| interferon-producing capacity of germfree mice. | the general capacity of germfree mouse spleen cells to produce interferon in vitro in response to various stimuli was investigated. the interferon response of germfree mouse spleen cells in vitro, when compared with that of the conventionals, appears to be lower to some inducers. interferon production in vitro stimulated by hemagglutinating virus of japan (hvj) or bhk-hvj cells (bhk cells persistently infected with hvj) was apparently suppressed in germfree mouse spleen cells as compared with th ... | 1976 | 177363 |
| clinical evaluation of a novel beta-lactam antibiotic: pivmecillinam (fl 1039). | pivmecillinam, a new penicillin-like antibiotic, is a member of the amidinopenicillanic acid group. its mode of action differs from that of the classical penicillins and it exhibits no cross-resistance with them. fifty-two gerontopsychiatric patients, median age 81 years, with e. coli, klebsiella, and proteus bacteriurias were divided into three comparable groups. in a ten week open clinical trial the patients were treated with pivmecillinam, pivampicillin or the two drugs given alternately in d ... | 1975 | 177372 |
| hypersensitivity to catabolite repression in the l-arabinose operon of escherichia coli b/r is trans acting. | mutations causing hypersensitivity to catabolite repression have been assigned to gene arac (activator protein) by complementation analysis. the arao (operator region) is non-essential for catabolite repression. | 1976 | 177399 |
| growth rate modulation of four aminoacyl-transfer ribonucleic acid synthetases in enteric bacteria. | the specific activities of arginyl- glutamyl- seryl-, and valyl-transfer ribonucleic acid (trna) synthetases were measured in the wild-type and mutant strains of salmonella typhimurium lt2 and escherichia coli b/r. in media restricted only by carbon and energy source availability, the specific activities of all four enzymes were proportional to the growth rate, with the exception of seryl-trna synthetase in s. typhimurium, which remained essentially constant. structural gene densities were calcu ... | 1976 | 177401 |
| methyl methane sulfonate-sensitive mutant of escherichia coli deficient in an endonuclease specific for apurinic sites in deoxyribonucleic acid. | a methyl methane sulfonate (mms)-sensitive mutant of escherichia coli ab 1157 was obtained by n-methyl-n'-nitro-n-nitrosoguanidine treatment. the mutant strain, ab 3027, is defective both in endonuclease activity for apurinic sites in deoxyribonucleic acid (dna) and in dna polymerase i, as shown by direct enzyme assays. derivative strains, which retained the deficiency in endonuclease activity for apurinic sties (approximately 10% of the wild-type enzyme level) but had normal dna polymerase i ac ... | 1976 | 177402 |
| role of deoxyribonucleic acid polymerases and deoxyribonucleic acid ligase in x-ray-induced repair synthesis in toluene-treated escherichia coli k-12. | toluene-treated escherichia coli mutants have been used to study the roles of deoxyribonucleic acid (dna) polymerases i, ii, and iii, and of dna ligase in repair synthesis and strand rejoining following x-irradiation. in cells possessing all three dna polymerases, both a greater amount of repair synthesis ("exaggerated" repair synthesis) and failure of ligation are observed when dna ligase activity is inhibited. in a mutant lacking the polymerizing activity of dna polymerase i, exaggerated repai ... | 1976 | 177404 |
| lack of glucose phosphotransferase function in phosphofructokinase mutants of escherichia coli. | phosphofructokinase (pfka) mutants of escherichia coli are impaired in growth on all carbon sources entering glycolysis at or above the level of fructose 6-phosphate (nonpermissive carbon sources), but growth is particularly slow on sugars, such as glucose, which are normally transported and phosphorylated by the phosphoenolpyruvate, (pep)-dependent phosphotransferase system (pts). | 1976 | 177406 |
| altered deoxyribonucleotide pools in p2 eductants of escherichia coli k-12 due to deletion of the dcd gene. | deletion of the escherichia coli k-12 chromosome associated with p2 mediated education extend through the structural gene for uridine kinase, udk, and the dcd gene encoding 2'-deoxycytidine 5'-triphosphate deaminase. the lack of uridine kinase makes a positive selection possible for these strains. due to the dcd mutation, p2 eductants show large alterations in their deoxyribonucleoside triphosphate pools. | 1976 | 177407 |
| increased intestinal chromatin template activity. influence of 1alpha,25-dihydroxyvitamin d3 and hormone-receptor complexes. | 1alpha,25-dihydroxyvitamin d3 administration to rachitic chicks results in an increase in the chromatin template activity of intestinal target tissue assayed in vitro using escherichia coli rna polymerase. the maximum stimulation of template capacity was 12 to 20% over control values and occurred 2 hours after administration of the sterol. this rapid effect preceded the biologic response to 1alpha,25-dihydroxyvitamin d3 in the intestine and was not observed in other tissues such as liver or kidn ... | 1976 | 177412 |
| involvement of the glucose enzymes ii of the sugar phosphotransferase system in the regulation of adenylate cyclase by glucose in escherichia coli. | the nature of the interaction of glucose with toluene-treated cells of escherichia coli leading to inhibition of adenylate cyclase was examined by the use of analogues. those analogues with variations of the substituents about carbon atoms 1 or 2 (e.g. alpha-methylglucoside or 2-deoxyglucose) are inhibitory, and they are also substrates of the phosphoenolpyruvate-dependent sugar phosphotransferase system. analogues with changes in other parts of the molecule (e.g. 3-o-methylglucose or galactose) ... | 1976 | 177417 |
| transcription-translation and translation-messenger rna decay coupling: separate mechanisms for different messengers. | antibiotics were used to inhibit protein synthesis at specific steps in the biosynthetic pathway. in this way, it was possible to study the coupling of protein synthesis to the accumulation of biologically active mrna in t4-infected escherichia coli. functional mrna for the phage enzymes deoxynucleotide kinase (ec 2.7.4.4; atp: nucleoside monophosphate phosphotransferase or nucleosidemonophosphate kinase) and alpha-glucosyltransferase (ec 2.4.1.5; 1, 4-alpha-d-glucan: 1, 6-alpha-d-glucan 6-alpha ... | 1976 | 177977 |
| pregnancy interrupting effects of some bacterial toxins. | embryotoxic properties of shigella dysenteriae and clostridium perfringens toxins, of e. coli endotoxin, v. cholerase and e. coli enterotoxins were compared in mice. e. coli endotoxin has embryotoxic effects at all stages of pregnancy. e. coli enterotoxin v. cholerae enterotoxin and shigella dysenteriae toxin are most effective mainly at earlier stages of pregnancy. clostridium perfringens toxin has no embryotoxic effect. | 1976 | 178014 |
| fatal case of influenza pneumonia with suprainfection by multiple bacteria and herpes simplex virus. | a case of influenza pneumonia is described in which death occurred from persistence of the influenza infection and suprainfection with two bacteria, staphylococcus aureus and escherichia coli, and another virus, herpes simplex. of additional interest were the observations that this overwhelming illness developed in a previously healthy person, that typical influenza virus particles were present in antemortem lung tissue, and that the patient died despite 6 days of extracorporeal membrane oxygena ... | 1976 | 178258 |
| in vivo synergy between 6 beta-amidinopenicillanic acid derivatives and other antibiotics. | both an oral and a parenteral form of a 6beta-amidinopenicillanic acid derivative were found to have appreciable activity against gram-negative bacteria and poor activity against gram-positive bacteria in vivo. when administered orally or parenterally, definite synergy was demonstrated between the amidinopenicillins and ampicillin, amoxicillin, benzylpenicillin, cefazolin, or carbenicillin in infections with a number of gram-negative bacteria, including klebsiella, enterobacter, escherichia, pro ... | 1976 | 178275 |
| phosphorylation of double-stranded dnas by t4 polynucleotide kinase. | the phosphorylation by t4 polynucleotide kinase of various double-stranded dnas containing defined 5'-hydroxyl end group structures has been studied. particular emphasis was placed on finding conditions that allow complete phosphorylation. the dnas employed were homodeoxyoligonucleotides annealed on the corresponding homopolymers, dna duplexes corresponding to parts of the genes for alanine yeast trna, and a suppressor tyrosine trna from escherichia coli. the rate of phosphoylation of dnas with ... | 1976 | 178357 |
| regulation of uracil uptake in escherichia coli by adenosine 3',5'-monophosphate. | culture of a wild-type strain of escherichia coli in the presence of cyclic amp leads to an impairment of uracil uptake. half maximum inhibition of uracil uptake was observed at 1.5 mm cyclic amp. the effect seems to be specific since no inhibition was found in cultures supplemented with atp, adp or 5'-amp. similarly the inhibition was not observed in cultures of a mutant deficient in the cyclic amp receptor protein. the inhibition in uracil uptake, found in bacteria cultured in the presence of ... | 1976 | 178363 |
| inhibition of rat liver rna polymerases by action of the methylating agents dimethylnitrosamine in vivo and methyl methanesulfonate in vitro. | dimethylnitrosamine maximally inhibits rat liver nuclear rna synthesis by 50% at a dose of 40 mg/kg of body weight. the inhibition develops during the first 4 hr and persists through the 12th hr. all parenchymal cells of the lever lobule seem to be affected. the decreased rna synthesis can be accounted for entirely by an inhibition of the rna polymerase activities quantitatively solubilized and partially purified. a similar inhibition of the polymerase activities was demonstrated in the intact n ... | 1976 | 178432 |
| turnover at nicotinamide adenine dinucleotide in cultures of human cells. | the rate of turnover of nicotinamide adenine dinucleotide (nad) in the human cell line, d98/ah2, has been estimated by measuring the rates of entry into and exit from nad molecules of 14c-adenine. in one set of experiments, cells were labeled by growth in medium containing 14c-adenine for six hours and then shifted to medium without labeled adenine. the loss of 14c-adenine from the adenine nucleotide and pyridine nucleotide pools was measured, and the data were analyzed using an analytical treat ... | 1976 | 178671 |
| spin labeled nucleic acids. | homopolyribonucleotides and e. coli dna wer spin labeled with an iodoacetamide-nitroxide compound. the extent of labeling is highly dependent upon the nature of the base and the secondary structure of the nucleic acid. this spin label-polymer linkage is unstable at high temperatures and in phosphate buffers. in order to determine the effect of changes in the environment of nucleic acids on the esr signals of their attached spin labels, the polynucleotides were subjected to temperature and viscos ... | 1976 | 179060 |
| [the "vaccination reaction" syndrome of broilers after vaccination against newcastle disease and infectious bronchitis (author's transl)]. | in a part of the broiler flocks vaccinated against newcastle disease (n.c.d) and infectious bronchitis (i.b.), disease symptoms of lingering nature have been observed, generally in the second half of the rearing period. in a practical investigation with weekly examinations of chickens, supplemented by a serological examination of twenty-four animals per flock at the age of six weeks, it was hoped to establish the factors responsible for this "vaccination reaction". in the district under notice t ... | 1976 | 179162 |
| antibacterial activity of 15-azasteroids alone and in combination with antibiotics. | a new class of 15-azasteroid analogues has been synthesized and tested for antimicrobial activity. the compounds 1, 10, 11, 11a-tetrahydro-7-methoxy-11a-methyl-2h-naphth (1,2-g) indol (methoxyimine) and 1,10,11,11a-tetrahydro-11a-methyl-2h-naphth (1,2-g) indol-7-ol (hydroxyimine) inhibit the growth of bacillus subtillis and escherichia coli at concentrations as low as 10-5 m. addition of either compound to the growth medium casued a rapid inhibition in the transport of radioactive glucose, uraci ... | 1976 | 179169 |
| interactions of plant viral rnas and trna nucleotidyl transferase. | ribonucleic acid from tmv and bmv can accept amp and cmp when digested with vpd. this incorporation is catalyzed by e. coli and yeast trna nucleotidyl transferases. complex formation is obtained between tymv rna and trna nucleotidyl transferase in sucrose gradients while tmv and bmv rnas failed to form a complex in the same conditions. the affinity of the enzyme for viral rnas is lower than the affinity for trna as shown by complex formation on nitrocellulose filters and competition with trna. c ... | 1976 | 179457 |
| energy metabolism of bdellovibrio bacteriovorus. ii. p/o ratio and atp pool turnover rate. | the p/o ratio of bdellovibrio bacteriovorus, strain bd 109 sa, was evaluated by two different methods based on the determination of energy-rich phosphate bonds and either nadh oxidation or oxygen-uptake. p/o values calculated on the basis of nadh oxidation were up to 6, which has to be regarded as being overestimated. p/o values calculated from energy-rich phosphate bonds and oxygen uptake were around 2. the p/o values determined for escherichia coli b were similar. the loss of phosphorylation e ... | 1976 | 179488 |
| effects of sulphate-limited growth in continuous culture on the electron-transport chain and energy conservation in escherichia coli k12. | growth of escherichia coli k12 in a chemostat was limited by sulphate concentrations lower than 300 mum. the synthesis of extracellular polysaccharide and a change in morphology accompanied sulphate-limited growth. growth yields with respect to the amount of glycerol or oxygen consumed were sixfold and twofold lower respectively under these conditions than when growth was limited by glycerol. sulphate-limited cells lacked the proton-translocating oxidoreduction segment of the electron-transport ... | 1975 | 179525 |
| [new concepts on the etiopathogenesis of diarrhea]. | the author discusses new knowledge concerning e. coli enterotoxins and duovirus in the production of diarrheal disease. | 1976 | 179558 |
| regulation of a metabolic system in vitro: synthesis of threonine from aspartic acid. | six enzymes involved in the conversion of aspartate to threonine have been extracted from escherichia coli and separated from each other. two of these enzymes, aspartokinase and homoserine dehydrogenase, have also been partially purified from rhodopseudomonas spheroides. in an attempt to determine whether small changes in the kinetic properties of individual enzymes are important to the regulation of metabolic flux through a coupled reaction system, the partially purified enzymes were recombined ... | 1976 | 179564 |
| inhibition of growth and aspartokinase activity of salmonella typhimurium by thialysine. | thialysine (s-2-aminoethyl cysteine) is an analog of lysine and has been reported to inhibit the lysyl-trna synthetase activity of escherichia coli. this analog inhibits the growth of salmonella typhimurium when added to glucose minimal medium at concentrations of 1.25 mm or greater. the addition of lysine with thialysine restores the normal growth rate, whereas, methionine, valine, or leucine each enhances the growth inhibition casued by thialysine. enzyme assays demonstrate that thialysine inh ... | 1976 | 179582 |
| growth of a mutant of escherichia coli k-12 on xylitol by recruiting enzymes for d-xylose and l1,2-propanediol metabolism. | wild type escherichia coli k-12 cannot grow on xylitol and we have been unsuccessful in isolating a mutant directly which had acquired this new growth ability. however, a mutant had been selected previously for growth on l-1,2-propanediol as the sole source of carbon and energy. this mutant constitutively synthesized a propanediol dehydrogenase. recently, we have found that this dehydrogenase fortuitously converted xylitol to d-xylose which could normally be metabolized by e. coli k-12. in addit ... | 1976 | 179583 |
| [escherichia coli membrane-bound polyphosphatase]. | a complex of polyphosphatase with e. coli membranes has been isolated and studied. it is shown by gel-filtration through g-200 sephadex and centrifugation in sucrose concentration gradient that about 5% of polyphosphatase total content in cells is bound with the heterogenous fraction containing smooth membranes and the ribosome-membrane complex. on the basis of the data obtained it is suggested that the formation of a complex of polyphosphatase with membranes is a stage of synthesis and secretio ... | 1976 | 179613 |
| [cyclic 3',5'-adenosine monophosphate stimulation of chloramphenicol-acetyltransferase synthesis in bacterial cellular systems]. | a study was made of the effect of cyclic cyclic 3',5'-adenosinmonophosphate (c-amp) on the production of chloramphenicol-acetyltranspherase (cat) enzyme by whole bacterial cells in the strains of e. coli csh-2/r222 and wz-78/r222 (cya855). it was shown that cat synthesis in the e. coli wz-78/r222 strain was two times less in comparison with the e. coli csh-2/r222 strain. c-amp only insignificantly increased the production of cat by the e. coli csh-2/r222 strain, but considerably influenced the p ... | 1975 | 179643 |
| cytokinin ocntents and camp metabolism during growth of escherchia coli. | during escherichia coli growth, we found an inverse correlation between free cytokinin content and camp level. the rates of synthesis of adenylate-cyclase and camp-phosphodiesterase were practically constant. | 1976 | 179840 |
| trapping of an intermediate in the oxidation-reduction cycle of cytochrome d in escherichia coli. | | 1976 | 179880 |
| proceedings: stimulation of intestinal cyclic amp by a heat stable toxin of escherichia coli 0148. | | 1976 | 179916 |
| repression of escherichia coli carbamoylphosphate synthase: relationships with enzyme synthesis in the arginine and pyrimidine pathways. | cumulative repression of escherichia coli carbamoylphosphate synthase (cpsase; ec 2.7.2.9) by arginine and pyrimidine was analyzed in relation to control enzyme synthesis in the arginine and pyrimidine pathways. the expression of cara and carb, the adjacent genes that specify the two subunits of the enzyme, was estimated by means of an in vitro complementation assay. the synthesis of each gene product was found to be under repression control. coordinate expression of the two genes was observed u ... | 1976 | 179975 |
| isolation and heteroduplex mapping of a lambda transducing bacteriophage carrying the structural genes for carbamoylphosphate synthase: regulation of enzyme synthesis in escherichia coli k-12 lysogens. | a n-lambda bacteriophage transducing the structural genes for escherichia coli k-12 carbamoylphosphate synthase (glutamine) (cpsase; ec 2.7.2.9) has been isolated and analyzed both genetically and physically. the whole int-n region is substituted for a short chromosomal segment corresponding almost exactly to the car locus. the study of cpsase, ornithine carbamoyltransferase, and aspartate carbamoyltransferase regulation in carriers of lambdadcar confirms the previously reported participation of ... | 1976 | 179976 |
| control of the synthesis of alkaline phosphatase and the phosphate-binding protein in escherichia coli. | using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunological techniques, we have compared the synthesis of the phoa protein (alkaline phosphatase) and the phos protein (phosphate-binding protein) in response to the level of phosphate in the medium in different genetic backgrounds containing the known alkaline phosphatase control mutations. both proteins are produced in excess phosphate media in a phor1a- strain, whereas neither protein is produced in a phob- strain even unde ... | 1976 | 179980 |
| association of messenger ribonucleic acid with 70s monosomes from down-shifted escherichia coli. | the complexed 70s ribosomes (monosomes) that accumulate in escherichia coli after an energy source shift-down were examined in an electron microscope. in all cases, the ribosomes lie at or near one end of a ribonucleic acid (rna) strand. this messenger rna (mrna) has a mean length of 168 nm and a length-average length of 200 nm, sufficient to code for polypeptides of a weight-average molecular weight of 20,000. the length distribution indicates that these strands are a reasonable representation ... | 1976 | 179981 |
| phosphatidylserine synthetase mutants of escherichia coli. genetic mapping and membrane phospholipid composition. | mutants of escherichia coli k-12 defective in cdp-diglyceride:l-serine phosphatidyltransferase (phosphatidylserine synthetase) can be isolated by a rapid autoradiographic screening assay described previously (raetz, c. r. h. (1975) proc. natl. acad. sci. u. s. a. 72, 2274-2278). four organisms of this kind have now been characterized. the gene (designated pss) which is altered in these mutants is closely linked to the nadb locus near minute 49 on the e. coli chromosome. strains carrying the pss- ... | 1976 | 179992 |
| modification of escherichia coli dna ligase by cleavage with trypsin. | limited treatment of escherichia coli dna ligase with trypsin results in rapid loss of dna joining activity. however, the ability to react with dpn to form the covalent enzyme-amp intermediate is unaffected. the cleaved enzyme is also unable to catalyze the formation of dna-adenylate, the second covalent intermediate in the ligase-catalyzed reaction. these findings demonstrate that portions of the dna ligase molecule that are required for phosphodiester bond formation are not required for at lea ... | 1976 | 179997 |
| laboratory investigation of diarrhea in travelers to mexico: evaluation of methods for detecting enterotoxigenic echerichia coli. | a laboratory investigation was conducted on cultures collected from travelers before, during, and after a trip to mexico to characterize the etiology of traveler's diarrhea. four laboratory methods for detecting enterotoxigenicity of escherichia coli were evaluated: the infant mouse assay, the chinese hamster ovary (cho) cell assay, the y1 adrenal cell assay, and the rabbit ileal loop. although a number of common enteric pathogens were identified as a cause of traveler's diarrhea, including six ... | 1976 | 180047 |
| regulation of bacterial motility by cyclic nucleotides and effect of biogenic amines. | when assayed by a newly devised, simple and quantitative method, "motilometry", the motility of e. coli s-26 was found stimulated by cyclic adenosine 3':5'-monophosphate (cyclic amp) and 8-hydroxy cyclic amp as well as histamine, catecholamines and inhibited by cyclic guanosine 3':5'-monophosphate (cyclic gmp). the stimulation elicited by cyclic amp or other biogenic amines was reversed by cyclic gmp. the experimental significance and implicaton of these findings are discussed. | 1976 | 180064 |
| biochemical and genetic characterization of a carbamyl phosphate synthetase mutant of escherichia coli k12. | an unusual escherichia coli k12 mutant for carbamyl phosphate synthetase is described. the mutation was generated by bacteriophage mui insertion and left a 5% residual activity of the enzyme using either ammonia or glutamine as donors. the mutation is recessive to the wild-type allele and maps at or near the pyra gene, but the mutant requires only arginine and not uracil for growth. by a second block in the pyrb gene it was possible to shift the accumulated carbamyl phosphate to arginine biosynt ... | 1976 | 180236 |
| enhanced template activity in chromatin from adrenal medulla after phosphorylation of chromosomal proteins. | translocation of protein kinase to the nucleus had been implicated earlier in the transsynaptic control of gene expression mediated by cholinergic nerves in adrenal medulla. phosphorylation of chromosomal proteins by adenosine 3',5'-monophosphate-dependent protein kinase and adenosine 3',5'-monophosphate enhances the template activity of chromatin from adrenal medulla. when homologous rna polymerase ii is used the relative activation is greater than that obtained with escherichia coli rna polyme ... | 1976 | 180597 |
| bacteriological quality and shelf life of ground beef. | the bacteriological quality of unfrozen raw ground beef was evaluated after 0, 3, 6, 9, 12, 15, and 18 days of storage at 29 +/- 1 f (-1.7 +/- 0.6 c). at the time of fabrication, all of the ground beef samples contained 10(6) or fewer total aerobic and psychrotrophic bacteria/g; 81% contained 100 or fewer coliforms/g; 94% contained 100 or fewer escherichia coli/g; and all of the samples contained 100 or fewer coagulase-positive staphylococcus aureus and clostridium perfringens/g. total aerobic a ... | 1976 | 180886 |
| a kinetically important phosphoryl-enzyme intermediary in the intrinsic purine nucleoside-5'-diphosphokinase activity of escherichia coli acetate kinase. | | 1976 | 180890 |
| kinetic characterization of the membrane-bound cytochromes of escherichia coli grown under a variety of conditions by using a stopped-flow dual-wavelength spectrophotometer. | a study was made of the rapid oxidation kinetics of the cytochromes of escherichia coli. the b-type cytochromes were kinetically heterogeneous, with one species (presumably cytochrome o) oxidized so rapidly that it could fully support observed oxidation rates. cytochrome d but not cytochrome a1 was also kinetically competent to support respiration. however, in cells grown anaerobically in the presence of no3-, cytochrome d exhibited slow oxidation kinetics and a red-shift in its reduced-minus-ox ... | 1976 | 180972 |
| electron-paramagnetic-resonance studies on the molybdenum of nitrate reductase from escherichia coli k12. | studies on the respiratory nitrate reductase (ec 1.7.99.4) from escherichia coli k12 by electron-paramagnetic-resonance spectroscopy indicate that its molybdenum centre is comparable with that in other molybdenum-containing enzymes. two mo(v) signals may be observed; one shows interaction of mo(v) with a proton exchangeable with the solvent and has: a (1h) 0.9-1.2mt; g1 = 1.999; g2=1.985; g3 = 1.964; gav. = 1.983. molybdenum of both signal-giving species may be reduced with dithionite and reoxid ... | 1976 | 180982 |
| selective inactivation of the transacylase components of the 2-oxo acid dehydrogenase multienzyme complexes of escherichia coli. | 1. the reaction of the pyruvate dehydrogenase multienzyme complex of escherichia coli with maleimides was examined. in the absence of substrates, the complex showed little or no reaction with n-ethylmaleimide. however, in the presence of pyruvate and n-ethylmaleimide, inhibition of the pyruvate dehydrogenase complex was rapid. modification of the enzyme was restricted to the transacetylase component and the inactivation was proportional to the extent of modification. the lipoamide dehydrogenase ... | 1976 | 180985 |
| enzymatic binding of aminoacyl transfer ribonucleic acid to ribosomes: the study of binding sites of 2' and 3' isomers of aminoacyl transfer ribonucleic acid. | the mechanism of enzymatic binding of aatrna to the acceptor site escherichia coli ribosomes has been studied using the following aminoacyl oligonucleotides as models of the 3' terminus of aa-trna: c-a-phe, c-a-(2'-phe)h, and c-a(2'h)phe. t-psi-c-gp was used as a model of loop iv of trna. the ef-t dependent binding of phe-trna to ribosomes (in the presence of either gtp or gmppcp) and the gtpase activity associated with ef-t dependent binding of the phe-trna were inhibited by c-a-phe,c-a(2'phe)h ... | 1976 | 181048 |
| inactivation of the t7 coliphage by monofunctional alkylating agents. action of phage adsorption and injection of its dna. | alkylation by ethyl or methyl methanesulfonate to an extent that inactivates more than 99.5% of t7 coliphages has no effect on phage adsorption on escherichia coli b cells, but decreases the amount of phage dna injected into the host cells. depurination interferes with the injection of the phage dna. failure to inject the whole phage genome thus appears to be a cause of the immediate as well as of the delayed inactivation of the t7 coliphage treated by monofunctional alkylating agents; the hypot ... | 1976 | 181068 |
| joining of simian virus 40 dna molecules at endonuclease r eco ri sites by polynucleotide ligase and analysis of the products by agarose gel electrophoresis. | dna molecules cut with endonuclease r eco ri can be joined at eco ri cleavage sites by incubation with polynucleotide ligase. in order to define the optimum conditions for this reaction, linear simian virus 40 dna molecules (sv40(lri)) produced by endonuclease r eco ri cleavage of sv40 form i dna were joined using polynucleotide ligases specified by bacteriophage t4 and escherichia coli. we have determined that the concentration of the substrate dna molecules is the most important factor determi ... | 1976 | 181070 |
| in vivo activation by polymyxin b of phospholipase from pseudomonas aeruginosa and escherichia coli. | | 1976 | 181357 |
| pathway of thiamine pyrophosphate synthesis in micrococcus denitrificans. | the pathway of thiamine pyrophosphate (tpp) biosynthesis, which is formed either from exogeneously added thiamine or from the pyrimidine and thiazole moieties of thiamine, in micrococcus denitrificans was investigated. the following indirect evidence shows that thiamine pyrophosphokinase (ec 2.7.6.2) catalyzes the synthesis of tpp from thiamine: (i) [35s]thiamine incubated with cells of this microorganism was detected in the form of [35s]thiamine; (ii) thiamine gave a much faster rate of tpp syn ... | 1976 | 181359 |
| mutations affecting catabolite repression of the l-arabinose regulon in escherichia coli b/r. | expression of the l-arabinose regulon in escherichia coli b/r requires, among other things, cyclic adenosine-3', 5'-monophosphate (camp) and the camp receptor protein (crp). mutants deficient in adenyl cyclase (cya-), the enzyme which synthesizes camp, or crp (crp-) are unable to utilize a variety of carbohydrates, including l-arabinose. ara+ revertants of a cya-crp- strain were isolated on 0.2% minimal l-arabinose plates, conditions which require the entire ara regulon to be activated in the ab ... | 1976 | 181362 |
| disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in escherichia coli. | in escherichia coli, l-fucose is dissimilated via an inducible pathway mediated by l-fucose permease, l-fucose isomerase, l-fucose kinase, and l-fuculose 1-phosphate aldolase. the last enzyme cleaves the six-carbon substrate into dihydroxyacetone phosphate and l-lactaldehyde. aerobically, lactaldehyde is oxidized to l-lactate by a nicotinamide adenine dinucleotide (nad)-linked dehydrogenase. anaerobically, lactaldehyde is reduced by an nadh-coupled reductase to l-1,2-propanediol, which is lost ... | 1976 | 181364 |
| growth on d-arabitol of a mutant strain of escherichia coli k12 using a novel dehydrogenase and enzymes related to l-1,2-propanediol and d-xylose metabolism. | escherichia coli k12 cannot grow on d-arabitol, l-arabitol, ribitol or xylitol (reiner, 1975). using a mutant of e. coli k12 (strain 3; sridhara et al., 1969) that can grow on l-1,2-propanediol, a second-stage mutant was isolated which can utilize d-arabitol as sole source of carbon and energy for growth. d-arabitol is probably transported into the bacteria by the same system as that used for the transport of l-1,2-propanediol. the second-stage mutant constitutively synthesizes a new dehydrogena ... | 1976 | 181526 |
| interactions of n6-(delta2-isopentenyl)adenine with cyclic amp on the regulation of growth and beta-galactosidase synthesis in escherichia coli. | | 1976 | 181529 |
| a continuous assay for an intracellular enzyme: the analysis of acetate kinase in escherichia coli. | | 1976 | 182034 |
| regulation of membrane functions and fatty acid composition in escherichia coli by cyclic amp receptor protein. | | 1976 | 182080 |
| factors influencing the response of escherichia coli to antibiotics in conditions prevailing in the infected urinary bladder. | the response of a sensitive strain of escherichia coli to a variety of antibiotics was examined in an in vitro model which simulates the hydrokinetic features of the urinary bladder. recovery of bacterial cultures from antibiotic effects was observed following exposure to bactericidal and bacteristatic antibiotics and no substantial difference was noted between the effectiveness of bacteristatic and bactericidal agents except that bacteristatic antibiotics were more influenced by alteration of t ... | 1976 | 182196 |
| modification of membrane lipid: physical properties in relation to fatty acid structure. | differential scanning calorimetry (dsc) and electron spin resonance (esr) measurements were made to characterize how modifications in the fatty acid composition of escherichia coli affected the thermotropic phase transition(s) of the membrane lipd. when the fatty acid composition contained between 20 and 60% saturated fatty acids, the dsc curves for isolated phospholipids and cytoplasmic membranes showed a broad (15-25 degree c) gel to liquid-crystalline phase transition, the position of which d ... | 1976 | 182201 |
| methionyl-trna synthetase from escherichia coli: active stoichiometry and stopped-flow analysis of methionyl adenylate formaiton. | native dimeric methionyl-trna synthetase and its monomeric proteolytic fragment are shown to form and to bind 1 mol of methyionyl adenylate per polypeptide chain. moreover, at 25 degrees c, each monomer of the dimeric native enzyme behaves independently, exhibiting the same parameters for the methionine activation reaction as does the monomeric modified enzyme. these results were obtained using several independent methods including equilibrium and nonequilibrium dialysis, active site and tryptop ... | 1976 | 182214 |
| synthesis of inducible enzyme in escherichia coli recovering from prolonged energy starvation. | a marked breakdown of ribosomes and rrna occurs in escherichia coli cells during prolonged deprivation of a carbon source (energy starvation). in e. coli recovering from energy starvation: (a) synthesis of rna started immediately, total protein synthesis showed a delay of 5 to 10 minutes; (b) beta-galactosidase, tryptophanase and serine deaminase could not be induced in the first 50--70 min; (c) a lag of 60 min in the synthesis of beta-galactosidase was observed in a lac constitutive mutant of e ... | 1976 | 182224 |
| effects of colicins k and e1 on the glucose phosphotransferase system. | 1. glycerol-grown cells of escherichia coli and its mutant unca, treated with colicin e1 or k, exhibited a several-fold higher level of alpha-methylglucoside uptake than untreated cells. this stimulation was independent of the carbon source present during the uptake test. in a mutant strain that has elevated levels of alpha-methylglucoside accumulation the addition of colicin e1 or carbonylcyanide m-chlorophenylhydrazone (cccp) did not further enhance the uptake. 2. colicins k and e1 decreased t ... | 1976 | 182245 |
| partial purification and properties of diglyceride kinase from escherichia coli. | diglyceride kinase (diacylglycerol kinase, e.c. 2.7.1.-), an enzyme localized in the inner membrane of escherichia coli, has been purified about 600-fold. the purified enzyme exhibits an absolute requirement for magnesium ion; its activity toward both lipid and nucleotide substrates is stimulated by diphosphatidylglycerol or other phospholipids. adenine nucleotides are much better substrates for the enzyme than are other purine or pyrimidine nucleotides. the purified enzyme preparation catalyzes ... | 1976 | 182252 |
| repair of x-ray-induced single strand breaks in toluenized escherichia coli cells. | we have used sedimentation in alkali to estimate the repair of x-ray-induced single strand breaks in the dna of irradiated toluenized escherichia coli cells. extensive repair requires no exogenous cofactors except atp although other individual ntps (except u) or dntps can substitute for atp. there is no repair in pola or resa cells and since nicotinamide mononucleotide (nmn) inhibits repair in wild type cells we interpret the results as indicating that both ligase and polymerase i are needed for ... | 1976 | 182255 |
| the atp dependence of the incision and resynthesis steps of excision repair. | escherichia coli made permeable by treatment with toluene can perform a mode of dna synthesis that is stimulated by ultraviolet radiation and closely resembles the resynthesis step of excision repair. if ultraviolet-irradiated toulene-treated cells are incubated in an assay mixture with atp but without the four deoxyribonucleoside triphosphates (dntps) or nad, accumulations of single-strand breaks in the dna are detected by alkaline sucrose gradient analysis. a second incubation with the dntp's ... | 1976 | 182256 |
| the restriction endonucleases in bacillus amyloliquefaciens n strain. substrate specificities. | two species of restriction endonuclease were isolated by gel filtration and deae-cellulose chromatography from a cell-free extract of bacillus amyloliquefaciens (b. subtilits) n strain; a lower molecular weight endonuclease (endonuclease r.bamni) and a higher molecular-weight one (endonuclease r.bamnx). both of them required only mg2+ for their activities. endonuclease r.bamnx introduced a larger number of site-specific scissions in excherchia coli phage lambda dna that endonuclease r.bamni did. ... | 1976 | 182257 |
| further purification and characterization of t4 endonuclease v. | t4 endonuclease v, which is involved in repair of ultraviolet-damaged dna, has been purified 3600 fold from t4d-infected escherichia coli. the enzyme shows optimal activity at ph 7.2 and does not require added divalent ions. endonuclease v attacks both native and heat-denatured dna provided that the dna has been irradiated, and the enzyme activity is dependent on the dose of ultraviolet irradiation. the rate and the extent of the reaction are greater with irradiated native dna although the km va ... | 1976 | 182258 |
| repair of dna damaged by methyl methanesulfonate in bacteriophage t4. | a highly purified preparation of t4 endonuclease v does not degrade dna alkylated with methyl methanesulfonate, and the methyl methanesulfonate sensitivity of t4 wild type and x mutant is not affected by the v mutation. thus, t4 endonuclease v, the v gene product, does not seem to be involved in a repair or an abortive repair of methyl methanesulfonate-damaged t4 dna. the x and y genes of t4 and the pola and the uvrd genes of escherichia coli are concerned with the repair of methyl methanesulfon ... | 1976 | 182259 |
| [elaboration of chloramphenicol acetyltransferase by cells of e. coli k-12 under conditions altering the intracellular concentration of cyclic adenosine-3',5'-monophosphate]. | the influence of camp, acth and glucose on the stimulation of chloramphenicol acetyl transferase synthesis in the cells of e. coli csh-2/r222 and e. coli wz-78/r222. (cya855) was examined. glucose proved to decrease the enzyme synthesis in e. coli csh-2/r222, causing catabolite repression; 5 mm of camp and 1000 mug/ml acth overcame the latter. the enzyme synthesis in e. coli wz-78/r222 was insensitive to the catabolite repression; as to acth - it failed to cause stimulation ofchloramphenicol ace ... | 1976 | 182302 |
| mechanism of the inhibition of transcription by pr toxin, a mycotoxin from penicillium roqueforti. | pr toxin, a mycotoxin synthesized by penicillium roqueforti, impairs the transcriptional process in liver cells; the two main rna polymerase systems (enzymes a and b) are affected by pr toxin. the toxin does not require an enzymic conversion before interfering with in vitro rna synthesis. addition of ammonium sulphate completely prevents the inhibition of transcription by pr toxin. in vitro results, using rna polymerase purified from e. coli, suggest that pr toxin impairs the activity of the rna ... | 1976 | 182392 |
| copper toxicity: evidence for the conversion of cupric to cuprous copper in vivo under anaerobic conditions. | we have determined the toxicity to cells of escherichia coli b of cupric copper applied under aerobic and anaerobic conditions in two ways. the growth of cells in liquid medium incorporating cupric copper shows differential inhibition, comparing aerobic and anaerobic conditions--toxicity being greater under anoxia. the growth of colonies upon agar plates incorporating cupric copper does not show such a differential effect. we conclude that colonies on plates are largely anoxic even when incubate ... | 1976 | 182394 |
| use of polymyxin b, levallorphan, and tetracaine to isolate novel envelope mutants of escherichia coli. | mutants of escherichia coli were isolated by their resistance to the bacteriocidal effects of the membrane-active drugs polymyxin b, levallorphan, and tetracaine. the mutants were examined for additional changes in cellular physiology evoked by the lesions; many polymyxin-resistant strains had a concomitant increased sensitivity to anionic detergents, and several strains of each type had concomitant alterations in generation time and morphology. mutants of each class (polymyxin resistant, tetrac ... | 1976 | 182670 |
| progesterone-binding components of chick oviduct. in vitro effects of purified hormone-receptor complexes on the initiation of rna synthesis in chromatin. | we have investigated the manner by which progesterone receptors act to induce initiation of rna synthesis in a cell-free system derived from chick oviduct. a method utilizing rifampicin enabled us to measure the formation of binary initiation complexes between rna polymerase and chick oviduct chromatin (tsai, m.-j., schwartz, r.j., tsai s.y., and o'malley, b.w. (1975) j.biol. chem. 250, 5165-5174) and allowed for the quantitative assessment of rna chain initiation sites, rna chain propagation ra ... | 1976 | 182691 |
| letter: rheovirus and e. coli in infantile enteritis. | | 1976 | 182725 |
| control of the sequential utilization of glucose and fructose by escherichia coli. | in escherichia coli (atcci5224; ml308), glucose and fructose phosphotransferase systems (pt-systems) are constitutive but activities are increased five and 10-fold respectively by aerobic growth on their respective substrates in defined media. in mixtures, glucose is used preferentially and the fructose pt-system activity is kept at its minimum; but, on glucose exhaustion, it overshoots its steady-state level and growth continues on fructose without lag. cyclic amp prevents overshoot. continuous ... | 1976 | 182905 |
| mutagenic and inactivating effects of methyl alkylaminosulfonates on escherichia coli. | methyl alkylamino methanesulfonates are mutagenic agents as shown by treating several strains of e. coli at ph 7. methyl methylaminosulfonate (ch3-nh-so3-ch3) was more efficient than methyl ethylaminosulfonate (c2h5-nh-so3-ch3) which itself was more efficient than methyl isopropylaminosulfonate (c3h7-nh-so3-ch3). methyl methylaminosulfonate seemed to be at least as effective as methyl methanesulfonate (ch3-so3-ch3). methyl methylaminosulfonate produced a yield of up to 1% of auxotrophic mutants. ... | 1976 | 183111 |
| [the influence of infectious bronchitis virus on egg production, fertility, hatchability and mortality rate in chickens (author's transl)]. | in 35 flocks comprising almost 100,000 white plymouth rock birds producing hatching eggs, infectious bronchitis (ib) caused a decline in production which appeared to be connected with the age of the birds, when the outbreak started (table i). in outbreaks of ib in pullets 3-4 weeks before they are ready to lay there is a considerable risk of delay of production and a generally too low yield (fig 1). egg laying birds, 25-34 weeks of age, suffered a drop in production from 20-80% (on an average 40 ... | 1976 | 183182 |
| transfer of trnas to somatic cells mediated by sendai-virus-induced fusion. | trnas from yeast (trnaphe and 4s rna) and escherichia coli (suiii+ trnaityr) have been transferred to mouse cells by means of a two-step transfer procedure [loyter, zakai, and kulka (1975) j. cell biol. 66, 292-304; schlegel and rechsteiner (1975) cell 5, 371-379]. in the first stage of the transfer trnas were incorporated into rabbit red blood cells (rbcs). thereafter, the loaded erythrocytes were fused with recipient mouse cells by means of sendai virus. at least 0.3-0.4% of the total input of ... | 1976 | 183211 |
| changes in tertiary structure accompanying a single base change in transfer rna. proton magnetic resonance and aminoacylation studies of escherichia coli trnamet f1 and trnamet f3 and their spin-labeled (s4u8) derivatives. | the properties of escherichia coli trnamet f1 and trnamet f3 that differ by only one base change, m7g to a at position 47, have been compared structurally by proton magnetic resonance and functionally by the aminoacylation reaction. the nmr spectra of the two trna species in the region between 0 and 4 ppm below 4,4-dimethyl-4-silapentane-1-sulfonic acid (dss) (methyl and methylene region) were the same except for the absence of the lowest field peak at 3.8 ppm in trnamet f3, thus unequivocally i ... | 1976 | 183808 |
| lysine-sensitive aspartokinase of escherichia coli k12. synergy and autosynergy in an allosteric v system. | the interactions of the lysine-sensitive aspartokinase of e. coli k12 with lysine and leucine, as evidenced in the inhibition and binding curves, are well explained by the equations of an allosteric v model. mathematical treatments of such a model lead to new linearized plots. these representations are applied to our experimental results and allow the direct determination of some parameters of the model (equilibrium constant l' and leucine dissociation constants). the other parameters are obtain ... | 1976 | 183809 |
| the efficacy of a modified live reo-like virus vaccine and an e. coli bacterin for prevention of acute undifferentiated neonatal diarrhea of beef calves. | | 1976 | 183883 |
| ca2+-induced conformational changes of spin-labeled g2 chain bound to myosin and the effect of phosphorylation. | one of the low molecular weight components of myosin, g2, was isolated by alkali treatment of myosin and was chemically modified with a spin label reagent, 4-maleimido-2,2,6,6-tetramethylpiperidinooxyl. the label on g2 showed a rather weakly immobilized esr spectrum and it was clearly affected by ca2+; the half-maximal change was at around pca 4. the spin-labeled g2 was incorporated into myosin by exchange with the intrinsic g2 of myosin in 0.6 m kscn or 4 m lic1. the label on g2 became strongly ... | 1976 | 184078 |
| physical and chemical studies on bacterial superoxide dismutases. purification and some anion binding properties of the iron-containing protein of escherichia coli b. | highly purified iron superoxide dismutase was obtained from escherichia coli b using a modification of the procedure of yost and jridovich (yost, f. j., jr., and fridovich, i. (1973) j. biol. chem. 248, 4905-4908). the protein contained 1.8 +/- 0.2 atoms of iron per 38,700 g of protein. we have found that cyanide does not bind to the fe3+ ion of iron dismutase but fluoride and azide have moderately large binding constants. optical and electron paramagnetic resonance (epr) measurements suggested ... | 1976 | 184081 |
| regulation of carbohydrate permeases and adenylate cyclase in escherichia coli. studies with mutant strains in which enzyme i of the phosphoenolpyruvate:sugar phosphotransferase system is thermolabile. | carbohydrate uptake and cyclic adenosine 3':5'-monophosphate (cyclic amp) synthesis were studied employing mutant strains of escherichia coli in which enzyme i of the phosphoenolpyruvate:sugar phosphotransferase system was heat-labile. partial loss of enzyme i activity, which resulted from incubation of cells at the nonpermissive temperature, depressed the rate and extent of methyl alpha-glucoside uptake. temperature inactivation of enzyme i also rendered cyclic amp synthesis and the uptake of s ... | 1976 | 184083 |
| direct evidence for manganese (iii) binding to the manganosuperoxide dismutase of escherichia coli b. | | 1976 | 184095 |
| synthesis and biological properties of some spin-labeled 9-aminoacridines. | five spin-labeled 9-aminoacridines, each bearing either a 4-(2,2,6,6-tetramethyl-1-piperidinyloxy) or a 3-(2,2,5,5-tetramethyl-1-pyrrolidinyloxy) moiety in the 9 position, have been synthesized and assayed for biological activity in three different test systems. sedimentation velocity measurements indicated that the labels caused unwinding of calf thymus dna. those acridines which contained both 6-chloro and 2-methoxy substituents were less toxic to leukemia l1210 in static culture than the corr ... | 1976 | 184284 |
| methionine-repressible homoserine dehydrogenase of serratia marcescens: purification and properties. | serratia marcescens sa-3 possesses two homoserine dehydrogenases and neither has any aspartokinase activity unlike the case of escherichia coli enzymes. the two enzymes have been separated. one of them is active with either nad+ or nadp+ and has been purified about 180-fold to homogeneity. this enzyme is completely repressed by the presence of 1 mm methionine or homoserine in the growth medium, but its activity is unaffected by any amino acid of the aspartate family either singly or together. in ... | 1976 | 184374 |
| allosteric enzyme-trna complexes as regulators of transcription or translation. | the dehydrogenase activity of chorismate mutase-prephenate dehydrogenase, the allosteric enzyme of the tyrosine biosynthetic pathway in escherichia coli, is inhibited by trna. the inhibitory effect of trna from e. coli is specific, other rna species or polynucleotides have no inhibitory effect or only slightly influence the activity of the enzyme. while nad only slightly influences the inhibitory effect of trna from e. coli, prephenic acid at high concentrations suppresses the inhibition. in he ... | 1976 | 184692 |
| laboratory diagnosis of foodborne diseases. | many bacterial species are responsible for sporadic cases and outbreaks of foodborne intoxication and infection. the foodborne diseases are classified on the basis of the pathogenetic mechanisms involved into four categories: performed toxin, enterotoxin formed in the colonized small intestine, mucosal invasion (enterocolitis) and mucosal invasion with bacteremia. invasive and toxigenic strains of enteropathogenic escherichia coli are discussed. in vivo test systems for the identification of ent ... | 1976 | 184732 |
| purification and properties of guanosine 5', 3'-polyphosphate synthetase from bacillus brevis. | a ribosome-independent guanosine 5',3'-polyphosphate synthetase has been highly purified from bacillus brevis (atcc 8185). the enzyme has a molecular weight of 55,000, as measured by sucrose density gradient centrifugation. like the ribosome-connected stringent factor of escherichia coli, it catalyzes the synthesis of the guanosine 5', 3'-polyphosphates by a pyrophosphoryl transfer mechanism from adenosine triphosphate (atp) to guanosine di- or triphosphates (gdp, gtp). it has an apparent km of ... | 1976 | 184817 |
| [participation of 5'-deoxyadenosyl-b12 in regulating methylation of trna]. | the effects of different forms of cobalamines on the activities of trna-methylases of zajdela ascite hepatoma were studied. of six cobamides studied 5'-deoxyadenosyl-b12 and factor b containing as a ligand hso3 in the concentrations of 2.4-10(-5) and 4.8-10(-5) m inhibited the trna-methylase activity by 21% and 15% correspondingly. the inhibitory effect of 5'-deoxyadenosyl-b12 is probably dependent on the adenosyl part of the molecule. 5'deoxyadenosyl-b12 exerted a selective effect of zajdela a ... | 1976 | 184852 |
| leakage of periplasmic enzymes from lipopolysaccharide-defective mutants of salmonella typhimurium. | mutants of salmonella typhimurium with defects in the heptose region of the lipopolysaccharide (lps) molecule (heptose-deficient, chemotype re) leak periplasmic enzymes (acid phosphatase (ec 3.1.3.2), cyclic phosphodiesterase, ribonuclease i (ec 3.1.4.22), and phosphoglucose isomerase (ec 5.3.1.9) (pgi is at least partially periplasmic in e. coli and s. typhimurium; see below)) and do not leak an internal enzyme (glucose-6-phosphate dehydrogenase) into the growth medium. the extent of this leaka ... | 1976 | 184900 |
| chirality of the hydrogen transfer to the coenzyme catalyzed by ribitol dehydrogenase from klebsiella pneumoniae and d-mannitol 1-phosphate dehydrogenase from escherichia coli. | the stereochemistry of the hydrogen transfer to nad catalyzed by ribitol dehydrogenase (ribitol:nad 2-oxidoreductase, ec 1.1.1.56) from klebsiella pneumoniae and d-mannitol-1-phosphate dehydrogenase (d-mannitol-1-phosphate:nad 2-oxidoreductase, ec 1.1.1.17) from escherichia coli was investigated. [4-3h]nad was enzymatically reduced with nonlabelled ribitol in the presence of ribitol dehydrogenase and with nonlabelled d-mannitol 1-phosphate and d-mannitol 1-phosphate dehydrogenase, respectively. ... | 1976 | 185137 |
| mechanism of fever induction in rabbits. | three exogenous pyrogens (escherichia coli lipopolysaccharide, synthetic double-stranded ribonucleic acid. newcastle disease virus) were compared with respect to their mechanisms of fever induction in rabbits. all inducers stimulated the production of an endogenous pyrogen demonstrated in the blood as well as prostaglandins of the e group, and of cyclic adenosine 3',5'-monophosphate in the cerebrospinal fluid. the concentrations of these compounds were elevated approximately twofold as compared ... | 1976 | 185148 |
| stimulatory effect of lithium ion on proline transport by whole cells of escherichia coli. | the effect of monovalent cations on proline transport in whole cells of escherichia coli k-12 has been examined. lithium ion added to the uptake medium stimulated proline transport severalfold and k+ and na+ were slightly effective, whereas rb+, cs+, and nh4+ were completely without effect. the stimulatory effect of li+ on proline transport was not due to an increase in osmolarity of the uptake medium, and d 5 mm p-chloromercuribenzene sulfonic acid completely blocked this effect of li+ without ... | 1976 | 185195 |
| aminoacyl transfer rna formation. vii. lack of correlation between aminoacylation and ppi-atp exchange catalyzed by isoleucyl-trna synthetase of escherichia coli in the presence of various divalent cations. | isoleucyl-trna formation and isoleucine-dependent ppi-atp exchange catalyzed by purified isoleucyl-trna synthetase [ec 6.1.1.5] of escherichia coli were studied in the presence of various amounts of either mg2+, ca2+, fe2+, ni2+, or cu2+. in the presence of mg2+, isoleucine-dependent ppi-atp exchange was observed in parallel with isoleucyl-trna formation, while in the presence of ca2+, isoleucyl-trna formation was observed without isoleucine-dependent ppi-atp exchange. moreover, isoleucine-depen ... | 1976 | 185200 |
| escherichia coli acetate kinase mechanism studied by net initial rate, equilibrium, and independent isotopic exchange kinetics. | the equilibrium constant of the reaction catalyzed by acetate kinase (e.c. 2.7.2.1.) was determined: k = (mgadp) (acetylphosphate)/(mgatp)(acetate) = 6.7 +/- 1.3 x 10 (-4) (ph 7.4, 25 degrees). the respective free nucleotides uncomplexed to magnesium inhibit the net reaction in both directions: competitively with the respective magnesium nucleotide (mgatp or mgadp) and noncompetitively with the co-substrate (acetate or acetylphosphate). excess free magnesium also inhibits the net reaction in bot ... | 1976 | 185218 |
| inter- and intralaboratory variability in antibiotic susceptibility tests with pseudomonas aeruginosa and enterobacteriaceae. | a two-phase collaboratice study was designed for definition of the extent to which results of disk diffusion tests can be reproduced. two currently recommended techniques, the kirby-bauer method and the agar overlay method, were used. of special concern were tests of pseudomonas aeruginosa with moderate susceptibility to carbenicillin; gentamicin, tobramycin, polymyxin b, and colistin were also tested with p. aeruginosa as well as with klebsiella pneumoniae, escherichia coli, and proteus species ... | 1976 | 185302 |