| evidence for quantitative variability of bacterial opsonic requirements. | we studied human serum opsonins by using combinations of heat inactivation and chelation to inhibit complement, adsorption to remove antibody, and trypan blue to inactivate the c3 receptor of human polymorphonuclear leukocytes. streptococcus pneumoniae, serotype 25, required both complement and immunoglobulin for opsonization, even though that strain activated the alternative complement pathway. both strains of escherichia coli required antibody and complement, but varied in the degree of depend ... | 1978 | 25243 |
| cell-free biosynthesis of the o-acetylated n-acetylneuraminic acid capsular polysaccharide of group c meningococci. | a cell-free system was established to study the biosynthesis of group c meningococcal capsular polysaccharide, an alpha-2 leads to 9-linked n-acetylneuraminic acid (neuac) homopolymer containing o-acetyl groups at either c7 or c8. sialyltransferase activity, isolated from group c meningococcus strain c-11, catalyzed incorporation of 14cneuac from cmp (cmp--14cneuac) into polymeric form. this sialyltransferase was stimulated by addition of meningococcus group c and escherichia coli k92 capsular p ... | 1978 | 25263 |
| specific agglutination of escherichia coli o128b12 by the mannose-binding proteins of pseudomonas aeruginosa. | the mannosephilic haemagglutinins of pseudomonas aeruginosa were found to agglutinate cells of escherichia coli o128b12, to be adsorbed onto them and to attach peroxidase to them. these reactions were specifically inhibited by d-mannose. no agglutination by this pseudomonas haemagglutinin was obtained when several other enteropathogenic types of escherichia coli and some other gram-negative bacteria were examined. concanavalin a, which also reacted with escherichia coli o128b12 cells, interacted ... | 1977 | 25370 |
| turbidimetric and potentiometric studies of ribosomal subunits from an erythromycin resistant mutant of escherichia coli. | turbidimetric and potentiometric techniques were applied to the analysis of an eryr mutant. results show that in the mutant, the 30s subunits are drastically altered, as indicated by a higher mg2+ requirement for subunit association and by an important difference in the titratable groups. replacement of parental 50s by mutant 50s subunits does not decrease the association capacity with 30s parental subunits, but a structural difference is detected in the mutant 50s with potentiometric measuremen ... | 1978 | 25415 |
| evidence that proteins s1, s11 and s21 directly participates in the binding of transfer rna to the 30s ribosome. | in a previous publication1 we reported that the tyrosine selective reagent, tetraitromethane, causes complete inactivation of e. coli 30s ribosomes for poly u directed non-enzymatic phe-trna binding. this inactivation was demonstrated to be due to the chemical modification of the protein moiety of the ribosome. we have no identified the proteins of the 30s particle inactivated by this modification. using a method of ribosome reconstruction we have found that unmodified proteins s1, s11, and s21 ... | 1978 | 25421 |
| functional properties of beta-galactosidase from mutant strain 13 po of escherichia coli. | the functional properties of czp protein, a mutant deriving from wild-type beta-galactosidase (beta-d-galactoside galactohydrolase; ec 3.2.1.23) by a point mutation, were investigated. a large decrease of the specificity, as evaluated by the kcat/km ratio, was observed, principally originated by a weaker binding of the substrates. the catalytic constants, whose values are strongly affected by the presence of divalent cations, were smaller or larger for mutant enzyme than for wild-type enzyme, de ... | 1978 | 25441 |
| characterization of a cacl2-dependent transfection system of escherichia coli and dna of phage lambda. | | 1978 | 25510 |
| physiology of l-asparaginase synthesis in recombinants of escherichia coli a-1. | a mating between escherichia coli 4318 (thi leu las- hfr) and e. coli a-1 (met- las+ f-) resulted in the formation of prototrophic recombinants having l-asparaginase activities at three distinct levels. the physiology of l-asparaginase synthesis in these recombinants is decribed. one class of recombinants produced significantly more l-asparaginase than e. coli a-1. l-asparaginase synthesis in the recombinants was inhibited by the presence of dissolved oxygen in the medium and was transiently rep ... | 1978 | 25625 |
| use of salicylic acid to measure the apparent intracellular ph in the ehrlich ascites-tumor cell and escherichia coli. | the distribution of salicylic acid between the intracellular and extracellular phases has been used to estimate the intracellular ph in the ehrlich cell and escherichia coli. the validity of the method was established by: (i) comparison of the results obtained with salicylic acid with those obtained with 5,5-dimethyloxazolidine-2,4-dione; (ii) by following changes of the apparent intracellular ph under circumstances in which such changes are predictable, e.g., the addition of weak acids or proto ... | 1978 | 25670 |
| sulfate-mediated affinity chromatography on nadp+-sepharose of glutamate dehydrogenase from halophilic bacteria and of glucose-6-phosphate dehydrogenase from escherichia coli. | an improved synthesis of the 8-(6-aminohexyl)amino derivative of nadp+ is described for use in affinity chromatography. the binding of glutamate dehydrogenase isolated from halobacterium of the dead sea on a column of sepharose linked to this nadp+ derivative could be drastically enhanced by addition of sulfate (1m) and provided a tool for partially purifying the enzyme from a crude extract. a similar finding is reported for glucose-6-phosphate dehydrogenase in crude extracts of escherichia coli ... | 1978 | 25766 |
| the proton-consuming site of the respiratory nitrate reductase of escherichia coli is on the cytoplasmic aspect of the cytoplasmic membrane proceedings. | | 1978 | 25819 |
| oxygen-limited continuous culture and respiratory energy conservation in escherichia coli. | escherichia coli b was cultured continuously in succinate-minimal medium under conditions of oxygen limitation in the phauxostat. with decreasing oxygenation and consequent decreasing growth rates, the complement of terminal cytochrome oxidases changed as follows: high growth rates, cytochrome o; intermediate growth rates, cytochromes o and d; lowest growth rates, cytochromes o, d, and a1. respiratory kinetics exhibited by nongrowing cell suspensions obtained from continuous cultures indicated t ... | 1978 | 25879 |
| assimilatory sulfate reduction in an escherichia coli mutant lacking thioredoxin activity. | an investigation of sulfate reduction in b tsnc*7004, a mutant of escherichia coli lacking thioredoxin, is reported. although thioredoxin is indispensable for the adenosine 3'-phosphate 5'-phosphosulfate (paps) sulfotransferase reaction under the usual conditions of assay in extracts of wild-type cells, the mutant grew as well as the wild type on sulfate, indicating that sulfate reduction is not rate limiting for growth. another cofactor for the paps sulfotransferase reaction was found in extrac ... | 1978 | 25880 |
| role of na+ and li+ in thiomethylgalactoside transport by the melibiose transport system of escherichia coli. | thiomethyl-beta-galactoside (tmg) accumulation via the melibiose transport system was studied in lactose transport-negative strains of escherichia coli. tmg uptake by either intact cells or membrane vesicles was markedly stimulated by na+ or li+ between ph 5.5 and 8. the km for uptake of tmg was approximately 0.2 mm at an external na+ concentration of 5 mm (ph 7). the alpha-galactosides, melibiose, methyl-alpha-galactoside, and o-nitrophenyl-alpha-galactoside had a high affinity for this system ... | 1978 | 25882 |
| short rna chains synthesized at low ph are initiated at promoter sites. | under non optimal conditions- either with limiting substrate concentrations (1) or at low ph (2)- rna polymerase of escherichia coli synthesizes very short rna chains. by sequencing one rna species synthesized at ph 5.8 upon t7 dna we were able to demonstrate that under these conditions transcription is initiated at a normal promoter site (here a1) but however is terminated soon afterwards at specific artificial sites not used in vivo. | 1978 | 26044 |
| minichromosome from bk virus as a template for transcription in vitro. | bk virus dna can be extracted from virions as a nucleoprotein complex containing about 20 nucleosomes. transcription of this "minichromosome" with escherichia coli rna polymerase indicates that both initiation and elongation of rna chains are reduced by the presence of nucleosomes. hybridization analysis of rna made on the complex shows preferential transcription of one region of bk virus genome. no increase in strand selection is observed with respect to transcription of purified superhelical b ... | 1978 | 26051 |
| topographical analysis of regulatory and metal ion binding sites on glutamine synthetase from escherichia coli: 13c and 31p nuclear magnetic resonance and fluorescence energy transfer study. | the paramagnetic effect of mn(ii) on (13)c and (31)p nuclear magnetic resonance signals from the 2-(13)catp adenylylated glutamine synthetase l-glutamate:ammonia ligase (adp-forming); ec 6.3.1.2 from escherichia coli was measured. this effect permitted the determination of distances from the 2-c position and the phosphorus of covalently bound amp to the two mn(ii) binding sites, n(1) and n(2). binding of mn(ii) to the n(1) site converts an inactive apo-enzyme to its active form, while the metal ... | 1978 | 26053 |
| the influence on efficacy of formaldehyd and phenol against bacterial cells i. effect of drying, cations and ph-value (author's transl). | 1. when cells of e. coli and staph. aureus are dried, the efficacy of phenol is reduced but the efficacy of formaldehyde is increased. 2. a change of the aw-value by addition of salts changes the efficacy of formaldehyde as well as that of phenol. for these tests the chlorides of various alkali and alkaline earth metals were used in different concentrations. 3. the optimal efficacy of phenol and formaldehyde within the tested concentration gradientis caused by different concentrations of the ion ... | 1978 | 26155 |
| biochemical aspects of cardiac muscle differentiation. | experiments were designed to determine whether dna synthesis ceases in terminally differentiating cardiac muscle of the rat because the activity of the putative replicative dna polymerase (dna polymerase alpha) is lost or whether the activity of this enzyme is lost because dna synthesis ceases. dna-template availability and 3'-hydroxyl termini in nuclei and chromatin, isolated from cardiac muscle at various times during the developmental period in which dna synthesis and the activity of dna poly ... | 1978 | 26332 |
| maleimide ii--interaction with l-asparaginase from escherichia coli. | | 1978 | 26352 |
| incomplete aminoacylation of trnaleu catalyzed in vitro by leucyl-trna synthetase from escherichia coli b. | the extent of esterification of 14c leucine into escherichia coli b trnaleu apparently depends on the concentration of leucyl-trna synthetase. the effect is more pronounced at ph 9.0 than at ph 7.4. when reciprocals of leucyl-trna concentration at plateau aa-trna-1 are plotted against reciprocals of initial velocities vo-1 of aminoacylations a straight line is obtained with a slope equal to the rate constant of non-enzymatic deacylation of leucyl-trna. factors which change the stability of leucy ... | 1978 | 26406 |
| effect of temperature on fluorescence and circular dichroism of escherichia coli dihydrofolate reductase and its complexes. | dihydrofolate reductase and its complexes have been studied by fluorescence and circular dichroism. nadph, trimethoprim, pyrimethamine, or methotrexate binding causes small changes in the enzyme far ultraviolet cd which possibly arise from alterations in polypeptide backbone of the enzyme; however, their effects on enzyme far ultraviolet cd are also explained as the result of ligand interactions with enzyme aromatic groups. in ternary complexes of the enzyme, fluorescence properties of bound nad ... | 1978 | 26417 |
| acetate kinase chromatography on agarose derivatives. | acetate kinase from e. coli k-12 was studied chromatographically on omega-aminoalkyl polysacharide sorbents. the dependence of the protein sorption-desorption on ionic strength and the effect of ph on the acetate kinase sorption were studied. the increase in the ionic strength caused a decrease in the amount of protein sorbed on the hexamethylenediamine- and chlorotriasinehexamethylenediamine sepharoses. on hexamethylenediamine-, octamethylenediamine- and dimethylhexamethylenediamine agaroses ac ... | 1978 | 26422 |
| chorismate mutase/prephenate dehydratase from escherichia coli k12. effect of phenylalanine, nacl and ph on the protein conformation. | the effects of phenylalanine, nacl and ph on the conformation of chorismate mutase/prephenate dehydratase have been investigated, using measurements of far and near-ultraviolet circular dichroic spectra and ultraviolet difference spectra. at ph 8.2 in 20 mm tris-cl buffer the enzyme was found to contain 10-20% helix and 40-50% beta-structure. there was little or no change in these values on the addition of 1 mm phenylalanine (the allosteric effector) or 0.4 m nacl or by decreasing the ph to 7.4. ... | 1978 | 26561 |
| chorismate mutase/prephenate dehydratase from escherichia coli k12. binding studies with the allosteric effector phenylalanine. | the binding of phenylalanine to the allosteric site of chorismate mutase/prephenate dehydratase has been studied by steady-state dialysis. under most of the experimental conditions examined positive co-operativity was observed for the binding of ligand up to 50% saturation and negative co-operativity above 50% saturation. in the presence of 0.4 m nacl at ph 8.2 the co-operativity was positive at all phenylalanine concentrations and the maximal stoichiometry of 1 mol of phenylalanine/mol of enzym ... | 1978 | 26562 |
| regulation of glutamine synthetase formation in escherichia coli: characterization of mutants lacking the uridylyltransferase. | a lambda phage (lambdank55) carrying the translocatable element tn10, conferring tetracycline resistance (tetr), has been utilized to isolate glutamine auxotrophs of escherichia coli k-12. such strains lack uridylyltransferase as a result of an insertion of the tn10 element in the glnd gene. the glnd::tn10 insertion has been mapped at min 4 on the e. coli chromosome and 98% contransducible by phage p1 with dapd. a lambda transducing phage carrying the glnd gene has been identified. a glnd::tn10 ... | 1978 | 26660 |
| 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase. purification and molecular characterization of the phenylalanine-sensitive isoenzyme from escherichia coli. | the phenylalanine-sensitive 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 4.2.1.15) was purified to apparent homogeneity from extracts of escherichia coli k12. the enzyme has a molecular weight of 140,000 as judged by gel filtration and sedimentation equilibrium analysis. the enzyme has a subunit molecular weight of 35,000 as determined by polyacrylamide gel electrophoresis in the pr ... | 1978 | 26682 |
| the effect of ph on the cooperative behavior of aspartate transcarbamylase from escherichia coli. | saturation curves of activity versus concentration were determined for aspartate transcarbamylase from escherichia coli (ec 2.1.3.2) for the substrate l-aspartate at saturating carbamyl phosphate (4.8 mm) in buffered solution at ph values from 6.0 to 12.0. hill coefficients were obtained from the sigmoidal curves. at ph values from 7.8 to 9.1, where substrate inhibition causes difficulties in the hill approximation, our kinetic scheme includes substrate inhibition and residual activity in the ab ... | 1978 | 26686 |
| localization of d-amino acid oxidase on the cell surface of human polymorphonuclear leukocytes. | the ultrastructural localization of d-amino acid oxidase (dao) was studied cytochemically by detecting sites of hydrogen peroxide production in human polymorphonuclear leukocytes (pmns). reaction product, which forms when cerous ions react with h2o2 to form an electron-dense precipitate, was demonstrated on the cell surface and within the phagosomes of phagocytically stimulated cells when d-amino acids were provided as substrate. resting cells showed only slight activity. the competitive inhibit ... | 1978 | 26690 |
| mode of action of colicin ia: effect of colicin on the escherichia coli proton electrochemical gradient. | by use of the technique of flow dialysis, the membrane potential (deltapsi) and ph gradient (deltaph) have been measured in colicin ia-treated escherichia coli k-12 cells and in membrane vesicles prepared from such cells. although such cells and vesicles are able to generate a transmembrane deltaph at ph 5.5, they do not generate a transmembrane deltapsi. glucose-6-phospate uptake by cells is shown to be stimulated at ph 5.5 and inhibited at ph 7.5 by colicin ia treatment. on the other hand, pro ... | 1978 | 26912 |
| heat-stable enterotoxin of escherichia coli: in vitro effects on guanylate cyclase activity, cyclic gmp concentration, and ion transport in small intestine. | a partially purified preparation of the heat-stable enterotoxin of escherichia coli caused a rapid and persistent increase in electric potential difference and short-circuit current when added in vitro to the luminal surface of isolated rabbit ileal mucosa. as little as 1 ng/ml produced an easily detectable response. under short-circuit condition, the enterotoxin abolished net cl- absorption; this change was half that produced by theophylline, which stimulated net secretion. the enterotoxin did ... | 1978 | 26915 |
| a new model for the study of septic shock. | septic shock was produced in 28 healthy mongrel dogs by injecting 10(8) escherichia coli organisms per kilogram into the gallbladder following division of the cystic artery and duct. based upon the circulatory responses and the mortality, two distinct groups emerged. in one, the cardiac index decreased significantly, and the total peripheral resistance was elevated. in the other, the cardiac index increased significantly, and the total peripheral resistance was significantly lower. the average s ... | 1978 | 26983 |
| studies on diarrhea of young calves. 1. quantitative analysis of the gastrointestinal flora in clinically healthy calves and in calves with diarrhea. | quantitative composition of gastro-intestinal-flora was determined in 23 clinically healthy calves and the course of germ spreading was followed up. in comparison with these healthy animals in 25 diarrhoea affected calves at the age of 4 to 17 days there could be observed signigicant differences only in few parts of the gastro-intestinal-tract concerning the quantitative composition of germ flora. only in 3 animals enterotoxin producing e coli strains could be detected. | 1978 | 27162 |
| the effects of acridine orange on deoxyribonucleic acid in escherichia coli. | 1. acridine orange inhibits growth of escherichia coli k12 when incubated at ph 7.9, but not at ph 7.4.2. at a non-permissive temperature for dna polymerase i, acridine orange inhibits growth of a temperature-sensitive strain and also increases the rate of elimination of the f'-lac plasmid. 3. dna isolated from cells treated with acridine orange under conditions that inhibit growth contains material of low molecular weight, which is absent from dna isolated from cells treated under conditions in ... | 1978 | 27167 |
| electron-paramagnetic-resonance studies on nitrate reductase from escherichia coli k12. | nitrate reductase was purified from anaerobically grown escherichia coli k12 by a method based on the triton x-100 extraction procedure of clegg(1976) biochem. j.153, 533-541, but hydrophobic interaction chromatography was used in the final stage. e.p.r. spectra obtained from the enzyme under a variety of conditions are well resolved and were interpreted with the help of the computer-simulation procedures of lowe (1978) biochem. j.171, 649-651. parameters for five molybdenum(v) species from the ... | 1978 | 27168 |
| phosphate transport and the stoicheiometry of respiratory driven proton translocation in escherichia coli. | | 1978 | 27190 |
| the control of pyruvate kinases of escherichia coli: further studies of the enzyme activated by ribose-5-phosphate. | the pyruvate kinase activated by ribose-5-phosphate from escherichia coli has been purified to homogeneity, taking advantage of the stabilization of the enzyme by its inhibitor phosphate and by thiol reagents. the native enzyme has a tetrameric quaternary structure which, while prone to dissociation under many conditions, remains intact in the presence of the above reagents. the enzyme was found to reactivate on dilution out of 8 m urea. interestingly, the recovery of activity is greatly increas ... | 1978 | 27294 |
| heat-stable enterotoxin from escherichia coli: factors involved in growth and toxin production. | six enterotoxigenic strains of escherichia coli produced variable levels of heat-stable enterotoxin (st) when grown under ph control at 8.5 in a simple synthetic medium containing neither amino acids nor vitamins. bacterial growth and st production were at levels as high as or higher than those observed in complex media. st elaboration was detectable in the early logarithmic phase of growth and appeared to be related to disappearance of glucose in the growth medium. the results of this study did ... | 1978 | 27456 |
| 1-n hapa gentamicin b, a new aminoglycoside active against gentamicin resistant isolates--activity compared to other aminoglycosides. | 1-n hapa gentamicin b is a new aminoglycoside active against most enterobacteriaceae, pseudomonas aeruginosa and staphylococcus aureus. among 504 clinical isolates at a concentration of 12.5 microgram/ml all staph. aureus, escherichia coli, klebsiella, enterobacter, proteus rettgeri, providencia and 78% of pseudomonas, 86% of proteus morganii were inhibited. like other aminoglycosides, the activity was greatest at an alkaline ph and reduced by high cations concentrations. 1-n hapa gentamicin b w ... | 1978 | 27494 |
| glycolipids stimulate dna polymerase activity in a dna-membrane fraction and in a partially purified polymerase system extracted from pneumococci. | we have assayed the ability of various lipids to affect dna polymerases activity in a dna-membrane complex extracted from streptococcus pneumoniae by the sarkosyl-m-band technique. in addition, to determine which dna polymerases were affected by the lipids, we partially purified three dna polymerase activities from cell lysates, the first such demonstration outside of escherichia coli and bacillus subtilis. glycolipids are unique among polar lipids in stimulating the rate and extent of dna polym ... | 1978 | 27501 |
| epr investigation of the mn(ii) binding sites in glutamine synthetase (escherichia coli w). i. high-affinity binding sites. | | 1978 | 27502 |
| epr investigation of the mn(ii) binding sites in glutamine synthetase (escherichia coli w). ii. intermediate-affinity binding sites. | the nature of the intermediate-affinity (n2) mn(ii) binding sites in glutamine synthetase ec 6.3.1.2 has been studied as a function of adenylylation in a variety of enzyme-metal complexes by epr. in the absence of nucleotide the n2 mn(ii) environment is nearly isotropic, the mn(ii) bonds are highly ionic, and the interaction distance r greater than or equal to 12-14 a. nucleotide binding at the n2 mn(ii) site renders the n2 mn(ii) signal unobservable and causes a reduction in signal amplitude (a ... | 1978 | 27503 |
| an efficient in vitro total reconstitution of the escherichia coli 50s ribosomal subunit. | a new, relatively simple technique for the total invitro reconstitution of e. coli 50s ribosomes has been developed. it is a two-step procedure like that previously reported by nierhaus and dohme proc. natl. acad. sci. 71, 4713 (1974), but it differs in a number of important aspects. ribosomal rna is prepared by direct phenol extraction of 70s particles to minimize nuclease fragmentation. a mixture of 50s proteins is prepared by acetic acid extraction and immediate removal of the acetic acid by ... | 1978 | 27764 |
| 31p nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic escherichia coli cells. | 31p nuclear magnetic resonance spectra of glycolyzing, anaerobic escherichia coli cells and their perchloric acid extracts were obtained at 145.7 mhz. time-dependent intracellular concentrations of nucleoside di- and triphosphates, pi, and sugar phosphates were measured during glycolysis with 2-min resolution, while intracellular and extra-cellular ph values were monitored simultaneously. upon glucose addition, anaerobic e. coli cells rapidly produce acids and develop a transmembrane ph gradient ... | 1978 | 27785 |
| reduction of membrane potential, an immediate effect of colicin k. | colicin k causes a rapid and drastic reduction of the membrane potential of escherichia coli cells, as measured by the uptake of the lipophilic cation triphenylmethylphosphonium. the colicin causes no major changes in the ph gradient, as measured by the uptake of butyric acid. the decrease in membrane potential following addition of colicin k to the cells is a prompt response that parallels or precedes known physiological effects such as efflux of accumulated substrates. hence the loss of membra ... | 1978 | 27788 |
| homologous and cross-reactive precipitins in anti-pneumococcal sera raised in mules. | serial bleedings were obtained from two mules during prolonged immunization, one with type xxv the other with type viii pneumococcal vaccine. igga, iggb, iggc, igb, igg(t) and igm present among purified pn anti-xxv and pn anti-viii immunoglobulin isolated from various bleedings were identified by use of rabbit anti-equine heavy chain specific reagents. radioimmunodiffusion with 14c-labelled type xxv pneumococcal capsular polysaccharide and horse and donkey reagents with species specificity direc ... | 1978 | 28285 |
| specificity and regulation of gamma-aminobutyrate transport in escherichia coli. | a specific gamma-aminobutyrate (gaba) transport system in escherichia coli k-12 cells with a k(m) of 12 mum and a v(max) of 278 nmol/ml of intracellular water per min is described. membrane vesicles contained d-lactate-dependent activity of the system. mutants defective in gaba transport were isolated; they lost the ability to utilize gaba as a nitrogen source, although the activities of glutamate-succinylsemialdehyde transaminase (gsst) (ec 2.6.1.19) and succinylsemialdehyde dehydrogenase (ssdh ... | 1978 | 28310 |
| structural basis of the thermostability of monomeric malate synthase from a thermophilic bacillus. | malate synthases from a thermophilic bacillus and escherichia coli have been isolated in a high state of purity. molecular weights of these two proteins determined in the native state and after denaturation in sodium dodecyl sulfate-mercaptoethanol show that the enzymes are monomeric. this conclusion is supported, for the thermophile enzyme, by the result of an electrophoretic analysis of that protein after treatment with dimethylsuberimidate and denaturation. the thermophilic bacillus malate sy ... | 1978 | 28311 |
| biosynthesis in escherichia coli of sn-glycerol 3-phosphate, a precursor of phospholipid. kinetic characterization of wild type and feedback-resistant forms of the biosynthetic sn-glycerol-3-phosphate dehydrogenase. | homogeneous wild type and feedback-resistant forms of the biosynthetic sn-glycerol 3-phosphate (glycerol-p) dehydrogenase of escherichia coli (ec1.1.1.8) were subjected to two-substrate kinetic analysis. the kinetics of the nadph-dependent reduction of dihydroxyacetone phosphate (dihydroxyacetone-p) and of the nadp-dependent oxidation of glycerol-p indicate that these reactions proceed by a sequential mechanism. glycerol-p was a competitive inhibitor with respect to dihydroxyacetone-p for both e ... | 1978 | 28326 |
| allosteric regulation of monocyclic interconvertible enzyme cascade systems: use of escherichia coli glutamine synthetase as an experimental model. | the interconversion of escherichia coli glutamine synthetase l-glutamate:ammonia ligase (adp-forming), ec 6.3.1.2 between its adenylylated and unadenylylated forms has been used to verify the prediction derived from a theoretical analysis of the steady-state functions of a model for a monocyclic interconvertible enzyme cascade system stadtman, e. r. & chock, p. b. (1977) proc. natl. acad. sci. usa 74, 2761-2770. because glutamine and alpha-ketoglutarate are multifunctional effectors and because ... | 1978 | 28522 |
| effects of endotoxin on the pregnant baboon and fetus. | effects of e. coli endotoxin upon uterine activity and maternal and fetal condition were studied in four pregnant baboons and their fetuses. uterine activity increased significantly following administration of endotoxin to the mother. endotoxin also produced maternal circulatory collapse, severe acidosis, and profound fetal asphyxia resulting in death. death also occurred in three of the four mothers within 24 hours without amelioration of their conditions. | 1978 | 28672 |
| chloramphenicol acetyltransferase of bacteroides fragilis. | chloramphenicol-resistant strains of bacteroides fragilis (minimum inhibitory concentration, 12.5 mug/ml) were isolated from a stool specimen which contained multiply resistant escherichia coli. the enzyme responsible for resistance, chloramphenicol acetyltransferase, was produced constitutively by these strains; the specific activity was 10-fold lower than that of the e. coli enzymes. similar activity was not detected in susceptible b. fragilis strains, nor could it be induced by growth in the ... | 1978 | 28690 |
| piperacillin: in vitro evaluation. | the in vitro activity of a new semisynthetic penicillin, piperacillin, was determined against 577 clinical isolates of gram-positive cocci and gram-negative bacilli. a concentration of 12.5 mug/ml inhibited 92% of isolates of pseudomonas aeruginosa, 82% of serratia marcescens, 73% of escherichia coli, 61% of klebsiella spp., and 42% of enterobacter spp. most proteus spp. were extremely susceptible; over 85% were inhibited by 0.10 mug/ml. piperacillin failed to inhibit the growth of gram-negative ... | 1978 | 28694 |
| research of the soluble microbial substances in organic fluids for the rapid diagnosis of some infections and particularly of bacterial meningitis (author's transl). | a number of immunological and non-immunological techniques have been recently used to detect soluble microbial substances in body fluids of patients with acute meningitis, bacteremia, and lobar pneumonia. by the immunological methods capsular highly polymerized polisaccharide group- or type-specific antigens of the most common c. n. s. pathogens (n. meningitidis a, b, and c; str. pneumoniae, h. influenzae type b, e. coli k1, mucoid pseudomonas, cryptococcus neoformans) can be detected and quanti ... | 1977 | 28697 |
| the enzymes of proline biosynthesis in escherichia coli. their molecular weights and the problem of enzyme aggregation. | 1. by using bio-gel a1.5m and sephadex g-150 columns, crude cell-free extracts of escherichia coli were fractionated to demonstrate the existence of a proline-biosynthetic aggregate. 2. sephadex g-150 resolves two glutamyl kinases that are inhibited by proline, with mol.wts. of 125000 and 38000, the reactions of which are mg2+-dependent. the heavier species is more sensitive to inhibition by proline. 3. gamma-glutamyl phosphate reductase and 1-pyrroline-5-carboxylate reductase (ec 1.5.1.2) have ... | 1978 | 28732 |
| purification and immunochemical characterization of malate synthase from euglena gracilis. | malate synthase (ec 4.1.3.2) from dark-grown euglena gracilis was purified to homogeneity by the criterion of polyacrylamide-gel electrophoresis. the enzyme was released from acetate-grown cells by treatment with ultrasonic waves and purified from broken-cell suspensions by high-speed centrifugation and (nh4)2so4 fractionation, followed by gel-filtration on sepharose 6b. the final enzyme preparation was purified 190-fold compared with the crude extract. the mol.wt. of the enzyme was about 350000 ... | 1978 | 28738 |
| threonine inhibition of the aspartokinase--homoserine dehydrogenase i of escherichia coli. threonine binding studies. | both activities of the aspartokinase--homoserine i (ak-hsd) of escherichia coli are inhibited by threonine. careful threonine binding studies have now been done which have allowed us to distinguish the various effects of threonine on the enzyme. the ultrafiltration technique of h. paulus ((1969) anal. biochem. 32, 101) for measuring ligand binding was shown to be comparable with equilibrium dialysis techniques. reduction in error by utilization of this procedure enabled us to obtain evidence for ... | 1978 | 28750 |
| threonine inhibition of the aspartokinase--homoserine dehydrogenase i of escherichia coli. stopped-flow kinetics and the cooperativity of inhibition of the homoserine dehydrogenase activity. | | 1978 | 28751 |
| threonine inhibition of the aspartokinase--homoserine dehydrogenase i of escherichia coli. a slow transient and cooperativity of inhibition of the aspartokinase activity. | | 1978 | 28752 |
| distance determinations between the metal ion sites of escherichia coli glutamine synthetase by electron paramagnetic resonance using cr(iii)--nucleotides as paramagnetic substrate analogues. | | 1978 | 28753 |
| zinc stoichiometry in escherichia coli alkaline phosphatase. studies by 31p nmr and ion-exchange chromatography. | 31p nuclear magnetic resonance spectra and enzymatic activities are compared for alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), ec 3.1.3.1) species with different zinc contents. the enzyme containing two zn2+ per protein dimer exists in two forms; one, prepared by dialysis of native enzyme, has full enzymatic activity and a 31p magnetic resonance spectrum similar to but distinguishable from that of the native enzyme containing four or more zn2+. the other fo ... | 1978 | 28775 |
| a spectral probe near the subunit catalytic site of glutamine synthetase from escherichia coli. reduced pyridoxal 5'-phosphate.enzyme complexes. | in order to label phosphate binding sites, unadenylylated glutamine synthetase from escherichia coli has been pyridoxylated by reacting the enzyme with pyridoxal 5'-phosphate followed by reduction of the schiff base with nabh4. a complete loss in mg2+-supported activity is associated with the incorporation of 3 eq of pyridoxal-p/subunit of the dodecamer. at this extent of modification, however, the pyridoxylated enzyme exhibits substantial mn2+-supported activity (with increased km values for at ... | 1978 | 29046 |
| r-factor mediated dihydrofolate reductases which confer trimethoprim resistance. | six different r-factors conferring trimethoprim resistance had been isolated from a variety of sources. the trimethoprim-resistant dihydrofolate reductases (ec 1.5.1.3) from strains containing these r-factors were purified by ammonium sulphate precipitation and deae-cellulose ion-exchange chromatography. the enzymes showed no significant differences in molecular weight, ph profile, substrate profile, heat sensitivity, inhibition profile and michaelis-menten kinetics. there was, however, consider ... | 1978 | 29076 |
| microcalorimetric study of the effects of cephalexin and cephaloridin on escherichia coli and staphylococcus aureus. | the kinetics of the antibacterial actions of cephalexin and cephaloridin against a strain of escherichia coli and a strain of staphylococcus aureus were studied by a flow microcalorimeter. the heat production was related to the number of viable organisms (cfu ml-1), the ph, the optical density of the culture medium (od540), and the morphology of the antibiotic-exposed bacteria. no heat effects could be registered when the number of cfu was below 10(4) ml-1. the addition of cephalexin, 2.5 microg ... | 1978 | 29439 |
| evaluation of the counterimmunoelectrophoretic (cie) procedure in a clinical laboratory setting. | the counterimmunoelectrophoretic (cie) procedure was evaluated under clinical laboratory conditions to determine its validity and comparability with culture methods. the procedure was further evaluated to determine applicability to a variety of clinical samples. an inexpensive set-up was developed to utilize the cie procedure at bench level. results indicated the procedure to be sensitive in detecting haemophilus influenzae, type b, and neisseria meningitidis (meningococcus), group b. the proced ... | 1978 | 29483 |
| use of amp specific antibodies to differentiate between adenylylated and unadenylylated e. coli glutamine synthetase. | | 1978 | 29611 |
| coupling between h+ entry and atp formation in escherichia coli. | | 1978 | 29634 |
| proton translocation associated with anaerobic transhydrogenation from glycerol 3-phosphate to fumarate in escherichia coli. | | 1978 | 29636 |
| cation/proton antiport systems in escherichia coli. | | 1978 | 29637 |
| d-amino acids of the amino acid pool and occurrence of racemase and d-amino acid oxidase activities in escherichia coli b. | less than 20% of the amino acid content of the amino acid pool of escherichia coli b exists in the d-form. alanine, glutamic acid, and valine were shown by gas- chromatography to be partially in the d-form. only d-alanine was formed by racemization in the crude extract of this organism. alanine racemase was easily released from the membranes or vesicles but d-alanine oxidase activity remained firmly bound to the membrane. most protein amino acids stimulated proline uptake into the vesicles, and ... | 1978 | 29829 |
| inability of selected lactobacilli to inhibit the heat-labile or heat-stable enterotoxin effects of escherichia coli b7a. | | 1978 | 29883 |
| functional lac carrier protein in cytoplasmic membrane vesicles isolated from escherichia coli: temperature and ph dependence of dansyl-galactoside binding. | 6'-(n-dansyl)aminohexyl-1-thio-beta-d-galactopyranoside binds specifically to the lac carrier protein in cytoplasmic membrane vesicles isolated from escherichia coli. binding can be induced by substrate oxidation (generation of an electrochemical gradient of protons), by potassium efflux in the presence of valinomycin (generation of a potassium diffusion potential), and by passive, carrier-mediated lactose efflux. we show that in all three cases the number of binding sites is temperature depende ... | 1978 | 30084 |
| partial purification and properties of ctp:phosphatidic acid cytidylyltransferase from membranes of escherichia coli. | the cytosine liponucleotides cdp-diglyceride and dcdp-diglyceride are key intermediates in phospholipid biosynthesis in escherichia coli (c. r. h. raetz and e. p. kennedy, j. biol. chem. 248:1098--1105, 1973). the enzyme responsible for their synthesis, ctp:phosphatidic acid cytidylytransferase, was solubilized from the cell envelope by a differential extraction procedure involving the detergent digitonin and was purified about 70-fold (relative to cell-free extracts) in the presence of detergen ... | 1978 | 30751 |
| presence of escherichia coli of a deaminase and a reductase involved in biosynthesis of riboflavin. | two enzymes have been partially purified from extracts of escherchia coli b which together catalyze the conversion of the product of the action of gtp cyclohydrolase ii, 2,5-diamino-6-oxy-4-(5'-phosphoribosylamine)pyrimidine, to 5-amino-2,6-dioxy-4-(5'-phosphoribitylamine)pyrimidine. these two compounds are currently thought to be intermediates in the biosynthesis of riboflavin. the enzymatic conversion occurs in two steps. the product of the action of gtp cyclohydrolase ii first undergoes hydro ... | 1978 | 30756 |
| partial reactions of aminoacyl-trna synthetases as functions of ph. | the effect of ph on the properties of the partial reactions of arginyl-trna synthetase of e. coli has been investigated. v max of pyrophosphorolysis of arginyl adenylate has a ph optimum at ph 6.1, whereas v max of the transfer of arginine to trna has a ph optimum of 8.2. these values correlate with the ph optima of the atp:ppi exchange and the overall esterification reaction, respectively. only the pyrophosphorolysis reaction requires a divalent cation; transfer proceeds in the presence of edta ... | 1978 | 30773 |
| transport capacity, alkaline phosphatase activity and protein content of glutaraldehyde-treated cell forms of escherichia coli. | studies on the comparative transport capacity of various cell forms of escherichia coli suggest that glutaraldehyde acts only in the outer regions of the cell envelope and to such an extent that transport of alpha-aminoisobutyric acid is reduced by 50%. alkaline phosphatase activity in whole cells was severely impaired in the presence of alkaline glutaraldehyde and in nacl-washed cells both acid and alkaline glutaraldehyde (0.01%) caused approximately 80-90% reduction in enzyme activity in 10 mi ... | 1977 | 30880 |
| [dna synthesis and degradation in the cells of bacillus stearothermophilus]. | atp-dependent and atp-independent synthesis of dna was studied on nucleotide-permeable cells of bacillus stearothermophilus. the effect of temperature, ph, ionic strength, and bivalent metal ions on both types of dna synthesis was investigated as well as their susceptibility to an sh-blocking agent. the level of atp-independent synthesis of dna in the cells of bac. stearothermophilus was found to be ten times higher than that in e. coli. in the semipermeable cells of bac. stearothermophilus, 90% ... | 1978 | 30883 |
| [chemical parameters in coastal waters in correlation with microbiological parameters (author's transl)]. | nearly 4600 samples of coastal water from the baltic sea were characterized by microbiological parameters as well as by ph, ammonium, nitrite, nitrate, phosphate, and oxidizability by permanganate. correlation of e. coli with chemical parameters varies strongly according to parameter, region, and season. sanitary assessments can only be based on microbiological findings.--as regards eutrophication, we should expect special and more comprehensive chemical test programmes to give us substantial kn ... | 1978 | 31044 |
| studies of relationship among terrestrial pseudomonas, alcaligenes, and enterobacteria by an immunological comparison of glutamine synthetase. | antibody to purified glutamine synthetase from escherichia coli was prepared and used for an immunological comparison of glutamine synthetases from species of salmonella, citrobacter, enterobacter, serratia, proteus, erwinia, aeromonas, pseudomonas, acinetobacter, xanthomonas, alcaligenes, and paracoccus. the results of ouchterlony double diffusion experiments and quantitative microcomplement fixation studies indicated that the amino acid sequence of this enzyme was highly conserved in different ... | 1978 | 31146 |
| the polymorphic phase behaviour of phosphatidylethanolamines of natural and synthetic origin. a 31p nmr study. | 1. the polymorphic phase behaviour of aqueous dispersions of phosphatidylethanolamines isolated from human erythrocytes, hen egg yolk and escherichia coli have been investigated employing 31p nmr techniques. all species exhibit well defined, reversible bilayer to hexagonal (h11) phase transitions as the temperature is increased. the temperatures at which these transition take place (10, 25--30 and 55--60 degrees c for erythrocyte, egg yolk and e. coli phosphatidylethanolamine, respectively) are ... | 1978 | 31173 |
| stereoelectronic factors in the binding of substrate analogues and inhibitors to purine nucleoside phosphorylase isolated from human erythrocytes. | several aspects of the stereoelectronic requirements of substrates of human erythrocytic purine nucleoside phosphorylase (e.c. 2.4.2.1) were elucidated providing the following information: (a) the n1 position cannot have a nonhydrogen substituent; (b) the 5'-oh group must be present for catalytic activity to be exhibited but is not an essential functional group for inhibitory action to be observed; (c) on the c8 position groups larger than -nh2 or -br cannot be accommodated; (d) the syn-glycosyl ... | 1978 | 31484 |
| phosphorus-31 nmr studies of e. coli ribosomes. | phosphorus-31 nuclear magnetic resonance spectra, relaxation times and nuclear overhauser (noe) enhancement have been measured for e. coli ribosomes, subunits and rrna. noe and t1 experiments reveal that the phosphorus relaxation in this organelle is largely dipolar in origin. moreover these results imply the presence of internal motion within the rna chain with a correlation time of about 3-5 x 10(-9) sec. in all cases the predominant resonance is centered at about -1.5 ppm (relative to 85% h3p ... | 1978 | 31604 |
| [changes in the number of escherichia coli, streptococcus faecalis and streptococcus faecium stored in physiological solution at a temperature of 20 degrees c]. | | 1977 | 31606 |
| the use of bacteria for the functional characterization of human lymphocyte subpopulations in various lymphoid organs. | in a haemolytic plaque assay staphylococcal strain cowan 1 was shown to induce polyclonal antibody secretion in human blood lymphocytes, whereas haemophilus influenzae and escherichia coli gave low responses. diplococcus pneumoniae and haemolytic streptococci generally did not activate blood cells. all five bacteria could activate spleen, tonsil and adenoid cells both to polyclonal ig secretion and increased dna synthesis. thus blood cell reactivity does not necessarily reflect the response patt ... | 1978 | 31677 |
| the extraction of guanosine 5'-diphosphate, 3'-diphosphate (ppgpp) from escherichia coli using low ph reagents: a reevaluation. | | 1978 | 31874 |
| synthesis of quinolinate from d-aspartate in the mammalian liver-escherichia coli quinolinate synthetase system. | | 1978 | 31876 |
| subunit dissociation in the allosteric regulation of glycerol kinase from escherichia coli. 3. role in desensitization. | the mechanism of desensitization of glycerol kinase to allosteric inhibition by fructose 1,6-bisphosphate caused by salt, urea, and high ph has been examined in the light of the model proposed in an earlier paper [de riel, j. k., and paulus h. (1978), biochemistry 17] relating subunit dissociation and ligand binding. kcl (0.4 m) causes a tenfold decrease in the affinity of tetrameric glycerol kinase for fructose, 1,6-bisphosphate but has no significant effect on the dissociation process itself. ... | 1978 | 31903 |
| acyl carrier protein from escherichia coli: characterization by proton and fluorine-19 nuclear magnetic resonance and evidence for restricted mobility of the fatty acid chain in tetradecanoyl-acyl-carrier protein. | the acyl-carrier protein (acp) of escherichia coli is a protein of molecular weight 8847 with a 4'-phosphopanthetheine prosthetic group. acp functions (via the sh of the prosthetic group) as a coenzyme in the synthesis of fatty acids and complex lipids. we report proton nuclear magnetic resonance (nmr) studies of the structure of acp under various experimental conditions. the motion of the fatty acyl chain of acyl-acp has been investigated by 19fnmr studies of difluorotetradecanoyl-acp. 31pnmr s ... | 1978 | 31907 |
| prospects for the prevention of bacterial meningitis with polysaccharide vaccines. | most suppurative infections of the meninges are caused by five bacterial species: escherichia coli, haemophilus influenzae type b, streptococcus pneumoniae, neisseria meningitidis, and group b streptococcus. the immune response of adults to pneumococcal capsular polysaccharides has been studied in great detail and their responses to meningococcal and h. influenzae type b capsular polysaccharides are quite similar. immune responses of adults to e. coli and group b streptococcal antigens are disap ... | 1978 | 31985 |
| interactions between amethocaine (tetracaine) and non-growing cultures of escherichia coli. | | 1979 | 32365 |
| localization of the site of adenylylation of glutamine synthetase by electron microscopy of an enzyme-antibody complex. | antibodies to the nucleosidel,n(6)-ethenoadenosine have been used to localize the site of adenylylation of the glutamine synthetase [l-glutamate:ammonia ligase (adp-forming), ec 6.3.1.2] of escherichia coli. antibodies were induced in rabbits by injection of a bovine albumin-ethenoadenosine conjugate. the resulting antisera strongly bound ethenoadenosine, its 5'-nucleotide, or protein conjugates of the nucleoside; little or no crossreaction was seen to adenosine, amp, or the protein carrier. eth ... | 1978 | 32536 |
| mechanisms of action of cholera and escherichia coli enterotoxins. | current information is reviewed on the mechanism of secretion in small intestine, including how it is altered by cyclic 3',5'-adenosine monophosphate and on the structures and properties of cholera and both heat-labile and heat-stable escherichia coli enterotoxins. two separate active ion transport processes are altered by cyclic 3',5'-adenosine monophosphate: 1) coupled absorption of nacl is inhibited in villus cells and 2) active anion secretion is stimulated, probably in crypt cells. cholera ... | 1979 | 32766 |
| transcription of rat liver deoxyribonucleic acid in vitro at low ionic strength. | 1. when rna polymerase is in excess over dna, the single-stranded breaks of dna can be recognized as initiation sites for the ezyme. on the other hand stabel initiation complexes (resistant to inhibition by heparin) are the most abundant under these conditions. the formation of these complexes needs double-stranded dna. it seems that rna sequences rich in cytidine are preferentially synthesized; since rat liver dna is a + t-rich, the transcription thus appears not to be random with respect to th ... | 1978 | 32873 |
| kinetic studies of 18o exchange from inorganic phosphate catalyzed by mg2+-activated unadenylylated glutamine synthetase (e. coli w). | | 1978 | 32887 |
| refolding and reactivation of escherichia coli tryptophan synthase beta2 subunit after inactivation and dissociation in guanidine hydrochloride at acidic ph. | | 1978 | 33046 |
| studies on polypeptide-chain-elongation factors from an extreme thermophile, thermus thermophilus hb8. 3. molecular properties. | molecular properties of the polypeptide chain elongation factors from thermus thermophilus hb8 have been investigated and compared with those from escherichia coli. 1. as expected, the factors purified from t. thermophilus were exceedingly heat-stable. even free ef-tu not complexed with gdp was stable after heating for 5 min at 60 degrees c. 2. gdp binding activity of t. thermophilus ef-tu was also stable in various protein denaturants, such as 5.5 m urea, 1.5 m guanidine-hcl, and 4 m licl. 3. ... | 1978 | 33049 |
| oxidative phosphorylation and proton translocation in a lipoate-deficient mutant of escherichia coli. | | 1979 | 33067 |
| purification and properties of an inducible beta-galactosidase isolated from the yeast kluyveromyces lactis. | beta-galactosidase (ec 3.2.1.32) was purified 80-fold from the yeast kluyveromyces lactis induced for this enzyme by growth on lactose. when the purified enzyme was subjected to electrophoresis on an acrylamide gel in the presence of sodium dodecyl sulfate, one protein with an apparent molecular weight of 135,000 was observed. the enzyme has a sedimentation coefficient of 9.6s. this beta-galactosidase and the one from escherichia coli are not antigenically related. maximal enzyme activity requir ... | 1979 | 33153 |
| transport of nicotinamide adenine dinucleotide in an unc mutant of escherichia coli. | the presence and some properties of an nad+ transport system were examined in pa5, a mg, ca-atpase [ec 3.6.1.3]-defective mutant strain of escherichia coli w2252. nad+ uptake was stimulated by exogenous energy sources and dependent on external substrate concentrations with an apparent km of about 25 micrometer. most of the radioactivity from [14c]-nad+ accumulated in the cells was identified as nad+. [14c]nad+ uptake was competively inhibited by unlabeled nad+, nadp+, nmn+ or nicotinamide. simil ... | 1978 | 33159 |
| evidence for multiple electronic forms of two-electron-reduced lipoamide dehydrogenase from escherichia coli. | results are presented which demonstrate that the 2-electron-reduced lipoamide dehydrogenase (ec 1.6.4.3) from escherichia coli is a mixture of species. in catalysis, this enzyme cycles between the oxidized and the 2-electron-reduced forms. three spectrally distinct species are indicated in the ph range 5.8 to 8.0 from measurements of the fluorescence and visible spectra during dithionite titration. these have the following properties. 1) a fluorescent form where the fad is oxidized and the activ ... | 1979 | 33177 |