| interactions of guanidinium chloride and pyridine nucleotides with oxidized and two-electron-reduced lipoamide dehydrogenase from escherichia coli. | | 1979 | 33178 |
| the stimulation of escherichia coli aspartate transcarbamylase activity by adenosine triphosphate. relation with the other regulatory conformational changes; a model. | | 1978 | 33272 |
| iron, an essential element for biosynthesis of aromatic compounds. | homogeneous preparations of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase [7-phospho-2-keto-3-deoxy-d-arabino-heptonate d-erythrose-4-phosphate lyase (pyruvate phosphorylating), ec 4.1.2.15] isolated as the enzyme-phosphoenolpyruvate complex from escherichia coli are shown by atomic absorption analysis to contain approximately one mole of iron per mole of native enzyme. no cobalt was found, in contrast to suggestions of earlier workers. pure enzyme preparations show a unique absorption ma ... | 1978 | 33383 |
| chemical modification of the surfaces of bacterial cell walls. | the surfaces of the isolated cell walls of four bacterial species were studied by microelectrophoresis following chemical treatments intended to remove specific charged groups. acid-base titrations of the walls were used to assess specificity and extent of the modifications. carboxyl groups were specifically and completely modified by activation with a water-soluble carbodiimide and subsequent reaction with a nucleophile, such as glycinamide, to give an uncharged ph-stable product. aqueous media ... | 1978 | 33400 |
| polyglycolic acid (dexon) sutures in escherichia coli infected urine. | the tensile strength, knot strength and stretch of polyglycolic acid (dexon) was studied after emersion in physiological saline, sterile urine and infected urine. tests were made each day under controlled conditions over a 10 day period. the results are compared with those of other earlier studies. tensile strength, knot strength and stretch were found to be fully acceptable in all studies, and there are no grounds to advise against the use of dexon when urine is infected. | 1979 | 33447 |
| cascade control of e. coli glutamine synthetase. i. studies on the uridylyl transferase and uridylyl removing enzyme(s) from e. coli. | | 1978 | 33596 |
| cascade control of e. coli glutamine synthetase. ii. metabolite regulation of the enzymes in the cascade. | | 1978 | 33597 |
| microbial metabolism of amino alcohols. purification and properties of coenzyme b12-dependent ethanolamine ammonia-lyase of escherichia coli. | 1. the 120-fold purification of ethanolamine ammonia-lyase from escherichia coli extracts, to apparent homogeneity, is described. ethanolamine, dithiothreitol, glycerol and kcl protected the apoenzyme from inactivation. 2. at the optimum ph7.5, k(m) values for ethanolamine and coenzyme b(12) were 44mum and 0.42mum respectively. the k(m) for ethanolamine was markedly affected by ph, transitions occurring at ph7.0 and 8.35. 3. the enzyme was specific for ethanolamine as substrate, none of the 18 a ... | 1978 | 33657 |
| l-threonine dehydrogenase of escherichia coli k-12. | | 1978 | 33672 |
| proton electrochemical gradient in escherichia coli cells and its relation to active transport of lactose. | | 1979 | 33700 |
| laboratory studies with bl-s 578 (cefadroxil) a new broad-spectrum orally active cephalosporin. | bl-s 578 (cefadroxil) is a new orally active semisynthetic cephalosporin antibiotic with broad-spectrum antibacterial activity. the new compound was evaluated in vitro in comparison with cephalexin. some properties studies such as, antibacterial activity, binding with serum proteins and stability in acid and neutral solution at 37 degrees c for both cephalosporins were similar. in experimental infections of mice, the protective action of bl-s 578 was more effective than cephalexin against staphy ... | 1979 | 33784 |
| topography of nitrate reductase of the cytoplasmic membrane of escherichia coli: the nitrate-reducing site [proceedings]. | | 1978 | 33859 |
| nutritional requirements for synthesis of heat-labile enterotoxin by enterotoxigenic strains of escherichia coli. | optimal growth conditions have been established for production of heat-labile enterotoxin (lt) by both porcine and human strains of enterotoxigenic (ent(+)) escherichia coli. there were no unusual growth factor requirements, and some strains produced fairly high levels of lt in a basal salts medium containing 0.5% glucose if the ph was carefully controlled. several amino acids markedly stimulated lt synthesis when added to the basal salts-glucose medium. methionine and lysine were the most stimu ... | 1979 | 33900 |
| glutamine synthetase regulation, adenylylation state, and strain specificity analyzed by polyacrylamide gel electrophoresis. | we used polyacrylamide gel electrophoresis to examine the regulation and adenylylation states of glutamine synthetases (gss) from escherichia coli (gs(e)) and klebsiella aerogenes (gs(k)). in gels containing sodium dodecyl sulfate (sds), we found that gs(k) had a mobility which differed significantly from that of gs(e). in addition, for both gs(k) and gs(e), adenylylated subunits (gs(k)-adenosine 5'-monophosphate [amp] and gs(e)-amp) had lesser mobilities in sds gels than did the corresponding n ... | 1979 | 33958 |
| dihydrofolate reductase from trimethoprim-resistant escherichia coli mb 3746 and mb 3747. purification, amino acid composition, and some kinetic properties. | | 1979 | 33983 |
| inactivation of escherichia coli elongation factor ts by the arginine-specific reagent butanedione. | | 1979 | 33984 |
| agrobactin, a siderophore from agrobacterium tumefaciens. | a siderophore (microbial iron transport compound) was isolated from low iron cultures of agrobacterium tumefaciens b6. the substance was characterized as a threonyl peptide of spermidine acylated with 3 residues of 2,3-dihydroxybenzoic acid, the carbonyl group of 1 residue of the latter participating in an oxazoline ring with the beta-hydroxyl of the threonine moiety. the compound, n-[3-(2,3-dihydroxybenzamido)propyl]-n-[4-(2,3-dihydroxybenzamido)butyl]-2-(2,3-dihydroxyphenyl)-trans-5-methyl-oxa ... | 1979 | 33987 |
| cation/proton antiport systems in escherichia coli. properties of the calcium/proton antiporter. | | 1979 | 33991 |
| site-exposure model for proton-lactose symport in escherichia coli. | | 1978 | 34066 |
| fluroxene mutagenicity. | the commercially available volatile anesthetic fluroxene (2,2,2-trifluoroethyl vinyl ether) which contains the stabilizer n-phenyl-1-napthylamine, was tested for mutagenicity using four strains of s. typhimurium, ta1535, ta1537, ta98 and ta100, and one strain of e. coli, wp2. in addition, purified fluroxene; n-phenyl-1-napthylamine; trifluoroethanol, a major metabolite of fluoroxene; and urine from rats anesthetized with fluroxene were tested. several procedures were utilized including exposure ... | 1978 | 34096 |
| phosphorylation of isocitrate dehydrogenase of escherichia coli. | addition of acetate to a stationary phase culture of escherichia coli in glycerol mineral salts medium containing phosphorus-32-labeled orthophosphate results in rapid loss of isocitrate dehydrogenase activity and concomitant incorporation of phosphorus-32 into the enzyme. this is the first example of protein phosphorylation in a bacterium in which the endogenous substrate for the protein kinase has been identified. | 1979 | 34215 |
| enumeration of stressed cells of escherichia coli. | cells of escherichia coli k-12 were stressed by heating at 48 degrees c or by acid treatment at ph 4.2 for periods up to 1h. the addition of catalase to the selective medium increased the count of heat-stressed cells by 2.3-fold and acid-stressed cells by 4.8-fold. however, these values represented only a small percentage (3% for heat-stressed and 6% for acid-stressed cells respectively) of the population of injured but still viable cells. the addition of mannitol to the selective medium used to ... | 1979 | 34476 |
| atp synthesis driven by a ph gradient imposed across the cell membranes of lipoic acid and unsaturated fatty acid auxotrophs of escherichia coli. | | 1979 | 34529 |
| stimulation of beta-lactamase activity in escherichia coli. | | 1978 | 34564 |
| attachment of bacteria to exfoliated cells from the urogenital tract. | to establish urogenital infections, organisms must adhere to the mucosal lining. a differential adherence capacity among various bacterial species was observed when exfoliated urethral and urothelial cells were tested in an in vitro system. no difference in the adherence capacity of a particular species was observed when tested with exfoliated cells obtained from voided urine from different healthy individuals of the same sex. escherichia coli harvested directly from urine specimens of patients ... | 1979 | 34577 |
| some properties of escherichia coli glutamine synthetase after limited proteolysis by subtilisin. | escherichia coli glutamine synthetase is inactivated by subtilisin. protection against inactivation is afforded by glutamine and ammonium ions. one large fragment (mr = 35,000) is identified by sodium dodecyl sulfate-gel electrophoresis and carries adenylylation site. smaller quantities of two other fragments (mr = 17,000 and 15,000, respectively) are als observed oo observed on the gel. tthe nicked protein remains dodecameric, as evidenced by electrophoresis and centrifugation. it has retained ... | 1979 | 34613 |
| limited proteolysis of glutamine synthetase is inhibited by glutamate and by feedback inhibitors. | limited proteolysis of glutamine synthetase from escherichia coli has been studied under nondenaturing conditions (ph 7.6, 20 degrees c). trypsin cleaves the polypeptide chain of glutamine synthetase into two principal fragments, mr = about 32,000 and 18,000. the covalently bound amp group is attached to the larger fragment and its presence does not affect cleavage. although the cleaved polypeptide chain does not dissociate under nondenaturing conditions, catalytic activity is lost. chymotrypsin ... | 1979 | 34614 |
| properties of mutants of escherichia coli lacking malic dehydrogenase and their revertants. | mutants of escherichia coli lacking malic dehydrogenase activity (mdh) were incapable of growth on acetate", succinate- or malate/mineral medium. revertants of mdh strains which had regained the ability to grow on c4-dicarboxylic acids could be divided into two distinct classes. one type of revertant had regained the ability to synthesize functional malic dehydrogenase. the other type of revertant still lacked malic dehydrogenase activity but possessed a suppressor mutation which altered the reg ... | 1979 | 34619 |
| glutathione-dependent synthesis of deoxyribonucleotides. characterization of the enzymatic mechanism of escherichia coli glutaredoxin. | | 1979 | 34620 |
| some effects of the administration of endotoxin in mice. specific cleavage of serum albumin by an acid protease and the generation of amyloid serum component. | endotoxin has been shown to induce amyloidosis in mice and to result in the appearance in serum of large amounts of amyloidrelated protein (saa). after injection of 300 mug lipopolysaccharide escherichia coli, saa behaves as an acute phase reactant with levels reaching a peak of >600 mug/ml at 18-22 h and returning to base line (<50 mug/ml) by 48 h in each of four strains tested; only the endotoxin-resistant c3h/hej strain showed a smaller response. lesser, though significant, elevations were al ... | 1979 | 34628 |
| injury and recovery of escherichia coli after sublethal acidification. | over 99% of the viable cells of escherichia coli k-12 were injured after a 60-min exposure to 0.3 m sodium acetate buffer at ph 4.2. injured cells were those able to grow on trypticase soy agar but unable to grow on violet red bile agar. the extent of both death and injury of acid-treated cells increased with decreasing ph or increasing concentration of acid. injured cells were able to recover their colony-forming ability on violet red bile agar by incubation in trypticase soy broth or potassium ... | 1979 | 35097 |
| formation of n-nitrosamines from seconday animes and nitrite by resting cells of escherichia coli b. | in the presence of resting cells of escherichia coli b, the formation of n-nitrosamines from nitrite and secondary amines, such as dimethylamine and piperidine, was proportional to the incubation time and to the cell concentration. optimum ph was 8.0. boiled cells were incapable of nitrosating secondary amines. although these experiments were carried out by using intact cells of e. coli b, the reaction followed michaelis-menten kinetics, and the apparent km values calculated from lineweaver-burk ... | 1979 | 35098 |
| artificially induced active transport of amino acid driven by the efflux of a sugar via a heterologous transport system in de-energized escherichia coli. | consistent with the model of an h+ cotransport, amino acid uptake can be driven by a proton gradient generated by an efflux of sugar when the normal energy sources are suppressed. heterologous countertransport is completely inhibited by uncouplers unlike homologous countertransport. positive coupling was obtained with methyl thiogalactoside/proline, methyl thiogalactoside/phenylalanine, gluconate/proline; however, the poor coupling efficiency suggests a more complex sequence of reactions. | 1979 | 35159 |
| [role of proton motive force in the infection of e. coli k-12 cells by bacteriophage t4]. | it was shown that infection of e. coli cells by phage t4 is suppressed, when the cells are treated by oxidative phosphorylation uncouplers. the inhibiting effects of the uncouplers manifest themselves at the stage of phage dna entry into the cells. study of the e. coli cells devoid of their h+-atpase activity due to mutation showed that the infection is suppressed by a switch-off of the respiratory chain, the only generator of the proton motive force (pmf) in mutated cells. infection of the e. c ... | 1979 | 35241 |
| salicylate blockade of granulocyte adherence and the inflammatory response to experimental peritonitis. | aspirin profoundly inhibited the in vitro augmentation of human and mouse granulocyte adherence to nylon fiber induced by the bacterial products escherichia coli endotoxin and staphylococcus aureus culture filtrate. granulocytes obtained from normal volunteers during the 48 hr following ingestion of aspirin did not respond normally to endotoxin stimulation. furthermore, pretreatment of mice with sodium salicylate prior to intraperitoneal infection with streptococcus pneumoniae impaired granulocy ... | 1979 | 35259 |
| diastereoisomeric glucuronides of oxazepam. isolation and stereoselective enzymic hydrolysis. | oxazepam glucuronide isolated from swine urine by previously published methods was separated into its diastereoisomers by ion-exchange chromatography on a preparative scale. quantitative high-performance liquid chromatography was used to monitor the separation. the two isomers were obtained in analytically pure form and then characterized by elemental analysis, oxazepam content, mass spectrometry, ultraviolet spectroscopy, optical rotation and optical rotatory dispersion-circular dichroism. the ... | 1979 | 35325 |
| effect of storage at 1 degree and 4 degrees c on viability and injury of staphylococcus aureus, escherichia coli and streptococcus faecalis. | | 1979 | 35509 |
| combined use of strain construction and affinity chromatography in the rapid, high-yield purification of 6-phosphogluconate dehydrogenase from escherichia coli. | a rapid, high-yield method for purification of 6-phosphogluconate dehydrogenase from escherichia coli k-12 is described. sonic extracts prepared from heat-induced cultures of strain rw184, doubly lysogenic for the specialized transducing bacteriophage lambdaci857st68h80dgndhis and bearing a deletion of the gene for glucose 6-phosphate dehydrogenase, contained levels of 6-phosphogluconate dehydrogenase 15- to 20-fold higher than cultures of wild-type cells. affinity chromatography on blue dextran ... | 1979 | 35519 |
| respiration-linked proton transport, changes in external ph, and membrane energization in cells of escherichia coli. | the kinetics of respiration-dependent proton efflux and membrane energization have been studied in intact cells of logarithmic-phase escherichia coli. parallel measurements of the rate and extent of proton efflux into the external medium (half-time, about 10 s; ratio of h(+) to o, about 0.5) and the oxidation of e. coli cytochrome b (half-time, </=1 s; about 6% oxidized) after a pulse of 5.5 ng-atoms of o indicate that the rate of proton efflux is at least 10 times slower than expected from the ... | 1979 | 35520 |
| sensitivity of escherichia coli to cephaloridine at different growth rates. | steady-state populations of escherichia coli b/r were treated with cephaloridine at minimal inhibitory concentrations. the antibiotic sensitivity of the cells and the localization of spheroplast emergence along the cell surface were examined as a function of cell length and growth rate. in fast-growing populations (greater than 1 division per h) the sites of cephaloridine interaction occurred preferentially at the cell pole in the smaller cells and at the cell center in dividing cells. at decrea ... | 1979 | 35527 |
| deletion mapping of the pola-metb region of the escherichia coli chromosome. | a lambdaci857 prophage inserted into one of the genes of the rha locus was used to select deletions unambiguously ordering the markers pola-glna-rha-pfka-tpi-metbjf. transduction with phage p1 indicates at least 70% linkage between glna and pola. the order of the pfk and tpi markers is reversed from that previously published. despite the relatively large distance separating the glna and rha loci, deletions removing this entire region have no obvious phenotype. the isolation of tn10 transposons i ... | 1979 | 35528 |
| immunological studies on 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase isoenzymes. | an apparently homogeneous preparation of the phenylalanine-sensitive 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase isoenzyme from escherichia coli was used as the antigen for antibody production in new zealand white rabbits. the antibodies were monospecific as judged by immunodiffusion and immunoelectrophoresis. antigen . antibody complexes maintained full enzyme activity and were inhibited by phenylalanine, indicating that neither the active site nor the feedback-inhibitor binding site i ... | 1979 | 35532 |
| etiology and antimicrobial therapy of acute maxillary sinusitis. | eighty-one adults with symptoms of acute sinusitis were studied by direct needle puncture and aspiration of the maxillary sinus (105 sinuses). fifty-nine bacterial strains were isolated in titers of greater than or equal to 10(4) colony-forming units/ml; streptococcus pneumoniae and haemophilus influenzae accounted for 64% of the isolates. other bacteria recovered included anaerobes (12%), neisseria species (8.5%). streptococcus pyogenes (3%), alpha-hemolytic streptococcus (3%), non-group a beta ... | 1979 | 35571 |
| a new analytical procedure for two-dimensional electrophoresis of cellular proteins: comparison of protein compositions of parent strain and a k+-accumulation mutant of e. coli. | an improved two-dimensional analytical electrophoretic technique fractionates according to molecular weight in the presence of dedecyl sulfate in the first dimension, then fractionates according to isoelectric point in a perpendicular dimension. electrofocusing in the second dimension achieves nearly complete removal of most protein components while providing true estimates of their isoelectric points. because not all proteins penetrate isoelectric focusing gels, some proteins may go unrecognize ... | 1978 | 35802 |
| the prerequisites for local lysolecithin formation in the human gallbladder. iii. demonstration of two different phospholipase a activities. | the positional specificity of the phospholipase a (ec 3.1.1.4) in human gallbladder epithelium has been studied using 14c-phosphatidylethanolamine radiolabeled either in the 1-acyl or in the 2-acyl position. after heating of homogenized epithelial cells at 70 degrees c for 2 min, their lysophospholipase activity was lost. in contrast, the ability to hydrolyze 14c-phosphatidylethanolamine in biosynthetically radiolabeled escherichia coli was largely retained. the amounts of radioactivity found i ... | 1979 | 35826 |
| cation/proton antiport systems in escherichia coli: properties of the sodium/proton antiporter. | | 1979 | 36033 |
| manganese-containing superoxide dismutase from escherichia coli: reversible resolution and metal replacements. | | 1979 | 36037 |
| a microcalorimetric study on the action of penicillins on staphylococcus aureus and escherichia coli. | the heat generated by cultures of a strain of escherichia coli and of a beta-lactamase- and a non-beta-lactamase-producing strain of staphylococcus aureus were registered by a flow microcalorimeter of the heat conduction type. when exposing the non-beta-lactamase-producing strain to benzylpenicillin, an effect that appeared to correspond to the 'paradoxical zone phenomenon' was found, i.e. the inhibitory effect on the bacterial metabolism, as judged from the heat generated, was smaller when usin ... | 1979 | 36262 |
| studies on regulatory functions of malic enzymes. vi. purification and molecular properties of nadp-linked malic enzyme from escherichia coli w. | nadp-linked malic enzyme [ec 1.1.1.40] was highly purified from escherichia coli w cells. the purified enzyme was homogeneous as judged by ultracentrifugation and gel electrophoresis. the apparent molecular weights obtained by sedimentation equilibrium analysis, from diffusion and sedimentation constants, and by disc electrophoresis at various gel concentrations were 471,000, 438,000, and 495,000, respectively. the subunit molecular weights obtained by sedimentation equilibrium analysis in the p ... | 1979 | 36376 |
| [peptidyltransferase center of ribosomes. structure and relationship to other ribosomal functions]. | structural analysis of the ribosomal peptidyl transferase center using model substrates "minimal" peptide acceptors and donors is reported in the present work. recent data on the ribosomal proteins and rrna organizing the peptidyl transferase center and other functional centers of the large ribosomal subunits are given and the know facts about the catalytic mechanism of the peptide bond formation are considered. an analysis of the interaction of the peptidyl transferase center and the centers bi ... | 1977 | 36555 |
| cellular applications of 31p and 13c nuclear magnetic resonance. | high-resolution nuclear magnetic resonance (nmr) studies of cells and purified mitochondria are discussed to show the kind of information that can be obtained in vivo. in suspensions of escherichia coli both phosphorus-31 and carbon-13 nmr studies of glycolysis and bioenergetics are presented. in rat liver cells the pathways of gluconeogenesis from carbon-13-labeled glycerol are followed by carbon-13 nmr. in the intact liver cells cytosolic and mitochondrial ph's were separately measured by phos ... | 1979 | 36664 |
| magnitude of pollution indicator organisms in rural potable water. | a total of 460 water samples were randomly drawn from the potable water supply sources of rural communities in three counties of south carolina. about 10% of the population, not incorporated in municipalities, was sampled. the samples were tested for total coliforms, escherichia coli, and fecal streptococci. significant levels of these pollution indicator organisms were detected in almost all the water supplies. total coliforms were the most common, and only 7.5% of the water supplies were uncon ... | 1979 | 36849 |
| phosphatidylseryl-transfer rna in bacillus licheniformis 749/c. | phosphatidylserine has been found in extracts of bacillus licheniformis made under alkaline conditions but not under neutral or acidic ones and was derived from the trna fraction. in trna preparations kept below neutrality during purification, phosphatidylserine was the only phospholipid released when the ph was raised to 9.0. the amount of bound phosphatidylserine could be increased by incubating trna from b. licheniformis or escherichia coli with ctp and phosphatidic acid in the presence of an ... | 1979 | 36914 |
| polynucleotides xlvii. synthesis and properties of poly(2-methylthio- and 2-ethylthioadenylic acid). formation of non-watson-crick type complexes. | poly(2-methyl- and 2-ethylthioadenylic acid) were prepared by polymerization of corresponding diphosphates with escherichia coli polynucleotide phosphorylase. these polynucleotides have relatively large hypochromicity of 30-35%. acid titration of these polymers showed abrupt transition at ph 5.34-5.4, which may indicate that the introduction of alkylthio group at 2-position of adenine bases reduced their basicity. thermal melting of these polymers showed no clear transition points at neutral ph, ... | 1979 | 36915 |
| nadp-specific isocitrate dehydrogenase of escherichia coli. iv. purification by chromatography on affi-gel blue. | affinity chromatography on affi-gel blue has been used to purify the nadp-specific isocitrate dehydrogenase (ec 1.1.1.42) from escherichia coli. the protocol permits rapid purification of the enzyme in milligram quantities with a yield of 50% and is carried out almost entirely at room temperature. the preparation was judged to be homogeneous by non-denaturing electrophoresis at ph 7.5 and denaturing electrophoresis in the presence of sodium dodecyl sulfate. the subunit molecular weight of 53 000 ... | 1979 | 36923 |
| purification of udp-n-acetylenolpyruvoylglucosamine reductase from escherichia coli by affinity chromatography, its subunit structure and the absence of flavin as the prosthetic group. | the enzyme udp-n-acetylenolpyruvoylglucosamine reductase (ec 1.1.1.158) was purified to homogeneity from escherichia coli by affinity chromatography on a nadp-agarose column. the evidence suggests that the enzyme (molecular weight 35,000) is composed of two nonidentical subunits of molecular weight 21,500 and 13,500, respectively. the absorption spectrum of the purified enzyme shows no absorption band around 450 nm and thus does not support the previous suggestions that the enzyme is a flavoprot ... | 1979 | 36973 |
| formate-nitrite reduction in escherchia coli k12. 1. physiological study of the system. | | 1979 | 37075 |
| kinetic studies of the interaction between ms2 phage and f pilus of escherichia coli. | the kinetics of the binding reaction of ms2 phage to free f pili, which were highly purified from escherichia coli, has been studied using a membrane filter assay. the rate of dissociation (kd) of the ms2-phage--f-pilus complex is very slow and follows first-order kinetics with a half-life of 4.2 h at 30 degrees c in the standard buffer. the dissociation rate is rather insensitive to temperature, but becomes more rapid at high ionic strength or at basic ph. in a 0.25 m ionic strength buffer, the ... | 1979 | 37080 |
| factors affecting release of heat-labile enterotoxin by enterotoxigenic escherichia coli. | various conditions affecting the release of heat-labile enterotoxin (lt) by enterotoxigenic escherichia coli have been examined. the ph of a defined medium containing three amino acids, m-9 salts, and 0.5% glucose decreased to less than 7.0 in early log phase of growth, and no extracellular lt was detected. adjustment of the ph at 8 h from 6.0 to 8.0 resulted in a concomitant increase in lt activity in culture supernatants. the release of cell-associated lt was significantly reduced by preincuba ... | 1979 | 37162 |
| structure of common pili from escherichia coli. | several important properties of the common pili from escherichia coli are discussed. these pili were resistant to the gentle folin-ciocalteau reagent methods for protein detection and were not readily solubilized by sodium dodecyl sulfate. they were found to contain a reducing sugar but not peptidoglycan. the pilin had multiple conformations in sodium dodecyl sulfate solution, and the appearance of multiple bands on sodium dodecyl sulfate gels did not necessarily indicate heterogeneity of the pr ... | 1979 | 37233 |
| reduction of methionine sulfoxide to methionine by escherichia coli. | l-methionine-dl-sulfoxide can support the growth of an escherichia coli methionine auxotroph, suggesting the presence of an enzyme(s) capable of reducing the sulfoxide to methionine. this was verified by showing that a cell-free extract of e. coli catalyzes the conversion of methionine sulfoxide to methionine. this reaction required reduced nicotinamide adenine dinucleotide phosphate and a generating system for this compound. the specific activity of the enzyme increased during logarithmic growt ... | 1979 | 37234 |
| role of lithium ions in proline transport in escherichia coli. | mechanisms of li+ stimulation of proline transport were studied in cells of escherichia coli 7 and nr70, a mutant of strain 7 lacking adenosine triphosphatase (ec 3.6.1.3). an electrochemical potential difference of li+ induced in an inward direction of energy-depleted cells caused a transient uptake of proline depending on the driving force provided. when proline was added to unbuffered cell suspensions under anaerobic conditions, the medium was found to be acidified only in the presence of li+ ... | 1979 | 37240 |
| calcium/proton and sodium/proton antiport systems in escherichia coli. | | 1979 | 37247 |
| interactions between bifidobacterium bifidum n4 and escherichia coli k-12 in their mixed cultures. | the interactions between bifidobacterium bifidum n4 (b. bifidum) and escherichia coli k-12 (e. coli) were investigated in their mixed cultures. under conditions in which both bacteria grew well in their pure culture, b. bifidum inhibited the growth of e. coli even when the latter was inoculated at 10(4)-fold and preincubated for 41 hr. the inhibition in the mixed cultures appeared when the ph values were reduced below 4.6. when the lowering of ph was prevented by the addition of naoh, no inhibit ... | 1978 | 37291 |
| [l-asparatic acid synthesis from ammonium fumarate by free and immobilized escherichia coli cells]. | e. coli 85 cells with a high aspartate-ammonia-lyase activity were immobilized through polyacrylamide gel incorporation. proper conditions to assay aspartase activity of e. coli cells were developed. kinetic patterns of aspartate-ammonia-lyase reaction catalyzed by free and immobilized e. coli 85 cells were studied. the synthesis of l-aspartic acid from ammonium fumarate had the following characteristics: specific activity of (4--6) . 10(-5) mmole/mg.sec for free cells and (6--8) . 10(-5) mmole/ ... | 1979 | 37496 |
| escherichia coli phosphoenolpyruvate dependent phosphotransferase system. nmr studies of the conformation of hpr and p-hpr and the mechanism of energy coupling. | 1h and 31p nuclear magnetic resonance investigations of the phosphoprotein intermediate p-hpr and the parent molecule hpr of the e. coli phosphoenolpyruvate dependent phosphotransferase system (pts) show that hpr can exist in two conformations. these conformations influence the protonation state of the reactive histidine residue, thereby determining the reaction pathway in the phosphoryl group transfer step. a general mechanism is proposed for the energy-coupling process in the pts. | 1979 | 37892 |
| bohr effect in escherichia coli aspartate transcarbamylase. linkages between substrate binding, proton binding, and conformational transitions. | | 1979 | 37893 |
| inactivation of escherichia coli bf1-atpase by dicyclohexylcarbodiimide. chemical modification of the beta subunit. | | 1979 | 37896 |
| arginyl-trna synthetase from escherichia coli k12. purification, properties, and sequence of substrate addition. | arginyl-trna synthetase from escherichia coli k12 has been purified more than 1000-fold with a recovery of 17%. the enzyme consists of a single polypeptide chain of about 60 000 molecular weight and has only one cysteine residue which is essential for enzymatic activity. transfer ribonucleic acid completely protects the enzyme against inactivation by p-hydroxymercuriben zoate. the enzyme catalyzes the esterification of 5000 nmol of arginine to transfer ribonucleic acid in 1 min/mg of protein at ... | 1979 | 37899 |
| poly(2-fluoroadenylic acid). the role of basicity in the stabilization of complementary helices. | the polymerization of 2-fluoroadenosine 5'-diphosphate by polynucleotide phosphorylase to give high molecular weight poly(2-fluoroadenylic acid), poly(fl2a), is described. both the single-stranded and double-stranded (acid) forms of poly(fl2a) exhibit strikingly similar ultraviolet and circular dichroism spectra to those of poly(a), and the enzymatic polymerization rates and thermal hyperchromicities of the two polymers are also very similar. however, the pka of poly(fl2a) for protonation at n-1 ... | 1979 | 37911 |
| [transhydrogenase as an additional site of energy accumulation in the e. coli respiratory chain]. | nad+ reduction catalyzed by transhydrogenase (ec 1.6.1.1) from e. coli membrane particles at the expense of nadph oxidation is coupled with phenyldicarbaundecaborate (pcb-) absorption by the particles. this process is inhibited by oxidative phosphorylation protonophorous uncouplers and by equilibration of concentrations of the substrates and products of the transhydrogenase reaction. elimination of the water-soluble part of membrane atpase results in the inhibition of pcb- absorption at the expe ... | 1979 | 37931 |
| [guanylate cyclase in escherichia coli. i. purification of the enzyme and evidence for an inhibitor]. | guanylate cyclase activity is present in crude e. coli extract. guanylate cyclase has been purified 3500 fold from this extract, through ammonium sulfate fractionation, deae-cellulose chromatography. sephadex g-75 gel-filtration and polyacrylamide gel preparative microelectrophoresis. during the purification a guanylate cyclase inhibitor has been separated. | 1978 | 37997 |
| [guanyl cyclase in escherichia coli. ii. identification and characteristics on the enzyme inhibitor]. | the activity of guanylate cyclase and that of its inhibitor present in e. coli extract, have been separated through a linear kcl gradient on deae-cellulose column. the activity of the inhibitor is lost after ribonuclease treatment, whereas is strengthened by addition of poly (c). other types of rna synthetic homopolymers do not affect the inhibitor's activity. chromatographic analysis of the products of guanylate cyclase measured in the presence of fi and fi plus poly (c), indicated that the inh ... | 1978 | 37998 |
| analogs of l-aspartic acid in chemotherapy for cancer. | the interaction of analogs of l-aspartic acid with adenylosuccinic acid synthetase, l-asparagine synthetase, and l-aspartic acid transcarbamylase is discussed. each of these enzymes is of critical importance in the economy of certain types of tumor cells. l-alanosine, a new antitumor antibiotic, is shown to be accepted as a substrate by the enzymes of de novo purine biosynthesis which ordinarily use l-aspartic acid as a substrate; as a consequence of this interaction, an anabolite is thought to ... | 1979 | 38003 |
| adherence of escherichia coli to human urinary tract epithelial cells. | the adherence of escherichia coli to human uroepithelial cells obtained from midstream urine specimens of healthy women was studied. bacteria labeled with [(3)h]uridine were used, and unattached organisms were separated from the epithelial cells by vacuum filtration with 5-mum-pore-size nucleopore membrane filters. these techniques allowed adherence to be measured in large numbers of epithelial cells and overcame the problem of distinguishing experimental bacteria from the indigenous organisms p ... | 1979 | 38207 |
| active groups of bicyclomycin and the reaction with thiols. | the binding of [14c]bicyclomycin to whole cells of e. coli and to the inner membrane proteins was inhibited by dithiothreitol and 2-mercaptoethanol. the reactivity of the drug with the sulfhydryl group was further studied, using methanethiol as a model compound. the kinetics revealed that the reaction was of pseudo-first-order in excess of thiolate anion. analysis with gas chromatography-mass spectrometry showed that the main product was an adduct of thiol with bicyclomycin in an equal molar rat ... | 1979 | 38239 |
| proton magnetic resonance studies on escherichia coli dihydrofolate reductase. assignment of histidine c-2 protons in binary complexes with folates on the basis of the crystal structure with methotrexate and on chemical modifications. | the effects of ph upon the c-2 resonances of the 5 histidine residues of escherichia coli mb 1428 dihydrofolate reductase in binary complexes with methotrexate, aminopterin, folate, methopterin, and trimethoprim were studied by 300-mhz 1h nmr spectroscopy. three of the five histidine residues, labeled 1, 2, and 3, exhibited similar pk' values and chemical shifts for their c-2 protons in the five binary complexes. one histidine, 4, was quite different in the folate complex and the last histidine, ... | 1979 | 38247 |
| energy-transducing h+-atpase of escherichia coli. purification, reconstitution, and subunit composition. | | 1979 | 38249 |
| the membrane potential in everted vesicles of escherichia coli. | | 1979 | 38747 |
| mechanism of lactose translocation in membrane vesicles from escherichia coli. 1. effect of ph on efflux, exchange, and counterflow. | | 1979 | 38836 |
| mechanism of lactose translocation in membrane vesicles from escherichia coli. 2. effect of imposed delata psi, delta ph, and delta mu h+. | | 1979 | 38837 |
| the reactions of escherichia coli citrate synthase with the sulfhydryl reagents 5,5'-dithiobis-(2-nitrobenzoic acid) and 4,4'-dithiodipyridine. | citrate synthase of escherichia coli reacts rapidly with 1 equivalent of ellman's reagent, 5,5'-dithiobis-(2-nitrobenzoic acid) (dtnb), per subunit, losing completely its sensitivity to the allosteric inhibitor, nadh. when the enzyme is treated instead with 4,4'-dithiodipyridine (4,4'-pds), all activity is lost. certain evidence in this paper is consistent with the belief that the sulfhydryl group modified by dtnb, and that whose modification by 4,4'-pds inactivates the enzyme, are the same. (i) ... | 1979 | 38891 |
| phosphate uptake in chemostat cultures of escherichia coli k-12 subjected to periodic beta-glycerophosphate pulsing: a system for assaying alkaline phosphatase. | limiting concentrations of beta-glycerophosphate were pulsed into chemostat cultures of escherichia coli k-12 at intervals equal to the population doubling time. the resultant culture density fluctuations are interpreted in terms of inorganic phosphate uptake which, in this system, is a function of alkaline phosphatase activity. information concerning in vivo alkaline phosphatase activity at suboptimal (acidic) ph with very low concentrations of substrate (beta-glycerophosphate) is obtained from ... | 1979 | 38894 |
| formation of okazaki pieces at the escherichia coli replication fork in vitro. | | 1979 | 38946 |
| myeloperoxidase-hydrogen peroxide-chloride antimicrobial system: effect of exogenous amines on antibacterial action against escherichia coli. | exogenous ammonium ions (nh(4) (+)) and amine compounds had a profound influence on the antibacterial activity of the myeloperoxidase-hydrogen peroxide-chloride system against escherichia coli. the rate of killing increased in the presence of nh(4) (+) and certain guanidino compounds and decreased in the presence of alpha-amino acids, polylysine, taurine, or tris (hydroxymethyl) aminomethane. myeloperoxidase catalyzed the oxidation of chloride to hypochlorous acid, which reacted either with bact ... | 1979 | 39030 |
| immunization of calves against enterotoxigenic colibacillosis by vaccinating dams with purified k99 antigen and whole cell bacterins. | pregnant cattle were either vaccinated subcutaneously with (i) a suspension of purified escherichia coli k99 pili, (ii) a formalin-killed whole cell bacterin containing enterotoxigenic e. coli strain b44 (o9:k30;k99:h-), or (iii) a bacterin containing six different strains of bovine enterotoxigenic e. coli (multiple-strain bacterin), or were left as nonvaccinated controls. after birth, calves were allowed to nurse their dams and, at 12 to 14 h of age, were challenged orally with 10(11) cells of ... | 1979 | 39031 |
| extrusion of sodium ions energized by respiration and glycolysis in escherichia coli. | extrusion of sodium ion from cells of escherichia coli was measured using an na+ electrode. when oxygen was supplied to an anaerobic cell suspension, extrusion of na+ was observed. the addition of glucose under anaerobic conditions also caused na+ efflux. the extrusion of na+ energized by respiration and glycolysis was completely inhibited by a proton conductor, carbonyl cyanide m-chlorophenylhydrazone. these observations are consistent with the view that na+ transport occurs secondarily to h+ c ... | 1979 | 39066 |
| cessation of respiration after far-ultraviolet irradiation of escherichia coli b/r: loss of unaltered pyridine nucleotides to the medium. | | 1979 | 39314 |
| recovery from lethal escherichia coli shock in dogs. | | 1979 | 39354 |
| microbiological activity of cefazedone as compared to cefazolin and cephalothin. | in a comparison of the antibacterial activity of (6r,7r)-7-(2-[3,5-dichloro-4-oxo-1(4h)-pyridyl]-acetamido)-3-([5-methyl-1,3,4-thiadiazol-2-yl)-thio]methyl)-8-oxo-5-thia-1-azabicyclo[4,2,0]oct-2-ene-2-carboxylic acid (cefazedone, refosporen) as compared to other cephalosporins it can be seen that cefazedone possesses good activity against gram-positive bacteria; as regards activity against enterobacteriaceae, in particular strains of e. coli, klebsiella species and proteus mirabilis, they fall w ... | 1979 | 39575 |
| the purification of glutamine synthetase from azotobacter and other procaryotes by blue sepharose chromatography. | we report the facile purification of glutamine synthetase (l-glutamate: ammonia ligase (adenosine 5'-diphosphate-forming), ec 6.3.1.2) in both the adenylylated and unadenylylated form, from azotobacter vinelandii atcc 12837. a general affinity column, which used as an affinity ligand reactive blue 2 dye (cibacron blue) covalently linked to agarose, was employed as an efficient first step of purification. further purification to electrophoretic homogeneity employed deae-cellulose chromatography a ... | 1979 | 39606 |
| immobilization of escherichia coli cells containing aspartase activity with kappa-carrageenan. enzymic properties and application for l-aspartic acid production. | whole cells of escherichia coli having high aspartase (l-asparate ammonialyase, ec 4.3.1.1) activity were immobilized by entrapping into a kappa-carrageenan gel. the obtained immobilized cells were treated with glutaraldehyde or with glutaraldehyde and hexamethylenediamine. the enzymic properties of three immobilized cell preparations were investigated, and compared with those of the soluble aspartate. the optimum ph of the aspartase reaction was 9.0 for the three immobilized cell preparations a ... | 1979 | 39611 |
| physiological change in the ionophore-portion of proton-translocating atpase in an uncoupled mutant of escherichia coli. | | 1979 | 39783 |
| evidence suggesting that the nadph/nadp ratio modulates the splitting of the isocitrate flux between the glyoxylic and tricarboxylic acid cycles, in escherichia coli. | | 1979 | 39785 |
| production of heat-stable, methanol-soluble enterotoxin by yersinia enterocolitica. | seven isolates of yersinia enterocolitica serotype 0:8, recovered during an outbreak of gastrointestinal illness, were examined for enterotoxin production. all seven strains were enterotoxigenic in the suckling mouse model, and three of five isolates tested produced keratoconjunctivitis in the guinea pig eye model (sereny test). enterotoxin was detected in broth supernatant fluid after 12 h of incubation at 25 degrees c. the toxin was not inactivated by exposure to 121 degrees c for 30 min or by ... | 1979 | 39891 |
| purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic escherichia coli. | heat-labile enterotoxin (lt) produced by a human strain of enterotoxigenic escherichia coli (286c(2)) was purified to homogeneity from ph extracts of fermentor-grown cells by ultrafiltration, (nh(4))(2)so(4) fractionation, hydrophobic chromatography on norleucine-sepharose 4b, hydroxylapatite chromatography, and bio-gel p-150 filtration. purified lt preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (y-1 adrenal tumo ... | 1979 | 39893 |
| mechanism of action of yersinia enterocolitica enterotoxin. | enterotoxin derived from three clinical isolates of yersinia enterocolitica was compared with the heat-stable enterotoxin of escherichia coli. both toxins were biologically active in infant mice examined at 2 h and in ligated rabbit ileal loops at 6 h. neither substance, however, produced changes in ligated ileal loops at 18 h or in chinese hamster ovary or y1 adrenal tissue cultures. in addition, both y. enterocolitica enterotoxin concentrated approximately 20 times by ammonium sulfate precipit ... | 1979 | 39894 |
| purification and characterization of the cfa/i antigen of enterotoxigenic escherichia coli. | the fimbral colonization factor antigen cfa/i of enterotoxigenic escherichia coli was purified and characterized. the initial purification step was release of these fimbriae from the bacterial cells by homogenization with a waring blender. common fimbriae and flagellar antigen were avoided by careful control of growth conditions and the use of a nonmotile (h-) mutant of the prototype strain h-10407 (o78:h11). the essential purification steps were membrane filtration (millipore corp.), ammonium s ... | 1979 | 39896 |
| specificity and mode of cleavage of the ph 4.0 endonuclease from adenovirus type 2 - infected kb cells. | adenovirus type 2 or lambda dna was digested with the ph 4.0 endonuclease, purified from adenovirus 2-infected kb cells. the enzyme produces a limit digest of approximate size in the range of 140-210 base pairs long. the termini of the dna fragments generated by the endonuclease digestion had 3'-p and 5'-oh groups. the 3' and 5' end groups of the products were analyzed. our data indicate that 3' end group was a purine (68-76%), da occuring about twice the frequency of dg. the 5' end group was ei ... | 1979 | 40209 |
| [plasmid identification in e. coli cells of natural origin]. | | 1979 | 40370 |