i and ii) have been identified in extracts of escherichia coli. synthetase i corresponds to the condensing enzyme that was studied earlier (greenspan, m.d., alberts, a.w., and vagelos, p.r. (1969) j. biol. chem. 244, 6477-6485); synthetase ii represents a new form of the enzyme. synthetase ii was isolated as a homogeneous protein. it differs from synthetase i in having a higher molecular weight (76,999 versus 66,000), a ... | 1975 | 237914 |
| inhibition of pathogenic enteric bacteria by hyperbaric oxygen: enhanced antibacterial activity in the absence of carbon dioxide. | the antibacterial effects of 24-h exposures to high-pressure oxygen in relation to environmental co(2) were studied at 3 atm absolute (ata) and at 1 ata. eight gram-negative, aerobic and facultatively aerobic, pathogenic enteric bacteria (salmonella typhosa, salmonella paratyphi, salmonella schottmuelleri, shigella dysenteriae, shigella flexneri, proteus vulgaris, pseudomonas aeruginosa, and escherichia coli) were exposed as shallow-broth cultures and agar surface cultures. although broths suppl ... | 1975 | 238466 |
| isolation of mutants of escherichia coli lacking nad- and nadp-linked malic. | | 1975 | 238534 |
| zinc and magnesium content of alkaline phosphatase from escherichia coli. | since alkaline phosphatase from escherichia coli was first reported to contain 2.1 g-atoms of zinc and 0.8 g-aton of magnesium per molecular weight 80,000 (plocke, d.j., levinthal, d., and vallee, b. l. (1962), biochemistry 1, 373-378), the procedures for isolation and purification of the enzyme, as well as values for the protein molecular weight, specific absorptivity, and maximal activity, have changed repeatedly. such variations have resulted in uncertainties concerning the molar metal conten ... | 1975 | 238559 |
| equilibrium measurements of cognate and noncognate interactions between aminoacyl transfer rna synthetases and transfer rna. | the interaction of escherichia coli isoleucyl-trna synthetase with its cognate and five noncognate trnas, and of yeast valyl-trna synthetase with its cognate and four noncognate trnas, has been measured directly by fluorescence quenching. the cognate associations are strongest (association constant of 10(8) m-1 or more at ph 5.5, 17 degrees). a wide variation is found in the strengths of the noncognate interactions; these have association constants smaller than that of these cognate association ... | 1975 | 238575 |
| specific conversion of s4 u to u in escherichia coli trna by iodate oxidation. | the minor nucleoside 4-thiouridine in escherichia coli trna is transformed selectively to uridine by iodate oxidation at acidic ph. the four major nucleotides were found to be inert under these conditions. the iodate oxidation appears to be more specific than the previous conversion methods reported, and has the advantage that it does not affect the chargeability of most trna. | 1975 | 238620 |
| histone-like protein in the prokaryote thermoplasma acidophilum. | the dna of the prokaryote thermoplasma acidophilum is associated with a histone-like protein that has the following properties: it has a high content (23%) of basic amino acids, is positively charged at neutral ph, is soluble in acid, and can stabilize dna against thermal denaturation. in polyacrylamide gel electrophoresis, in the presence of either sodium dodecylsulfate or urea, it migrates at the same rate as histone iv (f2a1) of calf thymus. the amino acid composition, however, it unusually r ... | 1975 | 238622 |
| glutathione biosynthesis in escherichia coli k 12. properties of the enzymes and regulation. | the synthesis of glutathione in escherichia coli k 12 was studied in crude, cell-free extracts. the ph optima and the apparent km values for the substrates have been determined for both synthesizing enzymes, gamma-glutamylcysteine synthetase and glutathione synthetase. gamma-glutamylcysteine synthetase was found to be approximately twice as active as glutathione synthetase. in a growing culture, the cellular level of gsh showed a considerable increase up to 6.6 mumol per ml cell pellet in the st ... | 1975 | 238647 |
| e. coli endotoxin shock in the cat; treatment with indomethacin. | 1. an earlier study had demonstrated that indomethacin, administered before e. coli endotoxin, abolished the initial pulmonary vasoconstriction and delayed the onset of the secondary shock phase that results from the intravenous injection of this agent in cats. the object of the present study was to determine whether indomethacin modified the shock phase when administered after endotoxin. 2. all the cats (whether or not they received indomethacin, 10 mg/kg) exhibited the characteristic features ... | 1975 | 238701 |
| some distinctive characteristics of the alkaline phosphatase of serratia marcescens. | a mutant strain of serratia marcescens produces a constitutive enzyme (phosphatase f), which differs from the alkaline phosphatase of escherichia coli in the following characteristics: one enzyme species with higher mobility on electrophoresis, less heat stability, no rapid reactivation following exposure to high hydrogen ion concentrations, no hybridization with e. coli enzyme in vitro, little activation at increased ionic strength, greater sensitivity to edta inhibition, and no cross reaction ... | 1975 | 238723 |
| [the effect of pyridoxal phosphate on the tryptophanases of five species of enterobacteriaceae]. | escherichia coli b and e. aurescens, shigella alkalescens, and proteus vulgaris et p. morganii tryptophanases (tpases) were studied for the spectral forms of the enzyme. the ph effect on the absorption spectrum and on the enzyme specific activity revealed that the coli group tpases are identical with but differ from proteus tpases which differ themselves. the coli group tpases attach 4 mol of pyridoxal phosphate (plp)/mol of enzyme, independently of the ph in the presence of k(plus) ions, and 9 ... | 1975 | 238730 |
| the active transport of carbohydrates by escherichia coli. | the active transport of carbohydrates by escherichia coli is discussed with particular reference to (1) identification of an uptake process as 'active transport', (2) nature and control of transport proteins, and (3) mechanisms of energy transduction. (1) the use of substrate analogues, of mutants blocked in metabolism and of subcellular vesicles in the isolation of the transport process from interference by subsequent metabolic reactions is described. criteria are outlined for establishing that ... | 1975 | 238808 |
| studies on the de novo biosynthesis of nad in escherichia coli. the separation of the nadb gene product from the nada gene product and its purification. | quinolinic acid (pyridine 2,3-dicarboxylic acid) which is an immediate precursor of the pyridine nucleotides, is synthesised from l-asparate and dihydroxyacetone phosphate in escherichia coli. extracts from certain nadb mutants complement the extracts prepared from all nada mutants for the enzymic synthesis of quinolinate. using the complementation assay, the quinolinate synthetase b protein has been purified more than 300-fold. the quinolinate synthetase b protein exists in all nada and nadc mu ... | 1975 | 238844 |
| antimicrobial properties of mannopeptins. | mannopeptins show in vitro antimicrobial activity against gram-positive and some gram-negative bacteria. the antimicrobial activity is unaffected by the addition of serum, and potentiated by alkaline ph or decrease in inoculum size. the antibiotics exert bectericidal effect at doses twice as high as the minimum inhibitory concentration. when the antibiotics were injected into mice through either intravenous, intraperitoneal, intramuscular or subcutaneous routes, the antimicrobial activity appear ... | 1975 | 238926 |
| regulation of glutamine transport in escherichia coli. | the formation of the high-affinity (km equal to 0.2 mum) l-glutamine transport system of escherichia coli strain 7 (lin) appears to be subject to the same major control as the glutamine synthetase (ec 6.3.1.2) of this gram-negative organism. culture of cells under nitrogen-limited conditions provides maximum derepression of both the glutamine synthetase and the glutamine transport system. nutritional conditions providing a rich supply of ammonium salts or available sources of nitrogen, i.e., con ... | 1975 | 238938 |
| transport of l-4-azaleucine in escherichia coli. | the uptake of l-4-azaleucine was examined in escherichia coli k-12 strains to determine the systems that serve for its accumulation. l-4=azaleucine in radio-labeled form was synthesized and resolved by the action of hog kidney n-acylamino-acid amidohydrolase (ec 3.5.1.b) on the racemic alpha-n-acetyl derivative of dl-[dimethyl-14c]4-azaleucine. l-4-azaleucine is taken up in e. coli by energy-dependent processes that are sensitive to changes in the ph and to inhibition by leucine and the aromatic ... | 1975 | 238951 |
| regulation of the lysine biosynthetic pathway in escherichia coli k-12: isolation of a cis-dominant constitutive mutant for ak iii synthesis. | a method for isolating regulatory mutants for the synthesis of lysine biosynthetic enzymes in escherichia coli is described. one of them is identified as a cis-dominant constitutive mutant for the synthesis of the lysine-sensitive asportokinase ak iii (lysc gene). | 1975 | 238953 |
| regulation of nitrogen metabolism in escherichia coli and klebsiella aerogenes: studies with the continuous-culture technique. | ammonia-nitrogen-limited continuous cultures of escherichia coli and klebsiella aerogenes contain induced levels of glutamine synthetase that is deadenylyated (i.e., fully active). in the presence of excess ammonia or glutamate in glucose-limited cultures of e. coli, glutamine synthetase is repressed and adenylylated (inactive). the average state of adenylylation (n) is a linear function of the specific growth rate. at low specific growth rates, glutamine synthetase is adenylylated; as the speci ... | 1975 | 238954 |
| purification and properties of malate dehydrogenase from pseudomonas testosteroni. | nicotinamide adenine dinucleotide-linked malate dehydrogenase has been purified from pseudomonas testosteroni (atcc 11996). the purification represents over 450-fold increase in specific activity. the amino acid composition of the enzyme was determined and found to be quite different from the composition of the malate dehydrogenases from animal sources as well as from escherichia coli. despite this difference, however, the data show that the enzymatic properties of the purified enzyme are remark ... | 1975 | 238957 |
| a transport system for phosphoenolpyruvate, 2-phosphoglycerate, and 3-phosphoglycerate in salmonella typhimurium. | salmonella typhimurium strain lt-2 was found to utilize phosphoenolpyruvate, 2-phosphoglycerate, and 3-phosphoglycerate as sole sources of carbon and energy for growth, but escherichia coli strains did not. the following evidence suggests that this growth difference was due to the presence in salmonella cells of an inducible phosphoglycerate permease distinct from previously studied transport systems: (a) the ability of cells to take up 3-phospho[14-c]glycerate was induced by growth in the prese ... | 1975 | 238977 |
| lysophospholipase of escherichia coli. | a lysophospholipase from escherichia coli cells was purified about 1,500-fold to near homogeneity by extraction with tris-hcl buffer, streptomycin treatment, (nh4)2so4 fractionation, column chromatographies on sephadex g-200, deae-cellulose and hydroxylapatite-cellulose, and polyacrylamide gel electrophoresis. the final preparation had a molecular weight of 39,500 plus or minus 500. the enzyme hydrolyzes 1-acylglycerylphosphorylethanolamine, 2-acylglycerylphosphorylethanoiamine, and 1-acylglycer ... | 1975 | 238979 |
| purification and properties of citrate lyase from streptococcus diacetilactis. | citrate lyase from streptococcus diacetilactis has been purified to yield a protein that was homogeneous as judged by sedimentation velocity and sedimentation equilibrium experiments. the enzyme's sedimentation coefficient is 16.8 s and its molecular weight is around 585,000. it contains three nonidentical subunits of about 53,000, 34,000, and 10,000 daltons. the enzyme in its active form contains an acetyl group which turns over during the citrate cleavage reaction. removal of the acetyl group ... | 1975 | 238987 |
| studies on indoleamine 2,3-dioxygenase. i. superoxide anion as substrate. | indoleamine 2,3-dioxygenase purified to apparent homogeneity from rabbit intestine was inhibited by scavengers for superoxide anion such as superoxide dismutase and 1,2-dihydroxybenzene-3,5-disulfonic acid (tiron). on the other hand, beta-carotene and 1,4-diazobicyclo-(2,2,2)-octane, scavengers for singlet oxygen, did not affect the enzyme activity significantly. the degree of inhibition of the dioxygenase by superoxide dismutase preparations from bovine erythrocytes, green peas, spinach leaves, ... | 1975 | 238993 |
| some factors influencing colicin activity between pathogenic and commensal escherichia coli from the pig. | commensal strains of escherichia coli derived from pigs had a broad spectrum of in vitro colicin acitivity against pathogenic serotypes. of eight pathogenic serotypes tested, only three were colicinogenic and were active against relatively few commensal strains. colicin activity was influenced by temperature, ph and oxygen tension as well as by the availability of certain nutrients and the presence of trypsin. lack of colicin activity in intestinal supernatant fluid was ascribed to the concentra ... | 1975 | 239446 |
| in vivo and in vitro phosphorylation of dna-binding proteins from escherichia coli. | a deoxyribonucleoprotein (dnp) complex has been isolated from escherichia coli cells by chromatography on sephadex g-200. the dnp complex contains phosphoproteins and the content of phosphorus bound to the dnp protein is 3 times higher than in cytoplasmic proteins not bound to dna. these results have been confirmed by in vivo (32-p-kh2po4) and in vitro (32-p-atp) phosphorylation of e. coli dna-binding proteins isolated by chromatography on dna--cellulose. | 1975 | 239529 |
| an inducible beta-lactamase in a strain of escherichia coli. | the production of beta-lactamase (penicillin/cephalosporin beta-lactam amidohydrolase, e.c.3.5.2.6) was found to be inducible in a clinically isolated strain of escherichia coli. this is the first report of an inducible beta-lactamase in e. coli. the optimal concentration of inducer was 400 mug/ml of ml of benzylpenicillin, or 800 mug/ml of 6-aminopenicillanic acid. about fiftyfold induction was achieved. maximum induction took ninety minutes from the time of adding the inducer. induction was ab ... | 1975 | 239625 |
| affinity labeling of the ribonucleic acid component adjacent to the peptidyl recognition center of peptidyl transferase in escherichia coli ribosomes. | n-iodacetylphenylalanyl-trna was used as an affinity label for localizing the rna components intimately related to the peptidyl transferase activity of escherichia coli ribosomesmthis analogue could specifically alkylate a unique nucleotide chain of 23-s rna. the alkylation was strongly enhanced by poly(u), and was dependent on the presence of both 50- and 30-s subunits; chloramphenicol inhibited the reaction, wheras blasticidin s stimulated it. the alkylated rna base was found to be adenine. th ... | 1975 | 239742 |
| atpase and gtpase activities associated with the 5-s rna-protein complex of escherichia coli ribosomes. | specific 5-s rna-protein complexes were reconstituted from escherichia coli 5-s rna and 50-s ribosomal proteins. these complexes consist of 5-s rna and two major proteins, namely e-l18 and e-l25. analysis for enzymatic activities shows that atp and gtp are hydrolyzed and that this hydrolysis is independent of elongation factors. | 1975 | 239743 |
| derepressed levels of glutamate synthase and glutamine synthetase in escherichia coli mutants altered in glutamyl-transfer ribonucleic acid synthetase. | the levels of glutamate synthase and of glutamine synthetase are both derepressed 10-fold in strain jp1449 of escherichia coli carrying a thermosensitive mutation in the glutamyl-transfer ribonucleic acid (trna) synthetase and growing exponentially but at a reduced rate at a partially restrictive temperature, compared with the levels in strain ab347 isogenic with strain jp1449 except for this thermosensitive mutation and the marker aro. these two enzymes catalyze one of the two pathways for glut ... | 1975 | 239924 |
| l-asparagine uptake in escherichia coli. | the uptake of l-asparagine by escherichia coli k-12 is characterized by two kinetic components with apparent km values of 3.5 mum and 80 mum. the 3.5 mum km system displays a maximum velocity of 1.1 nmol/min per mg of protein, which is a low value when compared with derepressed levels of other amino acid transport systems but is relatively specific for l-asparagine. compounds providing effective competition for l-asparagine uptake were 4-carbon analogues of the l-isomer with alterations at the b ... | 1975 | 239925 |
| regulation of glutaminase levels in escherichia coli. | nitrogenous metabolites, cyclic adenosine 3':5'-monophosphate (camp), and the stage of culture growth all influence the levels of glutaminase a in escherichia coli, but no variables in culture conditions alter the levels of glutaminase b. growth of e. coli on culture media containing glucose and excess ammonia results in a rise in the level of glutaminase a as the cultures enter stationary phase; this rise is abolished by ammonia limitation. camp or glycerol reduce the level of glutaminase a. in ... | 1975 | 239927 |
| guanylate cyclase in escherichia coli. purification and properties. | guanylate cyclase has been purified from extracts of escherichia coli. after a 1000-fold purification, the enzyme contains only minor contaminants as judged by disc gel electrophoresis. the km for gtp is approximately 7 times 10(-5) m and the optimal ph is 8.0. more activity is observed with mn2+ than with mg2+, and maximal activity is observed at 0.14 mm mn2+ and 1.4 mm mg2+. based on its behavior on sephadex g-100, the molecular weight of e. coli guanylate cyclase is about 30,000. disc gel ele ... | 1975 | 239941 |
| cascade control of escherichia coli glutamine synthetase. properties of the pii regulatory protein and the uridylyltransferase-uridylyl-removing enzyme. | the pii regulatory protein of escherichia coli glutamine synthetase exists in two interconvertible forms: a uridylylated form (piid) which promotes the deadenylylation of glutamine synthetase and an unmodified form (piia) which promotes the adenylylation of glutamine synthetase (mangum, j.h., magni, g., and stadtman, e.r. (1973) arch. biochem. biophys. 158, 514-525). pii has been purified to homogeneity. its molecular weight is 44,000. the protein is composed of four subunits, each with a molecu ... | 1975 | 239942 |
| isolation and characterization of jack bean beta-galactosidase. | a simple procedure has been devised to isolate beta-galactosidase from jack bean meal. the final preparation gives one major protein banc in disc gel electrophoresis. the substrate specificity of this enzyme toward some natural oligosaccharides, glycoproteins, and sphingoglycolipids has been examined in detail. among three isomers of n-acetyllactosamine, galbeta1leads to4glcnac; while galbeta1leads to3glcnac was hydrolyzed very slowly. this property can be used to distinguish the galactose linka ... | 1975 | 239949 |
| pyridoxal 5'-phosphate, a fluorescent probe in the active site of aspartate transcarbamylase. | pyridoxal-p reacts specifically with a single lysine residue at the active site of escherichia coli aspartate transcarbamylase (greenwell, p., jewett, s. l., and stark, g. r. (1973) j. biol. chem. 248, 5994-6001). reduction of the schiff base with sodium borohydride, succinylation of the remaining lysine residues, and digestion with trypsin result in formation of a single pyridoxyl peptide, which was purified to homogeneity after chromatography on deae-cellulose, treatment with alkaline phosphat ... | 1975 | 239951 |
| enterotoxigenic intestinal bacteria in tropical sprue. iii. preliminary characterization of klebsiella pneumoniae enterotoxin. | cell-free broth filtrates of a strain of klebsiella pneumoniae serotype 5 retained their capacity to induce fluid secretion in the rabbit ileal loop model after heating (100 c for 30 min), acid treatment (ph 4.4), and dialysis through viscose tubing. sequential passage of an acetone precipitate of the broth filtrate through diaflo membranes yielded an active fraction in the um 2, but not the um 10, retentate; this observation indicates that the molecular weight of the enterotoxin is in the range ... | 1975 | 239990 |
| studies of introital colonization in women with recurrent urinary infections. i. the role of vaginal ph. | the ph of the vaginal introitus was compared to quantitative cultures of the introital mucosa (escherichia coli, proteus mirabilis and streptococcus faecalis) in 800 samples. introital carriage of more than 100 bacteria per ml. was significantly greater at ph of more than 4.4 (p less than 0.005) when compared to mucosal ph of less than or equal to 4.4. | 1975 | 240038 |
| studies of introital colonization in women with recurrent urinary infections. ii. a comparison of growth in normal vaginal fluid of common versus uncommon serogroups of escherichia coli. | vaginal fluid collected from volunteers who denied a history of urinary infections was bactericidal to escherichia coli at ph 4.0. when the ph was increased to 6.5 with sodium hydroxide, the same vaginal fluids supported bacterial growth. if vaginal fluid was adjusted at ph increments between 4.0 and 5.0, and inoculated with common and uncommon serogroups of escherichia coli, the uncommon o-groups that never cause urinary infections were significantly (p less than 0.005) more inhibited by the lo ... | 1975 | 240039 |
| [comparison of the antibacterial activity of amikacin (bb-k8) with other aminoglycosides against pathogens recently isolated from clinical materials (author's transl) ]. | we determined the antibacterial activity of amikacin against 1,277 strains of pathogenic bacteria isolated from clinical materials during 1974, including beta hemolytic streptococci, pneumococci, enterococci, staphylococcus aureus, staph. epidermidis, escherichia coli, klebsiella, enterobacter, citrobacter, serratia, proteus morganii and pseudomonas aeruginosa, and compared the minimum inhibitory concentration (mic) of this drug with gentamicin, dibekacin, tobramycin and kanamycin. 1)antibacteri ... | 1975 | 240047 |
| [chemotherapy of purulent meningitis in children (author's transl)]. | purulent meningitis in patients admitted to the pediatric department of kyoto university hospital and affiliated institutions from 1951 through 1973 were studied with emphasis on the kinds of the causative organisms and the susceptibility of these organisms to antibiotics. the findings in this study have served to help select antibiotics most likely to be effective against this disease. the overall incidence of purulent meningitis was 0.68%. this figure decreased little throughout the period. as ... | 1975 | 240048 |
| purification and characterization of a streptomyces albus endo-n-acetylmuramidase lytic for group a and other beta haemolytic streptococci. | the purification and characterization of the streptolytic exo-enzyme from the maxted-mccarty strain of streptomyces albus is described. this enzyme was shown to be an endo-n-acetylmuramidase with a molecular weight of 10 to 12,000 and optimal activity at ph 8 and 45 degrees c. the enzyme is lytic for streptococci of various groups, micrococcus lysodeikticus, staphylococcus aureus, as well as escherichia coli. it closely resembles the f1 endo-n-acetylmuramidase described by ghuysen et al. (1966) ... | 1975 | 240102 |
| a tw0-component ribonucleotidyl transferase from e. coli. | some properties of an enzyme designated as a two component ribonucleotidyl transferase from e. coli are presented. the enzyme in the presence of magnesium ions catalyzes the synthesis of polyribonucleotide chains using all four nucleoside triphosphates as substrates. the enzyme consists of two components; component a in the presence of mg2+ catalyzes the synthesis of homo- and heteropolymers using atp, ctp and utp but not gtp as substrates. component b itself does not catalyze any synthesis at a ... | 1975 | 240121 |
| [investigations of the influence of ph on the oxidative degradation of glucose by e. coli (biochemical glucose demand) (author's transl)]. | the oxidative degradation of glucose by e. coli was studied in the warburg manometer. the ph of the medium was established in these studies at values between 5.5 and 8.0. analysis of the reaction kinetics by plotting time/consumption curves shows that three consecutive reactions can be distinguished as the substrate is eliminated from the medium: an adaptation phase which is generally relatively brief is followed by two reactions, of which the first proceeds more rapidly or more slowly than reac ... | 1975 | 240243 |
| chemostat culture of escherichia coli k-12 limited by the activity of alkaline phosphatase. | the growth-limiting reaction of a chemostat culture of escherichia coli k-12 was the hydrolysis of beta-glycerophosphate by alkaline phosphatase. the culture was buffered at ph 5.2 where alkaline phosphatase was unable to supply phosphate to the cell at a rate sufficient to sustain the maximum rate of growth. alkaline phosphatase activity in this system is discussed in terms of the so-called flip-flop mechanism. | 1975 | 240310 |
| phospholipid requirements of atpase of escherichia coli. | | 1975 | 240320 |
| biodegradative ornithine decarboxylase of escherichia coli. purification, properties, and pyridoxal 5'-phosphate binding site. | the biodegradative ornithine decarboxylase of escherichia coli has been purified to apparent homogeneity. at its ph optimum (ph 7.0), the enzyme exists as a dimer of 160,000 molecular weight. aggregation of the dimer was promoted by lower ph values. the enzyme requires pyridoxal 5'-phosphate for activity. the coenzyme appears to be bound in schiff base linkage as suggested by spectral studies and inhibition by nabh4. the following sequence was determined for the coenzyme binding site: val-his-(e ... | 1975 | 240388 |
| reversible reaction of cyanate with a reactive sulfhydryl group at the glutamine binding site of carbamyl phosphate synthetase. | carbamyl phosphate synthetase from escherichia coli reacts stoichiometrically (one to one) with [14c]cyanate to give a 14c-labeled complex which can be isolated by gel filtration. the formation of the complex is prevented if l-glutamine is present or if the enzyme is first reacted with 2-amino-4-oxo-5-chloropentanoic acid, a chloro ketone analog of glutamine which has been shown to react with a specific sh group in the glutamine binding site. the rate of complex formation is increased by adp and ... | 1975 | 240389 |
| studies of homogeneous "biosynthetic" l-threonine dehydratase from escherichia coli k-12. some kinetic properties and molecular multiplicity. | "biosynthetic" l-threonine dehydratase (ec 4.2.1.16) was purified to a homogeneous state with 29% yield of total activity from escherichia coli k-12. the homogeneity of the enzyme was shown by polyacrylamide gel disc electrophoresis in the presence of dodecyl sulphate. the enzyme consisted of equal subunits having a molecular weight of about 57 000. the polyacrylamide gel disc electrophoresis has shown that the native enzyme consisted of a set of oligomeric forms. the multiplicity of molecular o ... | 1975 | 240428 |
| studies on aspartase. ii. role of sulfhydryl groups in aspartase from escherichia coli. | aspartase (l-aspartate ammonia-lyase, ec 4.3.1.1) of escherichia coli w contains 38 half-cystine residues per tetrameric enzyme molecule. two sulfhydryl groups were modified with n-ethylmaleimide or 5,5'-dithiobis(2-nitrobenzoic acid) (dtnb) per subunit, while 8.3 sulfhydryl groups were titrated with p-mercuribenzoic acid. in the presence of 4 m guanidine - hcl, 8.6 sulfhydryl groups reacted with dtnb per subunit. aspartase was inactivated by various sulfhydryl reagents following pseudo-first-or ... | 1975 | 240429 |
| circular dichroism studies of dihydrofolate reductase from a methotrexate-resistant strain of escherichia coli b, mb 1428: ternary complexes. | circular dichroism has been used to monitor the binding of pyridine nucleotide cofactors to enzyme-folate analog complexes of dihydrofolate reductase from escherichia coli b (mb 1428). the enzyme binds one molar equivalent of many folate analogs and two molar equivalents of several pyridine nucleotide cofactors. the apo-enzyme has very low optical activity. the binding of folate analogs including folate, dihydrofolate, methotrexate, trimethoprim and pyrimethamine induce large cotton effects. pyr ... | 1975 | 240430 |
| isolation and properties of escherichia coli atpase mutants with altered divalent metal specificity for atp hydrolysis. | a method was devised for isolation of large numbers of energy-transducing atpase (coupling factor) mutants based on a modification of the procedure of hong and ames (hong, j. and ames, b. n. (1971) proc. natl. acad. sci. u.s. 68, 3158-3162) for localized mutagenesis of any small region of the bacterial chromosome using transducing phages. the principle of this procedure is to mutate p1-transducing phage particles carrying the atpase genes (unc (uncoupled) dna) using the strong chemical mutagen h ... | 1975 | 240443 |
| ribonucleotide reductase from escherichia coli: demonstration of a highly active form of the enzyme. | ribonucleotide reductase from escherichia coli consists of two nonidentical subunits, proteins b1 and b2. the activity of the enzyme in crude extracts prepared from mechanically disrupted bacteria is very low. enzyme activity is stimulated 5 to 10-fold by addition of an excess of either subunit. concentrated extracts from cells lysed gently on cellophane discs (schaller et al.) contained 10 to 20-fold higher activity than extracts from mechanically disrupted cells. this activity was not further ... | 1975 | 240707 |
| conversion of escherichia coli cell-produced metabolic energy into electric form. | the formation of membrane potential in energized e. coli cells has been investigated by means of ionic penetrants. the fluxes of anions and cations in opposite directions have been observed: anions moved out and cations moved into the cells. the energy-linked uptake of cations was stoichiometrically coupled with the outflow of h+ ions from the cells. the value of a membrane potential in the energized cells calculated from a distribution of permanent cations was in the range of -140 mv (inside mi ... | 1975 | 240812 |
| mutants of escherichia coli defective in membrane phospholipid synthesis. properties of wild type and km defective sn-glycerol-3-phosphate acyltransferase activities. | the sn-glycerol-3-phosphate (glycerol-p) acyltransferase, the first enzyme of membrane phospholipid synthesis in escherichia coli, was investigated in a wild type and a mutant strain defective in this activity. the mutant strain, selected as a glycerol-p auxotroph, was previously shown to contain a glycerol-p acyltransferase activity with an apparent km for glycerol-p 10 times higher than that of its parent or revertants. the membranous mutant glycerol-p acyltransferase but did not appear to be ... | 1975 | 240816 |
| mutants of escherichia coli defective in membrane phospholipid synthesis. phenotypic suppression of sn-glycerol-3-phosphate acyltransferase km mutants by loss of feedback inhibition of the biosynthetic sn-glycerol-3-phosphate dehydrogenase. | revertants of escherichia coli mutants defective in the first enzyme of membrane phospholipid synthesis, sn-glycerol-3-phosphate (glycerol-p) acyltransferase, were investigated. these glycerol-p acyltransferase mutants, selected as glycerol-p auxotrophs, contained membranous glycerol-p acyltransferase activity with an apparent km for glycerol-p 10 times higher than the parental activity. the glycerol-p acyltransferase activity was also more thermolabile in vitro than the parental activity. most ... | 1975 | 240817 |
| a novel oligoribonuclease of escherichia coli. i. isolation and properties. | a new ribonuclease has been isolated from escherichia coli. the enzyme is present in the 100,000 times g supernatant fraction and has been purified over 200-fold. studies of the enzyme reveal that: 1. the enzyme shows a marked preference for oligoribonucleotides; indeed, the reaction rate is inversely proportional to the chain length of the substrate. the enzyme does not attack polynucleotides even at high concentrations of enzyme and has no detectable dnase activity. 2. the enzyme is stimulated ... | 1975 | 240824 |
| biosynthesis of bacterial glycogen. kinetic studies of a glucose-1-phosphate adenylyltransferase (ec 2.7.7.27) from a glycogen-deficient mutant of escherichia coli b. | an escherichia coli b mutant, sg14, accumulates glycogen at 28% the rate observed for the parent e. coli b strain. the glycogen accumulated in the mutant is similar to the glycogen isolated from the parent strain with respect to alpha- and beta-amylosis, chain length determination, and i2-complex absorption spectra. the sg14 mutant contains normal glycogen synthase and branching enzyme activity but has an adp-glucose pyrophosphorylase with altered kinetic and allosteric properties. the mutant en ... | 1975 | 240834 |
| characterization of an active transport system for calcium in inverted membrane vesicles of escherichia coli. | the energy-dependent uptake of calcium by inverted membrane vesicles of escherichia coli was investigated. methods for preparation and storage of the vesicles were devised to allow for the maximal activity and stability of the calcium transport system. the ph and temperature optima for the reaction were observed to occur at ph 8.0 and 30 degrees, respectively. the eft was found that the extent of the reaction depended on the presence of phosphate or oxalate. phosphate was found to enter the vesi ... | 1975 | 240836 |
| protease ii from escherichia coli. purification and characterization. | we have previously demonstrated the existence of two types of endopeptidase in escherichia coli. a purification procedure is described for one of these, designated protease ii. it has been purified about 13,500-fold with a recovery of 24%. the isolated enzyme appears homogeneous by electrophoresis and gel filtration. its molecular weight is estimated by three different methods to be about 58,000. its optimal ph is around 8. protease ii activity is unaffected by chelating agents and sulfhydryl re ... | 1975 | 240839 |
| functional arginyl residues as atp binding sites of glutamine synthetase and carbamyl phosphate synthetase. | the reaction of phenylglyoxal with two enzymes in which atp plays a complex role has been studied. both ovine brain glutamine synthetase and escherichia coli carbamyl phosphate synthetase [carbamoyl-phosphate synthase (glutamine); atp:carbamate phosphotransferase (dephosphorylating, amido-transferring); ec 2.7.2.9]were inactivated by phenylglyoxal. the specificity of this reagent for arginyl residues of the two proteins was confirmed by amino acid analysis. atp, but not the other substrates, pro ... | 1975 | 241076 |
| [toxin production by enteropathogenic colibacilli in adult persons (author's transl)]. | culture filtrates of enteropathogenic strains of e. coli from adult patients with cholera-like diarrhoea produced a rhythm-disturbing effect when injected into isolated sacklets of rabbit ileum. this action was shown to be medium-dependant. it could not be elicited by cultures grown in synthetic medium. meat extract cultures gave variable results, but the gut movements could be irritated regularly when cultures were grown in a casamino acids - yeast extract medium (table, figure). this activity ... | 1975 | 241179 |