| limited hydrolysis of trna by phosphodiesterase. | digestion of trna by electrophoretically pure phosphodiesterase is limited to a short sequence of nucleotides at the 3'-terminus. on the average, four percent of all nucleotides can be released from trna. the optimum mg2 concentration is 10mm and the optimum ph 9.2. the mode of action is a random attack by the enzyme on the substrate. the terminal amp is completely removed at 15 degrees c after short incubation; about 400 mol of amp were removed per min by 1 mol of enzyme. the following cmp resi ... | 1975 | 296 |
| novel type of murein transglycosylase in escherichia coli. | the purification and properties of a novel type of murein transglycosylase from escherichia coli are described. the purified enzyme appears as a single band on sodium dodecyl sulfate-polyacrylamide gels and has an apparent molecular weight of approximately 65,000 as estimated by gel filtration and gel electrophoresis. it degrades pure murein sacculi from e. coli almost completely into low-molecular-weight products. the two prominent muropeptide fragments in the digest are the disaccharide-tripep ... | 1975 | 357 |
| phospholipase d activity of gram-negative bacteria. | a phospholipase hydrolyzing cardiolipin to phosphatidic acid and phosphatidyl glycerol was characterized in gram-negative bacteria but was absent in preparations of gram-positive bacteria, saccharomyces cerevisiae, and rat liver mitochondria. in cell-free extracts of escherichia coli, salmonella typhimurium, proteus vulgaris, and pseudomonase aeruginosa, this cardiolipin-hydrolyzing enzyme had similar ph and mg2+ requirements and displayed a specificity which excluded phosphatidyl glycerol and p ... | 1975 | 360 |
| expression of the hut operons of salmonella typhimurium in klebsiella aerogenes and in escherichia coli. | the normal hut (histidine utilization) operons, as well as those with mutations affecting the regulation of their expression, of salmonella typhimurium were introduced on an f' episome into cells of s. typhimurium and klebsiella aerogenes whose chromosomal hut genes had been deleted and into cells of escherichia coli, whose chromosome does not carry hut genes. the episomal hut operons respond in a manner very similar to induction and catabolite repression in all three organisms. the small differ ... | 1975 | 362 |
| bacteriophage t4 baseplate components. ii. binding and location of bacteriophage-induced dihydrofolate reductase. | the location of t4d phage-induced dihydrofolate reductase (dfr) has been determined in intact and incomplete phage particles. it has been found that phage mutants inducing a temperature-sensitive dfr (dfrts) procude heat-labile phage particles. the structural dfr produced by these ts mutants was shown to assume different configurations depending on the temperature at which the phage is assembled. morphogenesis of incomplete phage particles lacking the gene 11 protein on their baseplates was foun ... | 1975 | 516 |
| phix174 dna-dependent dna synthesis in vitro: requirement for p1 ban protein in dnab mutant extracts of escherichia coli. | ammonium sulfate fractionation of crude extracts of e. coli yields a soluble enzyme fraction (about 25-fold purification) that catalyzes the conversion of phix174 single-stranded dna to duplex dna. the reaction is rifampicin-resistant, requires single-stranded dna, mg++, deoxynucleoside triphosphates, and atp, and is stimulated by kcl. such soluble enzyme fractions were prepared from e. coli strains carrying the prophage mutant p1bac, in which the viral dnab analog (ban) protein is expressed con ... | 1975 | 670 |
| disorders of micturition in bacterial prostatitis. | measurements of urinary flow rate were performed in 16 patients with established prostatitis before and after a course of antimicrobial therapy. before treatment the maximum flow rates were poor with abnormal flow curves and significant improvement in voiding characteristics were observed with treatment (p less than 0.01). a preliminary electrophysiological (emg) study of sphincter activity suggested that the obstruction to the flow of urine was at least in part due to failure of the external sp ... | 1975 | 681 |
| separation of low molecular weight rna by polyacrylamide gel electrophoresis. | | 1975 | 925 |
| trypsin-catalyzed activation of aspartase. | | 1975 | 1021 |
| utilization of ammonia for tryptophan synthesis. | | 1975 | 1034 |
| biochemical function and homeostasis: the payoff of the genetic program. | | 1975 | 893 |
| the cathode bound group antigen of dysentery-provoking escherichieae (author's transl). | antigens from disrupted cells of dysentery-provoking and of non-enteropathogenic escherichieae were submitted to immunoelectrophoresis on cellulose acetate stripes at ph 8.0. among 6 immune sera produced for this purpose by immunizing rabbits against desintegrated dysentery bacteria, only one contained a precipitine reacting with an antigen similar to the "generic antigen" of belaya. this - at ph 8.0 - cathode-bound group antigen (kga) could not only be found in virulent but also in 5 attenuated ... | 1975 | 873 |
| ubiquinone-mediated coupling of nadh dehydrogenase to active transport in membrane vesicles from escherichia coli. | addition of ubiquinone-1 to e. coli ml 308-225 membrane vesicles dramatically increases coupling between nadh oxidation and active transport such that initial rates and steady-state levels of lactose and amino-acid accumulation are comparable to those observed during d-lactate oxidation. similar but less dramatic effects are observed with the quinone and succinate or l-lactate. in the presence of nadh and ubiquinone-1, the vesicles also generate a membrane potential (interior negative) that is s ... | 1975 | 672 |
| identification of the 30 s protein adjacent to peptidyl transferase catalytic center of escherichia coli ribosomes. | iodoacetylphenylalanyl-trnaphe was used as an affinity label to localize the ribosomal components involved in the peptidyl transferase catalytic center of escherichia coli ribosomes. when labeling was carried out at ph 5.0, the affinity label could specifically label the ribosomal components which comprise the catalytic center. analysis of ribosomal proteins which had reacted with the affinity label revealed that a 30 s subunit protein, s 20, was located at or near to the ribosomal binding site ... | 1975 | 611 |
| effect of inorganic phosphate on acridine inhibition and plasmid curing in escherichia coli. | some mutants and stock strains of escherichia coli k12 were sensitive to acriflavine in the presence of inorganic phosphate but were resistant to acriflavine in its absence. they mutated spontaneously to resistance to acriflavine plus phosphate. the synergistic effect of phosphate on acriflavine sensitivity was increased at high ph values. genetic analysis suggested that the mutations occurred in the gene acra. electron microscopic observation suggested that the presence of acriflavine plus phos ... | 1975 | 466 |
| inhibitory effects of antihistamines and antiserotonins on the bone marrow reactions produced by escherichia coli endotoxin in mice. | the bone marrow reactions (that is, decrease of nucleated cell counts and increase of red blood cell counts) of mouse bone were observed 1 hr after injection of endotoxin and peaked after 18 hr. these reactions were significantly inhibited when diphenhydramine, promethazine (antihistamines), chlorpromazine (antiserotonin), or cyproheptadine (antihistamine and antiserotonin) was given 30 min before endotoxin. such bone marrow reactions were also induced with histamine or serotonin and peaked 1 hr ... | 1975 | 442 |
| sn-glycerol-3-phosphate acyltransferase activity in particulate preparations from anaerobic, light-grown cells of rhodopseudomonas spheroides. involvement of acyl thiolester derivatives of acyl carrier protein in the synthesis of complex lipids. | crude particulate preparations obtained from anaerobic, light-grown cells of rhodopseudomonas spheroides have been shown to possess a significant level of sn-glycerol-3-phosphate acyltransferase (ec 2.3.1.15) activity. in contrast to the enzyme from escherichia coli, the r. spheroides glycerophosphate acyltransferase has a high specificity for acyl thiolester derivatives of acyl carrier protein (acp) as acyl donors for the reaction. only limited , nonlinear glycerophosphate incorporation into li ... | 1975 | 387 |
| nitrofurazone-reducing enzymes in e. coli and their role in drug activation in vivo. | earlier work showed that escherichia coli contains at least two enzymes which reduce nitrofurazone and other nitrofuran derivatives. one of these enzymes is lacking in some nitrofurazone-resistant mutant strains. we now report that there are three separable nitrofuran reductases in this organism: reductase i (mol. wt. approximately 50 000, insensitive to o2), reductase iia (mol. wt. approximately 120 000, inhibited by oxygen), reductase iib (mol. wt. approximately 700 000, inhibited by o2). unst ... | 1975 | 136 |
| hybrids of chemical derivatives of escherichia coli alkaline phosphatase. | the activities of hybrid dimers of alkaline phosphatase containing two chemically modified subunits have been investigated. one hybrid species was prepared by dissociation and reconstitution of a mixture of two variants produced by chemical modification of the native enzyme with succinic anhydride and tetranitromethane, respectively. the succinyl-nitrotyrosyl hybrid was separated from the other members of the hybrid set by deae-sephadex chromatography and then converted to a succinyl-aminotyrosy ... | 1975 | 86 |
| evidence of the involvement of a 50s ribosomal protein in several active sites. | the functional role of the bacillus stearothermophilus 50s ribosomal protein b-l3 (probably homologous to the escherichia coli protein l2) was examined by chemical modification. the complex b-l3-23s rna was photooxidized in the presence of rose bengal and the modified protein incorporated by reconstitution into 50s ribosomal subunits containing all other unmodified components. particles containing photooxidized b-l3 are defective in several functional assays, including (1) poly(u)-directed poly( ... | 1975 | 52 |
| purification and properties of escherichia coli dihydrofolate reductase. | dihydrofolate reductase has been purified 40-fold to apparent homogeneity from a trimethoprim-resistant strain of escherichia coli (rt 500) using a procedure that includes methotrexate affinity column chromatography. determinations of the molecular weight of the enzyme based on its amino acid composition, sedimentation velocity, and sodium dodecyl sulfate gel electrophoresis gave values of 17680, 17470 and 18300, respectively. an aggregated form of the enzyme with a low specific activity can be ... | 1975 | 46 |
| bovine liver dihydrofolate reductase: purification and properties of the enzyme. | a purification procedure is reported for obtaining bovine liver dihydrofolate reductase in high yield and amounts of 100-200 mg. a key step in the procedure is the use of an affinity gel prepared by coupling pteroyl-l-lysine to sepharose. the purified reductase has a specific activity of about 100 units/mg and is homogeneous as judged by analytical ultracentrifugation, polyacrylamide gel electrophoresis, and titration with methotrexate. the products of the first step of edman degradation indicat ... | 1975 | 45 |
| poly(8-aminoguanylic acid): formation of ordered self-structures and interaction with poly(cytidylic acid). | poly(8-aminoguanylic acid) has in neutral solution a novel ordered structure of high stability. the 8-amino group permits formation of three hydrogen bonds between two residues along the "top", or long axis, of the purines. the usual hydrogen bonding protons and watson-crick pairing sites are not involved in the association. the bonding scheme has a twofold rotation axis and is hemiprotonated at n(7). poly(8nh2g) is converted by alkaline titration (pk = 9.7) to a quite different ordered structur ... | 1975 | 37 |
| microbiological study of gentamiycin. | gentamycin prepared at the all-union research institute of antibiotics did not differ by its antibacterial spectrum and the activity level from gentamycin samples from other countries. by its activity against clinical strains of ps. aeruginosa gentamycin was somewhat inferior than polymyxin but much more superior than carbenicillin. an agar-diffusion method using bac. pumilus ntcc 8241 as the test microbe was developed for determination of gentamycin activity. the gentamycin sulfate complex and ... | 1975 | 2095 |
| use of lincomycin, methicillin and ristomycin in the nutrient media for isolating pathogenic intestinal microorganisms. | elective-differentiating solid nutrient media for simultaneous isolation of vibrioes, salmonella and shigella were developed. antibiotics active against grampostive microflora and dry bile salts inhibiting the growth of proteus were used as the inhibitors of the growth of the accompanying microflora. the medium was lincomycin and the bile salts may be prepared in a dry form. | 1975 | 2096 |
| bacterial and fungal growth in total parenteral nutrition solutions,. | the most serious complication of prolonged intravenous infusion of hypertonic dextrose and amino acids is infection. frequently, the etiology is fungal rather than bacterial. previous authors have suggested that bacterial survival and growth in the solutions is suppressed by (a) high dextrose concentration, (b) high osmolality, or (c) low ph. this paper presents evidence that proposals (a) and (b) are untenable and (c) is only partly responsible. we call attention to the presence of a factor tha ... | 1975 | 2102 |
| arginine decarboxylase from a pseudomonas species. | an arginine decarboxylase has been isolated from a pseudomonas species. the enzyme is constitutive and did not appear to be repressed by a variety of carbon sources. after an approximately 40-fold purification, the enzyme appeared more similar in its properties to the escherichia coli biosynthetic arginine decarboxylase than to the e. coli inducible (biodegradative) enzyme. the pseudomonas arginine decarboxylase exhibited a ph optimum of 8.1 and an absolute requirement of mg2+ and pyridoxal phos ... | 1976 | 1382 |
| preparations and properties of ribonucleic acid polymerase from acinetobacter calcoaceticus. | deoxyribonucleic acid (dna)-dependent ribonucleic acid (rna) polymerase (ec 2.7.7.6) from acinetobacter calcoaceticus was purified to apparent homogeneity and its properties were compared with those of the escherichia coli b enzyme. the molecular weights of the two native active enzymes as well as their alpha and beta subunits appeared to be similar. no subunit corresponding to that of sigma from e. coli was found, and furthermore no separation between the beta subunits could be detected by gel ... | 1976 | 1380 |
| purification and properties of beta-n-acetylglucosaminidase from escherichia coli. | beta-n-acetylglucosaminidase (ec 3.2.1.30) has been purified from escherichia coli k-12 to near homogeneity based on polyacrylamide gel electrophoresis in both 0.5% sodium dodecyl sulfate and in 6 m urea at ph 8.5. the purified enzyme shows a ph optimum of 7.7 and the km for p-nitrophenyl-beta-d-2-acetamido-2-deoxyglucopyranoside is 0.43 mm. the molecular weight of this enzyme, determined by both sephadex gel filtration and by sodium dodecyl sulfate gel electrophoresis, is equivalent to 36,000. ... | 1976 | 1377 |
| microcalorimetric study of the anaerobic growth of escherichia coli: measurements of the affinity of whole cells for various energy substrates. | microcalorimetry has been used to determine the affinity of whole cells of escherichia coli for glucose, galactose, fructose, and lactose. anaerobic growth thermograms were analyzed, and the km and vmax values for these energy substrates were measured at ph 7.8. results obtained with this technique using various organisms growing anaerobically on different sugars are compared. this comparison shows that in practically all cases the cellular rate of catabolic activity is a hyperbolic function of ... | 1976 | 1373 |
| microcalorimetric study of the anaerobic growth of escherichia coli: growth thermograms in a synthetic medium. | a microcalorimetric technique was used for studying the growth of escherichia coli during anaerobiosis. the growth thermograms obtained are complex and the shape of curves is dependent on the hydrogen lyase activity of the cells. fermentation balances are given for different culture conditions, and simple growth thermograms are obtained when the hydrogen lyase activity is inhibitied. | 1976 | 1371 |
| purification and properties of a periplasmic aminoendopeptidase from escherichia coli. | a periplasmic aminoendopeptidase from escherichia coli has been purified to hemogeneity. it is a monomer of molecular weight 45000 and containing one -- sh group that is necessary for catalytic activity. the study of its substrate specificity indicated that the enzyme has both aminopeptidase and endopeptidase activity. the ph optimum for l-alanine p-nitroanilide hydrolysis is between 7 and 7.5 and that for 125i-labeled casein proteolysis between 7.3 and 7.6. the activation energy for the hydroly ... | 1975 | 1271 |
| effect of ph and pyridoxal phosphate on the quaternary structure of e. coli glutamate decarboxylase. | | 1975 | 1215 |
| l-alphas, 5s-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (nsc-163501): a new amino acid antibiotic with the properties of an antagonist of l-glutamine. | l-alphas,5s-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (nsc-163501), an antibiotic elaborated by streptomyces sviceus, has been shown to be a powerful inhibitor of many mammalian and bacterial reactions involving the transfer of nitrogen from the gamma-carboxamide of l-glutamine. thus, the utilization of l-glutamine for the synthesis of carbamyl phosphate, l-asparagine, guanosine-5'-monophosphate, cytidine-5'-triphosphate, n-formylglycinamidine ribonucleotide, nad, glucosamine-6-pho ... | 1975 | 1147 |
| intermediate plateaux in kinetics of the reaction catalyzed by biodegradative l-threonine dehydratase from escherichia coli. | it has been shown that for the reaction catalyzed by "biodegradative" l-threonine dehydratase from e. coli strains k-12 and 980 in 0.5 m phosphate-carbonate buffer, ph 8.4 and ph 9.5, the plots of initial reaction rate (v) versus the initial substrate concentration (s0 are characterized by several inflection points, i. e. an intermediate plateau. the plot of v versus the allosteric activator (amp) concentration have very complicated shapes: there are several inflection points, and also the maxim ... | 1975 | 1111 |
| dihydrofolate reductase from a methotrexate-resistant escherichia coli: proton magnetic resonance studies of complexes with folate and methotrexate. | | 1975 | 1012 |
| microbiol growth in lipid emulsions used in parenteral nutrition. | parenteral nutrition via central venous catheterization is associated with serious risks, especially that of sepsis. lipid emulsion (intralipidsweden), which may be administered peripherally, was evaluated for its potential to support microbial growth. washed cultures of staphylococcus aureus, candida albicans, and three species of gram-negative rods were all capable of multiplying in the emulsion at room temperature. variations in inoculum size did not affect the growth rate. studies comparing ... | 1975 | 982 |
| aminoacylation of escherichia coli cysteine trna by selenocysteine. | | 1975 | 963 |
| derepression of certain aromatic amino acid biosynthetic enzymes of escherichia coli k-12 by growth in fe3+-deficient medium. | 3-deoxy-arabino-heptulosonic acid 7-phosphate synthase, prephenate dehydratase, tryptophan synthase, and 2,3-dihydroxybenzoylserine synthase enzyme activities are derepressed in wild-type escherichia coli k-12 cells grown on fe3+-deficient medium. this derepression is reversed when feso4 is added to the growth medium. addition of shikimic acid to the fe3+-deficient growth medium caused repression of the first three enzyme activities but not of 2,3-dihydroxybenzoylserine synthase activity. additi ... | 1976 | 1383 |
| purification to homogeneity and properties of two d-alanine carboxypeptidases i from escherichia coli. | three homogeneous preparations of d-alanine carboxypeptidases i have been obtained from escherichia coli strain h2143, termed enzymes ia, ib, and ic. enzyme ia purified from the membrane after extraction with triton x-100 appeared on sodium dodecyl sulfate gel electrophoresis to be a polypeptide doublet whose monomer molecular weights were about 32,000 and 34,000. in addition to d-alanine carboxypeptidase activity, it catalyzed a transpeptidase reaction with several substrates, bound 14cpenicill ... | 1976 | 1391 |
| inhibition of the antibacterial activity of gentamicin by urine. | urinary levels of antibiotics determine the outcome of treatment of most urinary tract infections. the antibacterial effect of gentamicin against escherichia coli and pseudomonas aeruginosa in urine was studied. with use of urinary constituents in concentrations normally found in human urine, it was shown that urine has an inhibitory effect that is dependent upon the acidity and total osmolality of the urine, as well as upon the presence of individual solutes. up to 40 times as much gentamicin m ... | 1976 | 1450 |
| proceedings: r-factor replication in an e. coli host with defective polymerase i. | | 1975 | 2720 |
| proceedings: optimal labelling of dna in thymineless escherichia coli. | | 1975 | 2721 |
| proceedings: preliminary investigations on the mode of action of the cocarcinogen a1 using bacteria. | | 1975 | 2726 |
| kinetics and mechanisms of drug action on microorganisms xxii: effects of aminosidine with and without organism pretreatment with bacteriostatic agents. | escherichia coli generation in the logarithmic growth phase was inhibited in peptone broth usp at ph 7.0 without kill below 3.0 mug/ml of aminosidine. above this value, the logarithms of the number of viables of the drug-treated culture ultimately decreased linearly with time and the slopes of these plots were independent of concentration. a concentration-dependent lag in the time of attainment of the cidal action was observed, and the extent of this lag was related to the ease of emergence of r ... | 1975 | 1509 |
| insensitivity of bacterial nucleic acid biosyntheses to a morphine-like narcotic. | | 1975 | 1683 |
| high ph ammonia toxicity, and the search for life on the jovian planets. | jovian plants have enviroments apparently suitable for the evolution of life, but nevertheless, present severe challenges to organisms. one such challenge arises from the presence of ammonia. ammonia is an efficient biocide, its effect being dependent on ph as well as on concentration. the effects of ph and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural enviornments of high ph and/or ammonia concentration. escherichi ... | 1975 | 1698 |
| effect of different ph values on the activity and quaternary structure of asparaginase in escherichia coli extracts. | the effect of low ph values on the activity and stability of the quaternary structure of asparaginase from escherichia coli was investigated at early stages of purification of the enzyme. acidification of the e. coli extract was most effective before the biomass separation. this procedure helped to separate biomass together with coagulated ballast proteins and not to reduce the activity. upon storage of the acidified solution at 5 degrees c reversible dissociation of the tetrametric structure in ... | 1975 | 1737 |
| mechanistic studies of glutamine synthetase from escherichia coli: kinetic evidence for two reaction intermediates in biosynthetic reaction. | fast reaction techniques were used to study the kinetics of protein fluorescence intensity changes that are associated with the reactions of unadenylylated escherichia coli glutamine synthetase l-glutamate: ammonia ligase (adp-forming), ec 6.3.1.2 with its substrates. it was established that the synthesis of glutamine occurs by a stepwise mechanism. during the catalytic process two fluorometrically distinct intermediates were observed. both forward and reverse rate constants which lead to the fo ... | 1976 | 1758 |
| a method for the regulation of microbial population density during continuous culture at high growth rates. | a method for the continuous culture of microorganisms is described which employs growth-dependent ph changes to control the rate of addition of fresh medium to a culture vessel. the apparatus (the "phauxostat") supports, at constant ph, long-term continuous culture at rates near or at the maximum of which the organisms are capable. the buffering capacity of the inflowing medium determines the steady-state population density of the culture, but the rate of growth is independent of the buffering c ... | 1976 | 3144 |
| the dynamic properties of biological membranes. | biological membranes must be viewed as highly dynamic, undergoing continuous structural fluctuations and changes in response to external perturbations. the study of liposomes by 31 p n.m.r. and fluorescence can reveal some of the motional characteristics of the different regions in a bilayer. asymmetric lipid distribution and how this depends on the environment is also observed by n.m.r. the nature of the interaction of amine anaesthetics and of polypeptide antibodies with membranes is discussed ... | 1975 | 1812 |
| clinical characteristics of intestinal coli infection in the city of frunze. | | 1975 | 1936 |
| immunological polyfunctionality of proteins and its meaning for the analysis of an allergen-active bacterial substrate. | it was shown with the aid of immunosorption of an allergen-active substrate of e. coli 020: k84 (no. 2-rii) that protein substances taking part in the phenomenon of cell hypersensitivity were active in the humoral immunity reactions. the allergenic and immunochemical activity served as functions of the same molecules of bacterial proteins, this substantiating the use of immunochemical analysis for the study of an allergen-active bacterial substrate. by protein denaturing it is possible to obtain ... | 1975 | 1948 |
| some properties of the alpha-hemolysin produced by a hemolytic strain of e. coli. | it was found that alpha-hemolysin of e. coli p 678 hiy+ was maximally active against human erythrocytes at ph 6.5. the hemolytic activity is characterized in time by a distinct lag-phase and a phase of the greatest velocity of the reaction immediately following it. the duration of the lag-phase and also the rate of hemolysis depends on alpha-hemolysin concentration, whose increase is accompanied by a decrease of the lag-phase and acceleration of hemolysis. there is a definite limit below which t ... | 1975 | 1949 |
| in vitro release of thymine from dna by neocarzinostatin. | | 1976 | 2169 |
| the binding of reduced nicotinamide adenine dinucleotide to citrate synthase of escherichia coli k12. | citrate synthase from escherichia coli enhances the fluorescence of its allosteric inhibitor, nadh, and shifts the peak of emission of the coenzyme from 457 to 428 nm. these effects have been used to measure the binding of nadh to this enzyme under various conditions. the dissociation constant for the nadh-citrate synthase complex is about 0.28 mum at ph 6.2, but increases toward alkaline ph as if binding depends on protonation of a group with a pka of about 7.05. over the ph range 6.2-8.7, the ... | 1976 | 2277 |
| an endonuclease from escherichia coli that introduces single polynucleotide chain scissions in ultraviolet-irradiated dna. | an endonuclease that makes single polynucleotide chain scissions in ultraviolet-irradiated dna has been purified from escherichia coli. the activity has the following properties: (a) unirradiated dna is attacked very little if at all; (b) single strand dna is not attacked, whether irradiated or not; (c) there is no requirement for divalent cations and the activity is not affected by the addition of edta; (d) the ph optimum is approximately 7; (e) the activity is inhibited by 1 m nacl, single str ... | 1976 | 3498 |
| atpase of escherichia coli: purification, dissociation, and reconstitution of the active complex from the isolated subunits. | a simple procedure for the purification of mg2+-stimulated atpase of escherichia coli by fractionation with poly(ethylene glycols) and gel filtration is described. the enzyme restores atpase-linked reactions to membrane preparations lacking these activities. five different polypeptides (alpha, beta, gamma, delta, epsilon) are observed in sodium dodecyl sulfate electrophoresis. freezing in salt solutions splits the enzyme complex into subunits which do not possess any catalytic activity. the pres ... | 1976 | 2281 |
| biosynthesis of bacterial glycogen. purification and properties of the escherichia coli b adpglucose:1,4-alpha-d-glucan 4-alpha-glucosyltransferase. | the escherichia coli b glycogen synthase has been purified to apparent homogeneity with the use of a 4-aminobutyl-sepharose column. two fractions of the enzyme were obtained: glycogen synthase i with a specific activity of 380 mumol mg-1 and devoid of branching enzyme activity and glycogen synthase ii having a specific activity of 505 mumol mg-1 and containing branching enzyme activity which was 0.1% of the activity observed for the glycogen synthase. only one protein band was found in disc gel ... | 1976 | 2288 |
| conformations of lysine-sensitive aspartokinase. | 1. the technique of differential thermal and proteolytic inactivation has been employed as a conformational probe for the lysine-sensitive aspartokinase (ec 2.7.2.4) of escherichia coli b. 2. l-amino acid inhibitors of this enzyme each induce a characteristic enzyme conformation. this is evidenced by rates of thermal and proteolytic inactivation and arrhenius activation energies for thermal inactivation which are characteristic of the amino acid present. 3. phenylalanine and leucine binding are ... | 1976 | 2308 |
| purification, molecular multiplicity and kinetic properties of "biosynthetic" l-threonine dehydratase from e. coli k-12. | "biosynthetic" l-threonine dehydratase was purified to homogeneous state with yield 29% of total activity from e. coli k-12. the cells were disrupted by means of ultra sound. nucleic acids and nucleoproteins were precipitated with protamine sulphate, the proteins were fractioned with (nh4)2so4, by gel filtration through sephadex g-25 followed by chromatography on deae-cellulose using stepways elution by changing the ph-values. the homogenity of the enzyme was shown by polyacrylamide gel disc ele ... | 1975 | 2333 |
| the purification and properties of the trimethoprim-resistant dihydrofolate reductase mediated by the r-factor, r388. | the r-factor r388 mediates the production of a trimethoprim-resistant dihydrofolate reductase. this enzyme has a different molecular weight and ph profile to the trimethoprim-sensitive enzyme of the escherichia coli host. the r-factor mediated enzyme was separated completely from the host e. coli enzyme by deae-cellulose ion-exchange chromatography. the purified r-factor enzyme was about 20 000 times less susceptible to trimethoprim than the e. coli enzyme and although it was inhibited competiti ... | 1976 | 2472 |
| 4 m guanidine hydrochloride applied to the isolation of dna from different sources. | | 1976 | 2505 |
| metallophosphoryl and apophosphoryl alkaline phosphatases. | the noncovalent phosphate (e-p) and covalent phosphory (e-p) complexes of zn(ii), cd(ii), and apoalkaline phosphatases of escherichia coli have been studied by stopped flow kinetic methods and 32p-labeling techniques. with 2,4-dinitrophenylphosphate as substrate, preincubation of the zn(ii) enzyme with pi at ph 8 slows the pre-steady state burst rate, but does not affect the burst magnitude of 1 mol of roh per enzyme dimer. preincubation of the enzyme with pi at ph 5.5 reduces the burst magnitud ... | 1976 | 2605 |
| 31p nmr of phosphate and phosphonate complexes of metalloalkaline phosphatases. | 31p nmr spectra of phosphate and phosphonate complexes of escherichia coli alkaline phosphatase have been obtained by fourier transform nmr methods. one equivalent of p1i, bound to zn(ii) alkaline phosphatase, ph 8, gives rise to a single 31p resonance 2 ppm downfield from that for pi, and assignable to the noncovalent complex, e-p. inorganic phosphate in excess of 1 eq per enzyme dimer gives rise to a resonance at the position expected for free pi. at ph 5.1, a second resonance appears 8.5 ppm ... | 1976 | 2606 |
| calcium transport driven by a proton gradient and inverted membrane vesicles of escherichia coli. | calcium transport into inverted vesicles of escherichia coli was observed to occur without an exogenous energy source when an artificial proton gradient was used. the orientation of the proton gradient was acid inside and alkaline outside. either phosphate or oxalate was necessary for transport, as was found for respiratory-driven or atp-driven uptake (tsuchiya, t., and rosen, b.p. (1975) j. biol. chem. 250, 7687-7692). phosphate accumulation was found to occur in conjunction with calcium accumu ... | 1976 | 2608 |
| the effects of age on the immune response to type iii pneumococcal polysaccharide (siii) and bacterial lipopolysaccharide (lps) in balb/c, sjl/j, and c3h mice. | type iii pneumococcal polysaccharide (siii) and bacterial lipopolysaccharide (lps) were used to evaluate b cell and t cell regulatory functions in balb/c, sjl/j, and c3h mice of various ages. it was found that the balb/c and c3h mice could mount high level plaque-forming cell (pfc) responses to siii at various ages through 110 weeks whereas the levels of the sjl/j pfc responses had begun to decline by the age of 42 weeks through the age of 80 weeks. balb/c mice were also capable of producing str ... | 1976 | 2635 |
| proceedings: interactions of chlorinated phenols with bacterial phosphatidylethonalamine monolayers in relation to antibacterial action. | | 1975 | 2696 |
| proceedings: r-factor conferred ability to mutate to trimethoprim resistance. | | 1975 | 2718 |
| sorption method of water regeneration for cosmonaut personal hygiene. | the paper describes sanitary-hygienic and technological investigations aimed at development of the sorption method of water reclamation for personal hygiene needs of cosmonauts from wash water. catamine-ab was used as a detergent with bactericidal properties. manned experiments helped to identify the conditions that provided an adequate cleaning of skin and simultaneous sterilization of wash water. the technology of wash water purification was developed, proper sorbents were selected and recomme ... | 1976 | 2804 |
| effect of a magnetic field on escherichia coli. | the decontaminating effect of the pulsing magnetic field on the e. coli infected reclaimed water was studied on two installations. the magnetic field intensity was 500 and 1000-1500 ersted and the microbial load was 1, 10 and 100 thous. microbial units per 1 ml. it was found that the magnetic treatment of water had a noticeable bactericidal effect. this indicated that the method can be used for decontamination of reclaimed water. | 1975 | 2806 |
| urine conservation by surface-active agents. | the antibacterial activity of surface-active substances -- catamine-ab, catapine b-300, giph-200 and tego-51 was measured on the e. coli and staphylococcus aureus cultures and anthracoid spores. the purpose of the measurements was to explore the use of the substances as urine conserving agents. catamine-ab showed the highest antibacterial activity. anthracoid spores exhibited the highest resistance to the substances; staphylococci were less resistant than e. coli. investigations of the effective ... | 1975 | 2807 |
| the effect of silver ion binding and ph on the buoyant density of dna and its use in fractionating heterogeneous dna. | 1. the effect of ph on the buoyant density of the complexes of ag+ with dna has been studied using 3h-labeled human dna and several bacterial dnas to determine the conditions necessary for the maximum resolution of compositional heterogeneity. in neutral cs2so4 density gradients, ag+ complexes with (g - c)-rich components are always denser than those with (a - t)-rich components, since (g - c)rich dnas have a larger affinity for ag+ than (a - t)-rich dnas and their complexes are denser than (a - ... | 1976 | 4104 |
| enzyme induction (first of three parts). | | 1976 | 2868 |
| determination of the transferase activity of l-asparaginase. | a method for determination of the transferase activity of 1-asparaginase in presence of hydroxylamine is developed. the optimally determined quantity of the enzyme was from 0.7 to 20 i. u. the conditions optimal for the enzymatic reaction and for quantitative estimation of 1-aspartyl-beta-hydroxamic acid were studied. the transferase and hydrolase activities of 1-asparaginase from e. coli were compared. the enzyme catalyzed at equal rates hydrolysis and hydroxylaminolysis of 1-asparagine. | 1975 | 3024 |
| atp synthesis by an artificial proton gradient in right-side-out membrane vesicles of escherichia coli. | | 1976 | 3178 |
| kinetics of a bacterial culture growth: validity of the affinity rule in biological systems. | the kinetic study of a process is usually performed by measuring a convenient intensive property, p, as a function of time. the "affinity rule" states that, when a given process takes place under different external constraints (e.g., different temperatures, pressures, ph values, etc.), the various p versus time curves are related by an affinity transformation parallel to the time axis: in other words the p versus log time curves are parallel and can be superimposed by translation. the validity o ... | 1975 | 2109 |
| ornithine carbamoyltransferase from escherichia coli w. purification, structure and steady-state kinetic analysis. | ornithine carbamoyltransferase from escherichia coli w was purified to homogeneity. the enzyme has a molecular weight of 105000. it is composed of three apparently identical subunits with molecular weights of 35000. the mechanism of the ornithine carbamoyltransferase enzyme system from e. coli w was investigated kinetically by using the approach of product inhibition and dead-end inhibition of both forward and reverse reactions. on the basis of the kinetic data and binding studies it appears tha ... | 1976 | 4319 |
| sulfate-reducing pathway in escherichia coli involving bound intermediates. | although a sulfate-reducing pathway in escherichia coli involving free sulfite and sulfide has been suggested, it is shown that, as in chlorella, a pathway involving bound intermediates is also present. e. coli extracts contained a sulfotransferase that transferred the sulfonyl group from a nucleosidephosphosulfate to an acceptor to form an organic thiosulfate. this enzyme was specific for adenosine 3'-phosphate 5'-phosphosulfate, did not utilize adenine 5'-phosphosulfate, and transferred to a c ... | 1976 | 3497 |
| a dacron wool packed-bed extracorporeal reactor: a kinetic study of immobilized escherichia coli ii l-asparaginase. | an extracorporeal reactor containing a packed bed of dacron fibers has been developed. escherichia coli ii l-asparaginase was coupled to the dacron using gamma-aminopropyltriethoxysilane and glutaraldehyde. the preparation had an activity of 37 iu per gram of dacron (37 degrees c). the apparent km was studied as a function of the flow rate. the data indicated that the apparent km approached the km of the native enzyme at flow rates of about 300 mg/min. in vivo use of l-asparaginase immobilized o ... | 1976 | 3508 |
| cephacetrile, a new cephalosporin: in vitro, pharmacological and clinical evaluation. | cephacetrile, a parenteral cephalosporin, was evaluated for in vitro antibacterial activity, clinical pharmacology and effectiveness in the treatment of severe infections. the antibacterial activity against 187 isolates was determined by an agar-dilution technique. the mics were 0.06 to 0.5 mug/ml for group a streptococcus, d. pneumoniae, and staph. aureus, 4-6 mug/ml for e. coli and klebsiella-enterobacter 8-32 mug/ml for pr. mirabilis and more than 500 mug/ml for ps. aeruginosa. a few strains ... | 1975 | 4377 |
| packing in a new crystalline form of glutamine synthetase from escherichia coli. | | 1976 | 3654 |
| conformational transitions of the lac repressor from escherichia coli. | | 1976 | 3656 |
| hemodynamic and respiratory responses of conscious swine to e. coli endotoxin. | the injection of a sublethal bolus of e. coli into conscious swine produces an early increase in pap and a decrease in lap. this hemodynamic effect may be secondary to the pulmonary venous constriction seen in other species, or may relate to demonstrated multiple pulmonary microemboli. hypoxemia developed in only four of 17 animals although all endotoxin-treated swine showed interstitial edema and elevated wet/dry weight ratios with normal pulmonary surfactant. in addition, endotoxin-treated swi ... | 1976 | 3664 |
| isoaccepting species of serine trna coded by bacteriophage t5sto. | by aminoacyl-trna-dna hybridization and chromatographic analysis, evidence was provided that the bacteriophage t5sto codes for two trnaser species. trinucleotide- or polynucleotide-stimulated binding experiments assigned the codons ucc or ucu to these two trnaser species. they also suggested that the synthesis of these two trnaser species does not modify the reading capacity for codons less used in escherichia coli f and corresponds to a different situation compared with the t4-coded trna's. | 1976 | 3665 |
| escherichia coli capsule bacteriophages. viii. fragments of bacteriophage 28-1. | as described previously, a host capsule depolymerase activity is associated with the particles of escherichia coli capsule bacteriophage 28-1. this is a large virus with a long, contractile tail terminating in a base plate with spikes. in the present work, isolated virions were exposed to a variety of dissociative reagents and conditions. they were then tested for residual infectivity and depolymerase activity, as well as inspected under an electron microscope. very mild acid treatment (10 to 15 ... | 1976 | 3668 |
| studies of introital colonization in women with recurrent urinary infections. v. the inhibitory activity of normal vaginal fluid on proteus mirabilis and pseudomonas aeruginosa. | normal vaginal fluid from premenopausal volunteers was inoculated with 10 strains of proteus mirabilis and 14 strains of pseudomonas aeruginosa at ph's of 4.3, 4.6 and 4.9. all bacteria were killed at ph 4.3. nine of 10 strains of proteus mirabilis and 12 of 14 pseudomonas aeruginosa were killed at ph 4.6. only 4 of 14 strains of pseudomonas aeruginosa were killed at ph 4.9, while 8 of 10 strains of proteus mirabilis were killed at the same ph. we conclude that in comparison to the common 0 grou ... | 1976 | 4631 |
| bacteriological studies on cefatrizine (s-640 p) (author's transl). | | 1976 | 4635 |
| viral pneumonias. | | 1976 | 4922 |
| biological properties of an improved transformation assay for native and denatured t4 dna. | | 1976 | 3880 |
| rapid determination of an amino acid: trna ligase.aminoacyl adenylate complex on deae-cellulose filter disks. | | 1976 | 3988 |
| a new family of low molecular weight antibiotics from enterobacteria. | | 1976 | 4071 |
| adherence of bacterial to vaginal epithelial cells. | vaginal epithelial cells from healthy women were washed and incubated in tissue culture medium with freshly isolated bacteria of the indigenous vaginal flora and with bacteria of species that have been discussed in conjunction with genital infections. after incubation and washing, the number of bacteria that adhered per cell was determined. the influence on the attachment rate of such factors as variations in the washing procedure, bacterial density, and incubation time was assessed. lactobacill ... | 1976 | 5372 |
| the state of energization of the membrane of escherichia coli as affected by physiological conditions and colicin k. | the bacterial protein colicin k, when added to sensitive escherichia coli in the presence of 3,3'-dihexyloxacarbocyanine, cuases a doubling in fluorescence of the probe. glucose and oxygen cause a decreased fluorescence while anoxia and cyanide cause a rise in fluorescence. these results in conjunction with the work of other laboratories suggest that colicin k causes a depolarization of the transmembrane electrical potential. fluorescence in the absence of colicin k was relatively independent of ... | 1976 | 4085 |
| partial purification and properties of enterobacter cloacae heat-stable enterotoxin. | cell free preparations of the whole-cell lysate and ultrafiltration (uf) fractions of broth cultures of a strain of enterobacter cloacae, isolated from a puerto rican with tropical sprue, were assayed for their ability to induce in vivo net water secretion in the rat jejunum. the whole-cell lysate and um-10 retentate of broth cultures were inactive. the um-2 retentate and filtrate were active at a concentration of 100 mug/ml or more; the toxigenic activity was entirely retained, and increased to ... | 1976 | 5376 |
| fluorine-19 nuclear magnetic resonance study of fluorotyrosine alkaline phosphatase: the influence of zinc on protein structure and a conformational change induced by phosphate binding. | 19f nuclear magnetic resonance (nmr) spectroscopy has been used to study a fully active e. coli fluorotyrosine alkaline phosphatase. the fluorotyrosine resonances provide sensitive probes of the conformational states of the protein. they were used to follow the addition of zinc or cobalt to the apoprotein, and the titration of the protein with inorganic phosphate or the inhibitor 2-hydroxy-5-nitrobenzylphosphonate. the results indicate that 2 molecules of inorganic phosphate per dimer of alkalin ... | 1976 | 4091 |
| 31p nuclear magnetic resonance study of alkaline phosphatase: the role of inorganic phosphate in limiting the enzyme turnover rate at alkaline ph. | 31p nuclear magnetic resonance (nmr) was used to directly observe the binding of inorganic phosphate to alkaline phosphatase. evidencq for the tight binding of 1.5-2.0 mol of inorganic phosphate per dimer of alkaline phosphatase is presented. two distinct forms of bound phosphate are observed, one predominating above ph 7 and representing the non-covalent e-p1 complex and the other predominating below ph 5 and representing the covalent e-p1 complex. the 31p nmr line width of the e-p1 complex ind ... | 1976 | 4092 |
| glutamine synthetase adenylyltransferase from escherichia coli: purification and physical and chemical properties. | the glutamine synthetase adenylyltransferase (ec 2.7.7.42), which catalyzes the adenylylation and deadenylylation of glutamine synthetase in e. coli, has been stabilized and purified 2200-fold to apparent homogeneity. sedimentation and electrophoresis studies show that the native enzyme is a single polypeptide chain of 115,000 +/- 5000 molecular weight with an isoelectric ph (pl) of 4.98, a sedimentation coefficient (s20.w0) of 5.6s, and a molar frictional coefficient (f/f0) of 1.52. an alpha-he ... | 1976 | 4094 |
| enzymatic properties of cloacin df13 and kinetics of ribosome inactivation. | 1. the cloacin df13-induced inactivation of ribosomes in vitro can be described as an enzyme-catalyzed reaction according to the michaelis-menten equation. most probably the cloacin acts as a unique endoribonuclease. 2. at ph 7.8 and 37 degrees c the km value for the reaction of cloacin df13 with ribosomes is 13.2 - 10(-6) m. if under these conditions the reaction mixture is supplemented with all components necessary for protein synthesis, the km changes to 17.7 - 10(-6) m. 3. the in vitro activ ... | 1976 | 4102 |
| gentamicin-susceptibility of various pathogens isolated from clinical materials. | we studied on the antibacterial activity of gentamicin against various pathogens isolated from clinical materials mainly isolated during 1974 and 1975, comparing with other antibiotics. beta hemolytic streptococci, pneumococci and enterococci are less susceptible to gentamicin than staphylococci. staph, aureus and staph. epidermidis resistant to various antibiotics are very susceptible to gentamicin, and no resistant strain to this drug was found. haemophilus influenzae, h. parainfluenzae and h. ... | 1976 | 5619 |