Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| mutagenicity tests on anthelmintics: microsomal activation of viprynium embonate to a mutagen. | eight anthelmintic preparations readily available in australia were tested for mutagenicity in the salmonella typhimurium test system. a slightly modified version of the procedure recommended by ames et al. [2] was adopted, in that the test samples were placed in "wells" cut out of the agar of a plate previously seeded with the appropriate tester strain. addition of a mixture of rat liver microsomal enzymes and appropriate co-factors ("s-9 mix") to one of the two wells on a single plate allowed ... | 1977 | 327314 |
| mutagenic evaluation of nitrofuran derivatives in salmonella typhimurium, by the micronucleus test, and by in vivo cytogenetics. | 1977 | 327313 | |
| mutagenic activity of amino acid pyrolyzates in salmonella typhimurium ta 98. | pyrolyzates of 25 amino acids and 5 indole derivatives were tested for mutagenicity in the histidine-requiring mutant salmonella typhimurium ta 98. significant mutagenic activity was detected with pyrolyzates of most of the amino acids. these pyrolyzates required a liver microsomal fraction, as representative of mammalian metabolism, to be detected as mutagens. among the pyrolyzates tested, the highest mutagenic activity was observed with that of l-tryptophan. as little as 10 microgram of the py ... | 1977 | 327312 |
| mutagenic studies with acrylonitrile. | the mutagenicity of acrylonitrile (vinyl cyanide, propenenitrile) has been demonstrated in the ames salmonella typhimurium/liver microsome assay system. acrylonitrile, in the presence of a mouse liver homogenate produced mutations in the ta 1535, ta 1538 and ta 1978 strains. exposure of the bacteria was achieved by spotting the acrylonitrile on a "lawn" of salmonella, by shaking a reaction mixture consisting of bacteria, liver homogenate and acrylonitrile, and by exposing the homogenate and bact ... | 1977 | 327311 |
| detection of mutagenic activity in particulate air pollutants. | ames's strains of salmonella typhimurium were used to evaluate the mutagenic activity of airbone particulate materials collected at six different points in the industrial area of ohmuta and the residential area fukuoka. tests were done in presence of rat-liver s-9 fraction isolated from rats that had been treated with aroclor 1254. when the number of revertant colonies per plate was plotted against the amount of methanol extract of particulate air pollutants, using strain ta98, approximately lin ... | 1977 | 327308 |
| mutagenicity of anti-cancer nitrobenzofuroxans. | anti-leukaemically active benzofuroxans were tested for mutagenicity in salmonella typhimurium. mutagenicity was not found to be correlated to the previously established anti-leukaemic activity. one anti-leukaemically inactive compound after exposure to liver microsomal enzymes proved the most mutagenic of the derivatives for ta100, whereas after similar treatment, the mutagenicity of the most potent anti-leukaemic compound was reduced. all twelve derivatives tested were mutagenic in a base-subs ... | 1977 | 327305 |
| relative efficiencies of a series of square-planar plantinum(ii) compounds on salmonella mutagenesis. | twelve pt(ii) compounds have been tested for mutagenicity on salmonella typhimurium (strain ta 100). very high mutagenic activities were found for the cis derivatives. a correlation is suggested between these results and a formerly described model of chemical reactivity towards dna, according to which cis derivatives from intra-strand chelates with guanine. a smaller activity was found with monodentate complexes with dna. | 1977 | 327304 |
| the use of rec-bacteria for testing of carcinogenic substances. | a series of rec-escherichia coli strains were tested for their sensitivity to four known carcinogenic compounds by examination of a zone of inhibited bacterial growth around a central well containing the test chemical. the mutants reca-, recb-, recc-, and reca- recb- recc- were all more sensitive to the mutagens than the parental strain ab1157. the recb- recc- strain was examined with a larger series of compounds and was found to respond to many of the substances in a similar way as the salmonel ... | 1977 | 327303 |
| [pre-disposing factors and treatment problems in systemic invasion due to salmonella typhimurium in childhood]. | 1977 | 327297 | |
| detection of messenger rna from the isoleucine--valine operons of salmonella typhimurium by heterologous dna-rna hybridization: involvement of transfer rna in transcriptional repression. | a hybridization assay using escherichia coli k-12 dna isolated from the specialized transducing bacteriophage gammaci857st68h80 dilv was used to examine the rate of synthesis of the messenger rna's (mrna) derived from the isoleucine-valine (ilv) gene cluster of salmonella typhimurium. in all cases examined, changes in ilv enzyme levels could be correlated with changes in the rate of synthesis of ilv mrna. several well characterized regulatory mutants of s. typhimurium had rates of synthesis of ... | 1977 | 327261 |
| lipid a mutants of salmonella typhimurium. characterization of a conditional lethal mutant in 3-deoxy-d-mannooctulosonate-8-phosphate synthetase. | 1977 | 326782 | |
| regulation of l-cystine transport in salmonella typhimurium. | a kinetic analysis of l-cystine uptake in wild-type salmonella typhimurium indicates the presence of at least two, and possibly three, separate transport systems. cts-1 accounts for the majority of uptake at 20 mum l-cystine, with a vmax of 9.5 nmol/min per mg and a km of 2.0 mum; cts-2 is a low-capacity, higher-affinity system with a vmax of 0.22 nmol/min per mg and a km of 0.05 mum; a third, nonsaturable process has been designated cts-3. we find that wild-type cts-1 levels are at least 11 tim ... | 1977 | 326753 |
| susceptibility of lipopolysaccharide mutants to the bactericidal action of human neutrophil lysosomal fractions. | acetate extracts of purified human neutrophil granules (a mixed population containing specific and azurophil granules) were dialyzed against phosphate-buffered saline (ph 7.0) and tested for bactericidal activity against smooth parent and rough mutant, gram-negative bacteria. rough (re) mutants of escherichia coli, salmonella typhimurium, and salmonella minnesota were exquisitely more sensitive to extracts of human polymorphonuclear leukocyte granules than were their smooth (s) parents. the mean ... | 1977 | 326666 |
| use of enzyme-labeled antibodies to detect salmonella in foods. | an indirect enzyme-labeled antibody technique (elat), in which salmonella typhimurium was used as a model, was developed as a method to detect salmonella in food samples. a cellulose-acetate membrane filter, the matrix for detection, was placed on a membrane-filter base and overlaid with a multiwelled lucite template. mixed broth enrichment cultures were dispensed in the template wells, and cells were spotted onto the membrane via suction. after fixation, the membranes were immersed in rabbit an ... | 1977 | 326193 |
| toxicity and mutagenicity of hexavalent chromium on salmonella typhimurium. | four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the salmonella typhimurium/mammalian-microsome test. all hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 mug/plate, a significant increase of his(+) revertant colonies at doses ranging from 10 to 200 mug, and no effect at doses of less than 10 mug. the distinctive sensitivity of the four salmonella strains tested (ta1535, ta1537, ta98, and ta100 ... | 1977 | 326184 |
| [study of a "rfa" locus coding for cell wall lipopolysaccharide core biosynthesis in "shigella flexneri" f6s (author's transl)]. | the rfa-7 lipopolysaccharide core mutation carried by the r mutant f680, derived from shigella flexneri f6s serotype 5b, has been mapped by conjugation and transduction experiments. the results show a chromosomal distance of about 1 min between rfa-7 and mtl. such a position would be similar to those of rfa genes in escherichia coli k12 and salmonella typhi-murium lt2. conjugational transfer of e. coli k12 rfa+ genes to mutant f680 restored s. flexneri o-specificity. chemical analyses performed ... | 1977 | 326120 |
| [change in phagocytic activity toward the agent of tularemia in highly sensitive animals with mixed infections]. | an increase of the ingestive and digestive capacity of neutrophils to the homologous causative agent and tularemia microbe was revealed by the opsonophagocytic test in microtus arvalis, albino mice and guinea pigs infected with sublethal yersinia pseudotuberculosis and salmonella typhimurium doses. in subsequent tularemia infection some of the animals displayed a reduction of the septicemia intensity, prolongation of the disease and elevation of the susceptibility threshold. period of manifestat ... | 1977 | 325967 |
| fatal generalized bcg histiocytosis. | an infant was vaccinated at the age of 3 days with bcg vaccine. at the age of 3 years 10 months he developed an infection by salmonella typhimurium. the infection persisted with recurrent episodes of fever, peri-nephritic abscess, abscesses of lymph nodes, hepatomegaly, splenomegaly and paravertebral and retro-peritoneal abscesses, from which salmonella were isolated. at the age of 6 years and 2 months later. at post-mortem examination there were widespread histiocytic nodules in many organs, fr ... | 1977 | 325838 |
| use of a distant reporter group as evidence for a conformational change in a sensory receptor. | a highly sensitive method for demonstrating ligand-induced conformational changes in protein molecules in solution is described. the method utilizes an environmentally sensitive reporter group that is known to be distant from the active site. in the present application a conformational change is demonstrated in the galactose receptor of salmonella typhimurium, involved in bacterial sensing and transport, by means of an extrinsic fluorophore, 5-iodoacetamidofluorescein, attached at a single meth ... | 1977 | 325561 |
| a gene from escherichia coli affecting the sigma subunit of rna polymerase. | the rna polymerase sigma subunits of escherichia coli k, e. coli c, and salmonella typhimurium can be resolved by electrophoresis. using this technique, we have analyzed salmonella strains carrying f' plasmids from e. coli k in order to map the gene for the sigma factor. partial diploid analyses show the location of the sigma gene at 62-66 min on the e. coli genetic map. this gene is cotransducible with toic and dnag, at 66 min. | 1977 | 325556 |
| chromosomal location of a structural gene for the rna polymerase sigma factor in escherichia coli. | a set of f' strains of escherichia coli k-12 partially diploid for various chromosomal segments has been examined for possible gene dosage effects in the synthesis of sigma factor of the dna-dependent rna polymerase (rna nucleotidyltransferase; nucleoside-triphosphate:rna nucleoti-dyltransferase, ec 2.7.7.6). it was found that all f' strains diploid for the dnag region synthesize sigma at rates two to three times higher than other f' or f- strains. moreover, strains of salmonella typhimurium har ... | 1977 | 325555 |
| isolation, purification and properties of an intermediate in 3-deoxy-d-manno-octulosonic acid--lipid a biosynthesis. | incomplete lipid a has been purified from a mutant of salmonella typhimurium which is temperature-sensitive both in synthesis of 3-deoxy-d-manno-octulosonic acid 8-phosphate (docla-8-p) and in growth. pulse-chase experiments have shown that the incomplete lipid a molecule is the intermediate in the biosynthesis of the docla-lipid a portion of lipopolysaccharides. the purification procedure included deae-cellulose chromatography and electrodialysis. a highly water-soluble precursor material was o ... | 1977 | 324763 |
| mutagenicities of protein pyrolysates. | smoke condensate obtained by pyrolysis of proteins, such as lysozyme and histone, was shown to be mutagenic to salmonella typhimurium ta100 and ta98. in vitro metabolic activation by a mammaliam postmitochondrial enzyme preparation (s-9 mix) was required. smoke condensates obtained by pyrolysis of dna, rna, starch and vegetable oil were slightly mutagenic, whereas those from pyrolysis of l- and d-tryptophan and 5-hydroxy-d,l-tryptophan were very strongly mutagenic with metabolic activation by s- ... | 1977 | 324609 |
| inhibitory effects of selenium of the mutagenicity of 2-acetylaminofluorene (aaf) and aaf derivatives. | selenium (se) decreased the mutagenicity of 2-acetylaminofluorene (aaf), n-hydroxy-2-acetylaminofluorene (n-oh-aaf) and n-hydroxyaminofluorene (n-oh-af) in the salmonella typhimurium ta 1538 bacterial tester system. metabolism of aaf and n-oh-aff to the active mutagen, n-oh-af, was accomplished by rat liver extracts. graded decreases in mutagenicity with increasing se concentrations were observed for each of the three mutagens. se decreased the mutagenicity of aaf, n-oh-aaf and n-oh-af to 65, 68 ... | 1977 | 324608 |
| the mutagenicity of methylbenzylnitrosamine and its alpha-acetoxy derivatives. | biological activity of the alpha-acetoxy derivatives of methylbenzylnitrosamine was evaluated using tester strains of salmonella typhimurium. compound iii, oxidized on the benzyl moiety, was more toxic and more mutagenic than compound iv, oxidized on the methyl side chain. compound iv was weakly toxic and was non-mutagenic at the concentrations tested. the presence or absence of the uvrb repair system had no effect on the toxicity of either compound ii or iv. neither the alpha-oxidized compounds ... | 1977 | 324607 |
| reiter's disease after salmonella typhimurium enteritis. | 1977 | 324575 | |
| studies on the mutagenicity of nitrofurans in salmonella typhimurium. | 1977 | 324478 | |
| prevention of salmonella typhimurium infection inpoultry by pretreatment of chickens and poults with intestinal extracts. | day-old chickens or turkey poults when pretreated with an oral dose of intestinal fluid froma healthy adult bird, were considerably more resistant to the subsequent establishment of salmonella typhimurium in their intestinal tract than were non-treated chickens or turkey poults. caecal fluid was more effective as a pretreatment than were washings taken from other parts of the gastro-intestinal tract of a healthy adult bird. this increased resistance of pretreated chickens or poults is thought to ... | 1977 | 324465 |
| mutagenic activity of nitrite-treated foods: human stomach cancer may be related to dietary factors. | by the salmonella typhimurium test, extracts of japanese raw fish treated in the laboratory with nitrite showed mutagenic activity which is prevented by addition of ascorbate. extracts from similarly treated beef and hot dogs were nonmutagenic. the data conform to a working concept that the high stomach cancer incidence in japanese and certain other populations may be due to specific dietary factors of an alkylnitrosamide type. | 1977 | 323974 |
| inhibition of histidyl-trna-adenosine triphosphate phosphoribosyltransferase complex formation by histidine and by guanosine tetraphosphate. | formation of the complex between the first enzyme of histidine biosynthesis from salmonella typhimurium, atp phosphoribosyltransferase [1-(5'-phosphoribosyl)-atp: pyrophosphate phosphoribosyltransferase; ec 2.4.2.17], and histidyl-trna is shown to be inhibited by l-histidine and by guanosine-5'-diphosphate-3'-diphosphate in the presence of histidine. higher histodine levels make guanosine tetraphosphate a more effective inhibitor. relatively high concentrations of guanosine-5'-triphosphate also ... | 1977 | 323857 |
| mutagenicities of quinoline and its derivatives. | quinoline, recently reported to be carcinogenic in rats [12], was mutagenic to salmonella typhimurium tester strains ta100 and ta98 in the presence of the metabolic activation system s-9 mix. 2-chloroquinoline, a non-carcinogen [12], was non-mutagenic with or without s-9 mix. 8-hydroxyquinoline, which is t known to be carcinogenic, was mutagenic with s-9 mix to both bacterial strains. the mutagenicities of 17 other quinoline derivatives that are not known to be carcinogenic were tested, and 12 o ... | 1977 | 323699 |
| membrane fluidity and chemotaxis: effects of temperature and membrane lipid composition on the swimming behavior of salmonella typhimurium and escherichia coli. | 1977 | 323503 | |
| protective effects of passively transferred immune t- or b-lymphocytes in mice infected with salmonella typhimurium. | purified populations of bone marrow-derived (b-) lymphocytes and thymus-derived (t-) lymphocytes were obtained from c3d2f1 hybrid mice shown to be immune to salmonella typhimurium. these subpopulations of lymphocytes were injected into normal mice; four days later the animals were challenged with 50 50% lethal doses of s. typhimurium, and viable bacteria in livers, spleens, and blood were counted at various intervals after challenge. on day 8 after challenge, the mice supplemented with b-lymphoc ... | 1977 | 323381 |
| identification of a gamma-glutamyl methyl ester in bacterial membrane protein involved in chemotaxis. | evidence is presented that a methyltransferase enzyme, previously shown to be necessary for chemotaxis and identified as the cher gene product, catalyzes the formation of a gamma-glutamyl methyl ester in one or more membrane proteins of salmonella typhimurium. the rates of release of methyl label from the methylated protein in acid, base, and hydroxylamine are consistent with a methyl ester and not with a methylated imidazole, guanidino, or amino group. a gamma-glutamyl methyl ester was isolated ... | 1977 | 323255 |
| degradation of escherichia coli beta-galactosidase fragments in protease-deficient mutants of salmonella typhimurium. | the degradation rates of several mutationally generated fragments of escherichia coli beta-galactosidase were determined in wild-type strains of salmonella typhimurium and in mutant salmonella strains lacking several proteases and peptidases. three termination fragments (produced by lacz545, lacz521, and laczx90) and one internal reinitiation (restart) fragment [laczpi(1)] are degraded in wild-type salmonella strains at the same rates observed in wild-type escherichia coli strains. mutations tha ... | 1977 | 323234 |
| chemotactic mechanism of salmonella typhimurium: preliminary mapping and characterization of mutants. | some new, generally nonchemotactic mutants of salmonella typhimurium were isolated and they, together with previously isolated mutants and some from other investigators, were mapped. most of the mutants were classified in nine complementation groups, which are probably individual genes. of these, five map at the end of the flagella region and appear in the order motb-(chewchep)-chex-cheq-cher-flac. two of the mutations, cheu and chev, map in the flaq and flaaii genes, respectively. the remaining ... | 1977 | 323229 |
| role of zinc in the abatement of hepatocellular damage and mortality incidence in endotoxemic rats. | intraperitoneal administration of zinc (znip) as zinc chloride prior to or simultaneously with a lethal quantity of intraperitoneally administered salmonella typhimurium endotoxin significantly protected rats against toxin-induced mortality and hepatocellular damage. pretreatment with amounts of zinc chloride ranging from 0.4 to 2.0 mg/100 g of body weight resulted in 80 to 100% survival compared with 10% survival in untreated control rats at 24 h after endotoxin treatment. zinc chloride treatme ... | 1977 | 323146 |
| isolation of the glucuronic acid conjugate of n-hydroxy-4-aminobiphenyl from dog urine and its mutagenic activity. | the glucuronic acid conjugate of n-hydroxy-4-aminobiphenyl (noh-4-abp) has been isolated in relatively pure form from the urine of dogs given 4-aminobiphenyl, utilizing molecular size, ion exchange, adsorption, and partition chromatography. this conjugate is an active mutagen in salmonella typhimurium strains ta1538 and ta98 but not in ta1535 or ta1537. noh-4-abp and 4-nitrosobiphenyl are also highly active in ta1538 and ta98 and inactive in ta1535 and ta1537. these observations support the conc ... | 1977 | 322861 |
| comparative electrophilicity, mutagenicity, dna repair induction activity, and carcinogenicity of some n- and o-acyl derivatives of n-hydroxy-2-aminoflourene. | n-myristoyloxy-n-acetyl-2-aminofluorene, n-acetoxy-n-myristoyl-2-aminofluorene, n-myristoyloxy-n-myristoyl-2-aminofluorene, and n-hydroxy-n-myristoyl-2-aminofluorene each yielded a high incidence of sarcomas in male rats within 5 to 7 months after s.c. injection of 64 micronmoles in divided doses. n-acetoxy-n-acetyl-2-aminofluorene and n-hydroxy-2-acetylaminofluorene, although potent carcinogens at the s.c. site, were less active than the above derivatives with a myristoyl substituent. n-sulfono ... | 1977 | 322856 |
| generalized indicator plate for genetic, metabolic, and taxonomic studies with microorganisms. | we have developed an indicator plate that works well for diverse types of substrates and microorganisms. the plates are inexpensive and easy to prepare. the essential components are agar, buffer, growth-supporting nutrients, a test substrate, and 2,3,5-triphenyl tetrazolium chloride (ttc). using various strains of salmonella typhimurium and escherichia coli, we have studied and defined the contribution of each component to the satisfactory function of the plate. colonies capable of catabolizing ... | 1977 | 322611 |
| effects of crowding of mice on humoral antibody formation and protection to lethal antigenic challenge. | the effects of grouping (crowding) on humoral antibody response to typhoid paratyphoid vaccine and subsequent protection from a minimal lethal challenge dose of salmonella typhimurium were studied in white swiss-webster mice. the data show a trend between the degree of crowding and antibody response. geometric mean titers of high density grouped mice were significantly lower than the geometric mean titers of the less crowded mice. also, there were significantly less antibody responders in the hi ... | 1977 | 322186 |
| identification of a protein methyltransferase as the cher gene product in the bacterial sensing system. | methylation of membrane-bound proteins with apparent molecular weights around 65,000 does not occur in mutants of the generally nonchemotactic cher class of salmonella typhimurium. this was shown to be due to the lack of a protein methyltransferase in these mutants by means of an in vitro assay using soluble proteins, membranes, and s-adenosylmethionine as the methyl donor. the methylase from the wild type was purified, characterized, and shown to be of molecular weight 38,000. it is specific fo ... | 1977 | 322131 |
| localization of pfl gene by transductional study of the gal-aro a segment of the salmonella typhimurium lt2 chromosome. | 1977 | 321941 | |
| regulation of bacteriophage p22 dna synthesis and repressor levels in p22cly infections. | a rifampin-resistant mutant of salmonella typhimurium carries an altered rna polymerase. wild-type (c+) phage p22 displays clear plaques and a reduced lysogenization frequency on this mutant host. the cly mutants of p22 were isolated on the basis of their ability to lysogenize such mutant hosts. two classes of regulatory events, both of which are dependent on p22 gene c1 activity, are necessary for the establishment of lysogeny in p22. the positive events culminate in repressor synthesis; the ne ... | 1977 | 321806 |
| mutagenicity for salmonella typhimurium of urine obtained from humans receiving nitrofurantoin. | urine samples from 12 humans receiving oral therapeutic doses of nitrofurantoin were mutagenic for salmonella typhimurium strain ta 100 and nonmutagenic for strain ta 100-fr1. mutagenic activity of the urine was not increased by treatment with beta-glucuronidase. spot mutation assay of the chromatogram of urine revealed that the mutagenic activity of the urine was mainly due to unmetabolized nitrofurantoin. | 1977 | 321796 |
| bacteriophage-typing designations of salmonella typhimurium. | the phage-typing scheme of callow (1959) has been extended. the original number of types was 34; this has now risen to 207. tables are presented which show the provisional type designations and the definitive designations now being introduced. | 1977 | 321679 |
| physical characterization of a plasmid cointegrate containing an f'his gnd element and the salmonella typhimurium lt2 cryptic plasmid. | a recombinant plasmid (pas19) isolated from a derivative of salmonella typhimurium lt2, containing the strain lt2 cryptic plasmid and an f'his gnd element, has been physically characterized. the pas19 plasmid contour length equals the sum of the contour lengths of the cryptic plasmid and f'his gnd element. deoxyribonucleic acid (dna)-dna hybridization experiments demonstrated that whereas the pas19 plasmid exhibits extensive dna homology with both the cryptic plasmid and the f'his gnd element, t ... | 1977 | 321435 |
| fine-structure map of the histidine transport genes in salmonella typhimurium. | afine-structure genetic map of the histidine transport region of the salmonella typhimurium chromosome was constructed. twenty-five deletion mutants were isolated and used for dividing the hisj and hisp genes into 8 and 13 regions respectively. a total of 308 mutations, spontaneous and mutagen induced, have been placed in these regions by deletion mapping. the histidine transport operon is presumed to be constituted of genes dhua, hisj, and hisp, and the regulation of the hosp and hisj genes by ... | 1977 | 321422 |
| comparison of the virulence of o:9,12 and o:4,5,12 salmonella typhimurium his+ transductants for mice. | the purpose of these experiments was to determine whether qualitative differences in the o repeat unit of the lipopolysaccharide of pathogenic salmonella species affected virulence for mice. o:4,5,12 and o:9,12 sister his+ transductants were derived from a virulent salmonella typhimurium. fermentation markers were introduced by transduction to differentiate these strains, and the strains were used as mixed challenge to cf1 and c57b1/6j mice. liver and spleen cultures of the mice of various inter ... | 1977 | 321351 |
| physiochemical consequences of opsonization of salmonella typhimurium with hyperimmune igg and complement. | partition in an aqueous, two-polymer phase system containing dextran and polyethylene glycol was employed to investigate the physico-chemical changes inflicted upon the cell surface of a smooth strain of salmonella typhimurium by the binding of antibody igg and complement. the minimum antibody concentration for increased phagocytosis in vitro was approximately the same as that for a significant change in two-phase partition, ca 8000 mol/bacterium, whereas a lower concentration, less than 4000 mo ... | 1977 | 321337 |
| the origin of the sulfur atom in thiamine. | the mode of biosynthesis of the thiazole moiety of thiamine, 4-methyl-5beta-hydroxyethyl thiazole (mhet) was studied using salmonella typhimurium as test organism. it was shown by isotope incorporation experiments, that the sulfur atom, but not carbon-3, of cysteine is incorporated into mhet, indicating a separation of the sulfur atom of cysteine from the carbon chain during incorporation. isotope competition experiments revealed that the incorporation of [35s]cysteine is not significantly dilut ... | 1977 | 321036 |
| partial derepression of the isoleucine-valine enzymes during methionine starvation is salmonella typhimurium. | methionine starvation of methionine auxotrophs in the presence of excess branched-chain amino acids results in a partial derepression of the isoleucine and valine enzymes. reversed-phase chromatography indicated that isoleucine, valine and leucine trna were altered during methionine starvation. in addition, the total trna isolated from cells under these conditions were undermethylated. the observed derepression may be caused by the inability of methyl-deficient trna's to participate adequately i ... | 1977 | 321028 |
| nuclear magnetic resonance and fluorescence studies of substrate-induced conformational changes of histidine-binding protein j of salmonella typhimurium. | the histidine-binding protein j of salmonella typhimurium binds l-histidine as a first step in the high-affinity active transport of this amino acid across the cytoplasmic membrane. high-resolution nuclear magnetic resonance spectroscopy has been used to monitor the conformation of histidine-binding protein j in the presence and absence of substrate. evidence is presented to show that this binding protein undergoes a conformational change involving a substantial number of amino-acid residues (in ... | 1977 | 321019 |
| [epidemiologic relationship of infections with salmonella typhimurium in switzerland studied by phage typing (author's transl)]. | in the area, controlled by the institute of microbiology of st. gall, 262 s. typhi murium strains could be isolated during 1973. by means of phage typing, according to guinee, 20 different phage types as well as 6 additional atypically reacting strains, with characteristic atypical pattern, were recognized. the phage type 650 was most frequently encountered (37.0%) folowed by types 61 (20.2%) and 505 (10.3%). an intensive change in phage types was noted among 114 cases, observed over 7 months, i ... | 1977 | 320792 |
| [drug resistance of phage types of salmonella typhimurium (author's transl)]. | antimicrobial susceptibility testing (disk diffusion test) and phage typing (method according to anderson, performed by prof. brandis, bonn) of 703 strains of salmonella typhimurium from humans, isolated in essen and surrounding during 1972 to 1975, was performed to dertermine whether characteristic patterns of drug resistance were associated with a single phage type or not. the most frequently isolated phage types are phage type 17 (12.2%), 12 (10.1%), 49 (8.1%), 15a (5.7%), 2 (3,3%) and the un ... | 1977 | 320791 |
| [spondylitis caused by salmonella typhimurium (author's transl)]. | described is a case of spondylitis caused by salmonella typhimurium. according to literature osteomyelitis and spondylitis are rare as local manifestation of a salmonella infection. spondylitis caused by salmonella typhimurium, the most common species, is almost unknown. the problems in diagnosis and therapy are discussed. | 1977 | 320772 |
| comparative mutagenicity of icr-191 to s. typhimurium and diploid human lymphoblasts. | concentration-dependent mutagenicity of icr-191 has been measured in salmonella typhimurium strain ta98 and in a diploid human cell line. in both cell systems, approximately equigenerational exposure produced mutation linearly related to concentration in the lower range of icr-191 concentrations tested. saturation behavior was observed in the human cell assay but not in the bacterial assay. however, a 25-fold greater concentration of icr-191 was required to induce a significant rise in the mutan ... | 1977 | 320468 |
| 9-aminoacridine-a frameshift mutagen for salmonella typhimurium ta 1537 inactive at the hgprt locus in human lymphoblasts. | 1977 | 320466 | |
| isolation and characterization of catalase deficient mutants of salmonella typhimurium. | catalase deficient mutants (kat) of salmonella typhimurium have been isolated. the mutantions kata1, katc6 and katd9 appear to map at about minute 10 on the salmonella chromosome. the katc6 and katd9 lesions are complemented by the e. coli f'128 (lac + pro +) episome but the kata1 lesion is not. katb2 maps at about minute 100. none of the mutants are oxygen sensitive; they grow as well as wild bacteria, even when aerated. | 1977 | 320456 |
| influence of methionine biosynthesis on serine transhydroxymethylase regulation in salmonella typhimurium lt2. | the enzyme serine transhydroxymethylase (ec 2.1.2.1; l-serine:tetrahydrofolate-5,10-hydroxymethyltransferase) is responsible both for the synthesis of glycine from serine and production of the 5,10-methylenetetrahydrofolate necessary as a methyl donor for methionine synthesis. two mutants selected for alteration in serine transhydroxymethylase regulation also have phenotypes characteristic of metk (methionine regulatory) mutants, including ethionine, norleucine, and alpha-methylmethionine resist ... | 1977 | 320194 |
| repression and inhibition of transport systems for branched-chain amino acids in salmonella typhimurium. | kinetics of the transport systems common for entry of l-isoleucine, l-leucine, and l-valine in salmonella typhimurium lt2 have been analyzed as a function of substrateconcentration in the range of 0.5 to 45 mum. the systems of transport mutants, ka203 (ilvt3) and ka204 (ilvt4), are composed of two components; apparent km values for uptake of isoleucine, leucine, and valine by the low km component are 2 mum, 2 to 3 mum, and 1 mum, respectively, and by the high km component 30 mum, 20 to 40 mum, a ... | 1977 | 320186 |
| outer membrane of salmonella typhimurium. identification of proteins exposed on cell surface. | proteins exposed on the outer surface of the outer membrane of salmonella typhimurium were identified by reacting intact cells with a covalent labeling reagent. since the outer membrane permitted the free diffusion of small hydrophilic molecules, we used a macromolecular reagent, cnbr-activated dextran, as the non-penetrating labeling agent. we also used a mutant producing a lipopolysaccharide with a very short (i.e. hexasaccharide) carbohydrate chain, in order to avoid steric hindrance by the c ... | 1977 | 319828 |
| properties of the galactose binding protein of salmonella typhimurium and escherichia coli. | the galactose binding protein implicated in transport and in chemotaxis has been purified to homogeneity from the shock fluids of salmonella typhimurium and escherichia coli. both proteins are monomers of molecular weight 33 000 and exhibit cross-reactivity with antibody. the salmonella galactose receptor showed binding of 1 mol of [14c]galactose or 1 mol of [14c]glucose at saturation. the dissociation constants were 0.38 and 0.17 mum, respectively. in light of the previously published report th ... | 1977 | 319823 |
| salmonella typhimurium/enzymol. | 1977 | 319757 | |
| bactericidal effects of combinations of ampicillin with anti-r-plasmid compounds on salmonella typhimurium r1+. | salmonella typhimurium r1(+), resistant to 2,500 mug of ampicillin per ml, was rapidly killed by combinations of 60 mug of ampicillin per ml with quinacrine (4 x 10(-4) m), ethidium bromide (10(-4) m), tilorone (10(-4) m), or nitroakridin 3582 (5 x 10(-6) m). | 1977 | 319749 |
| factors affecting mutagenic activity of cigarette smoke condensate in salmonella typhimurium ta 1538. | smoke condensates from burley tobacco, bright-type tobacco and various brands of commercial cigarettes were tested for mutagenicity by using a microsomal test system with salmonella typhimurium ta 1538. smoke condensate from burley tobacco had much higher mutagenic activity than that from bright-type tobacco. increased mutagenic activity was observed with smoke condensates from burley tobacco grown with increasing amounts of nitrogen fertilizer, and from commercial cigarettes blended with burley ... | 1977 | 319352 |
| studies on mutagenicity of irradiated sugar solutions in salmonella typhimurium. | irradiated sugar solutions are mutagenic towards salmonella typhimurium, the effect being dose-dependent up to 2.0 mrad. at all doses, ribose solution exhibited greater mutagenicity than did sucrose solution. the mutagenic effect was observed only in dividing cells and appears to be directly related to the growth rate. a larger proportion of revertants was observed after incubation with irradiated sugar solution for a period of 4 h than for 24 h. irradiation of the sugar solutions in the frozen ... | 1977 | 319351 |
| in vitro metabolic activation of ethidium bromide and other phenanthridinium compounds: mutagenic activity in salmonella typhimurium. | 1977 | 319349 | |
| patterns of transcription in bacteriophage p22-infected salmonella typhimurium. | two peaks of rna synthesis (early and late) are directed by bacteriophage p22 in lytic infections of salmonella typhimurium. late rna synthesis is not seen in p22 23- infections; neither early nor late rna synthesis occurs in p22 24- infections. genes 23 and 24 of p22 appear to be analogous to genes q and n of lambda, respectively. | 1977 | 319258 |
| airborne mutagens bioassayed in salmonella typhimurium. | particulate airborne pollutants, collected in buffalo, new york, and berkeley, california, were asayed for mutagenic activity in the ames salmonella typhimurium test system. mutagens requiring liver enzymes for activation, as well as direct acting mutagens, were readily detected in the buffalo sample. by contrast, only direct acting mutagens were detected in the berkeley sample. | 1977 | 319246 |
| mutagenicity of five cyclic n-nitrosamines: assay with salmonella typhimurium. | the mutagenicity of five cyclic n-nitrosamines was studied with the use of salmonella typhimurium ta1535 in vitro with and without microsomal activation. the carcinogens nitrosopiperidine and nitrosopyrrolidine required metabolic activation before manifesting mutagenic activity. nitrosoproline and nitrosohydroxyproline, noncarcinogens, were not mutagenic. nitroso-3-pyrrolidinol was mutagenic in the absence of microsomes, thereby suggesting a role of hydroxylation in the metabolic activation of n ... | 1977 | 319245 |
| mutagenic activities in vitro and in vivo of five antischistosomal compounds. | five antischistosomal compounds--hycanthone, two of its chloroindazole analogs (ia-4 and ia-4 n-oxide), oxamniquine, and metrifonate--were tested for mutagenic activity, using salmonella typhimurium strains ta 98 and ta 100 under in vitro and in vivo (host-mediated) conditions. in all assay systems hycanthone exhibited by far the highest mutagenic potency. although oxamniquine and metrifonate had low metagenic activity in vitro and although their administration resulted in urine of low metagenic ... | 1977 | 319220 |
| mitogenic stimulation of murine spleen cells: relation to susceptibility to salmonella infection. | the screening of several inbred strains of mice suggested that the capacity of their spleen cells to respond to the mitogenic effect of lipopolysaccharide (lps) of gram-negative bacteria was correlated with their resistance to intraperitoneal infection with salmonella typhimurium. an infection of lps into mice caused changes in the in vitro responsiveness of their spleen cells to the mitogenic effects of lps and phytohemagglutinin. pretreatment of mice with whole ultraviolet (uv)-killed bacteria ... | 1977 | 319060 |
| formate hydrogenlyase system in salmonella typhimurium lt2. | isolation from salmonella typhimurium of mutants unable to reduce benzyl viologen under anaerobic conditions has allowed the study of the factors involved in the multienzymic formate hydrogenylase system. 1. depending on the affected activities, different classes of mutants were found: fhl-a mutants have lost formate dehydrogenase 1 and formate dehydrogenase 2 activities; mutations in fdha (117 min) or fdhb (33 min) lead to such a phenotype. fhl-b and fhl-c mutants have lost formate dehydrogenas ... | 1977 | 318997 |
| the contribution of metronidazole and two metabolites to the mutagenic activity detected in urine of treated humans and mice. | the urine of two patients receiving therapeutic doses of the trichomonacide, metronidazole, was analyzed for mutagenic activity using the histidine auxotroph ta1535 of salmonella typhimurium. the activity detected in the urine was significantly higher than could be accounted for by the presence of the administered drug. chromatographic analysis of the urine indicated the presence of the metabolite 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole, which when tested in vitro with ta1535 was fou ... | 1977 | 318924 |
| the effects of additional flora on the response of salmonella mutants lodged in the gastrointestinal tract. | a histidine auxotroph of salmonella typhimurium, strain ta1538, will lodge for several months in the gastrointestinal tract of otherwise germ-free rats and of rats additionally associated with bacteria characteristic of the normal flora such as lactobacillus plantarum and bacteroides vulgatus. in the presence of the additional flora, the concentration of strain ta1538 is diminished in the stomach but not in the lower gastrointestinal tract or in the feces. following the ingestion of 2-nitrofluor ... | 1977 | 318921 |
| mutagenicity of n-butyl-n-(4-hydroxybutyl)nitrosamine, a bladder carcinogen, and related compounds. | n-butyl-n-(4-hydroxybutyl)nitrosamine (bbn), which specifically induces bladder tumors, was shown to be mutagenic to salmonella typhimurium strains ta 1535 and ta100 in the presence of an s-9 mix prepared from the liver of rats treated with polychlorinated biphenyl. reduced nicotinamide adenine dinucleotide was a more effective cofactor than reduced nicotinamide adenine dinucleotide phosphate in the activation of bbn by the rat liver s-9 fraction, n-butyl-n-(3-carboxypropyl)nitrosamine, reported ... | 1977 | 318920 |
| antimicrobial susceptibility of salmonella isolates from the broiler chicken industry in ontario. | antibacterial drug resistance among 219 salmonella isolates recovered during 1974 from poultry and poultry environments at the various production stages of broiler chickens in three integrated ontario companies are recorded. all isolates were susceptible to ampicillin, trimethroprim-sulfamethoxazole complex, furazolidone, cephaloridine and amoxicillin. a relative increase in resistance to tetracycline and streptomycin with an accompanying decrease in resistance to triple sulfa compound was recor ... | 1977 | 318909 |
| tris(2,3-dibromopropyl) phosphate: mutagenicity of a widely used flame retardant. | tris(2,3-dibromopropyl) phosphate, a widely used flame-retardant additive for textiles, is mutagenic to histidine-requiring strains of salmonella typhimurium. extracts of fabrics treated with this compound are also capable of inducing mutations in these bacterial strains. | 1977 | 318761 |
| mitomycin c-induced expression of trpa of salmonella typhimurium inserted into the plasmid cole1. | ecori endonuclease digestion of the deoxyribonucleic acid of a phi80 transducing phage carrying the entire tryptophan (trp) operon of salmonella typhimurium (phi80 s.t.trpe-a) yielded a 4.3 x 10(6)-dalton fragment containing intact trpe, trpd, and trpc and a 3.35 x 10(6)-dalton fragment containing intact trpa. the trpa fragment inserted into ecori-cleaved plasmids cole1 and cr1 was expressed regardless of its orientation of insertion. mitomycin c, a compound that induces colicin e1 production in ... | 1977 | 318646 |
| thymidine-requiring mutants of salmonella typhimurium that are defective in deoxyuridine 5'-phosphate synthesis. | in a salmonella typhimurium strain made diploid for the thy region by introduction of the escherichia coli episome, f'15, mutants resistant to trimethoprim in the presence of thymidine were selected. one was shown to be defective in deoxyuridine 5'-phosphate (dump) synthesis; it requires deoxyuridine or thymidine for growth and is sensitive to trimethoprim in the presence of deoxyuridine. genetic studies showed that the mutant is mutated in two genes, dcd and dum, located at 70 and 18 min, respe ... | 1977 | 318643 |
| chemical composition and biological activities of a phenol-water extract from haemophilus influenzae type a. | ribonucleic acid was removed from a phenol-water extract of haemophilus influenzae type a by streptomycin sulfate. this preparation was called purified preparation or pp. it contained neutral sugars (glucose, galactose, mannose, pentose), glucosamine, amino acids, and fatty acids. heptose and 2-keto-3-deoxyoctonic acid were not present. the biological properties and immunogenicity were compared with the activities of lipopolysaccharide of escherichia coli or salmonella typhimurium. higher doses ... | 1979 | 317593 |
| nitrous acid mutagenesis of duplex dna as a three-component system. | purified native hemophilus influenzae dna is relatively insusceptible to nitrous acid (na) mutagenesis in vitro, but is readily mutated following denaturation. na mutagenicity for duplex dna is significantly increased in the presence of various alcohols, glycols, phenols or primary amines. phenol-extracted dna contains dissociable contaminants of low molecular weight that enhance na mutagenesis. enhancement of na mutagenesis by phenol and by spermine is due to the formation of unstable molecular ... | 1979 | 314585 |
| mechanism for induction of anti-dna antibodies by bacterial lipopolysaccharides in mice; ii. correlation between anti-dna induction and polyclonal antibody formation by various polyclonal b lymphocyte activators. | the capacity of various polyclonal b lymphocyte activators (pba) to induce, in mice, the formation of anti-dna antibodies was compared with their ability to mediate the release of dna in circulating blood and to stimulate polyclonal antibody synthesis in vivo. anti-dna antibodies or polyclonal antibody synthesis were induced in mice after the injection of at least 10 microgram lipopolysaccaride (lps) from salmonella typhimurium, 1 mg dextran sulfate (ds), or 2 mg purified protein derivative of t ... | 1977 | 303258 |
| pyrolysis products from amino acids and protein: highest mutagenicity requires cytochrome p1-450. | pyrolysis products of proteins and amino acids are highly mutagenic, but metabolism of these chemicals by rat liver subcellular fractions is known to be required for production of the mutagenic intermediates. we examined the mutagenesis of seven purified pyrolysis products from tryptophan, lysine, glutamic acid, and soybean globulin with salmonella typhimurium strain ta98 in the presence of liver fractions from genetically "responsive" c57bl/6n and ah(b)/ah(d) or "nonresponsive" dba/2n and ah(d) ... | 1979 | 293693 |
| inhibition of promutagen activation by the antioxidants butylated hydroxyanisole and butylated hydroxytoluene. | butylated hydroxyanisole (bha) and butylated hydroxytoluene (bht) exhibited antimutagenic activity in the salmonella typhimurium reversion test. both bha and bht reduced reversion induced by chemicals requiring metabolic activation for effectiveness. however, they did not affect reversion induced by direct-acting mutagens. these results suggested that bha and bht may inhibit the metabolic activation processes and demonstrated that the s. typhimurium reversion test may be used to identify inhibit ... | 1979 | 287836 |
| carcinogenicity test of six nitrosamides and a nitrosocyanamide administered orally to rats. | six nitrosamides [ethylnitrosourea (enu), 2-hydroxyethylnitrosourea (henu), carboxymethylnitrosourea, 1-nitroso-5,6-dihydrouracil (ndhu), 1-nitrosohydantoin, and n-methyl-n-nitrosobenzamide (mnb)] and ethylnitrosocyanamide (enc) were administered chronically in sodium citrate-buffered drinking water to mrc wistar rats. enu induced tumors of the reticuloendothelial system (res) (50% incidence), mammary glands, and large intestine. ndhu in drinking water produced hepatocellular carcinomas (96% inc ... | 1979 | 286123 |
| transposition of plasmid dna segments specifying hydrocarbon degradation and their expression in various microorganisms. | the conjugative tol plasmid (75 mdal), specifying biodegradation of xylenes, toluene, and trimethylbenzene derivatives, undergoes dissociation in pseudomonas aeruginosa pao to a nonconjugative tol(*) plasmid (28 mdal) and a transfer plasmid termed toldelta (48 mdal). the tol(*) plasmid is rendered transmissible through introduction of a number of conjugative plasmids such as factor k, cam, and toldelta but not by the fp2 derivative pr0271. transfer of tol(*) via factor k or toldelta is mediated ... | 1978 | 277912 |
| [study of the mutagenic activity of mazheptil]. | mutagenic activity of the psychotropid drug--majeptil was studied. majeptil does not induce gene mutations on salmonella typhimurium and chromosomal aberrations in mice bone marrow cells in vivo. it is shown that majeptil increase the level of chromosome aberrations in the culture of human peripheral blood lymphocytes. it is also active in the dominant lethal test on mice. | 1975 | 241146 |
| regulation of the ammonia assimilatory enzymes in salmonella typhimurium. | the regulation of glutamate dehydrogenase (ec 1.4.1.4), glutamine synthetase (ec 6.3.1.2), and glutamate synthase (ec 2.6.1.53) was examined for cultures of salmonella typhimurium grown with various nitrogen and amino acid sources. in contrast to the regulatory pattern observed in klebsiella aerogenes, the glutamate dehydrogenase levels of s. typhimurium do not decrease when glutamine synthetase is derepressed during growth with limiting ammonia. thus, it appears that the s. typhimurium glutamin ... | 1975 | 240804 |
| soluble and membrane-bound aspartate-binding activities in salmonella typhimurium. | the specificities of the soluble and membrane aspartate-binding activities were compared with each other and with the specificity of aspartate chemotaxis and were found to be distinct. the soluble aspartate-binding protein was purified to homogeneity and had a molecular weight of 30,000. the dissociation constant was 10(-6) m for aspartate, and the protein bound glutamate, cysteic acid, and 2-amino-3-phosphonopropionate. aspartate transport was inhibited by cysteic acid. | 1975 | 239919 |
| a transport system for phosphoenolpyruvate, 2-phosphoglycerate, and 3-phosphoglycerate in salmonella typhimurium. | salmonella typhimurium strain lt-2 was found to utilize phosphoenolpyruvate, 2-phosphoglycerate, and 3-phosphoglycerate as sole sources of carbon and energy for growth, but escherichia coli strains did not. the following evidence suggests that this growth difference was due to the presence in salmonella cells of an inducible phosphoglycerate permease distinct from previously studied transport systems: (a) the ability of cells to take up 3-phospho[14-c]glycerate was induced by growth in the prese ... | 1975 | 238977 |
| regulation of catalase synthesis in salmonella typhimurium. | the specific activity of catalase in salmonella typhimurium and other enteric bacteria decreased during the logarithmic phase of growth and increased at the onset and during the stationary phase. the increase in catalase synthesis at the end of the exponential phase in s. typhimurium cells coincided with the lowest ph value reached by the culture. maintenance of the ph at a constant neutral value did not alter the typical pattern of synthesis in contradiction of the results previously reported ( ... | 1975 | 238955 |
| gene order of the histidine utilization (hut) operons in klebsiella aerogenes. | p1-sensitive mutants of klebsiella aerogenes were isolated and the gene order of the hut region was then determined using p1-mediated transduction. the genes are located in the klebsiella chromosome between gal and bio as in salmonella typhimurium. the gene order, gal, huti, hutg, hutc, huu, huth, bio is also the same as that observed in s. typhimurium. | 1975 | 238937 |
| mutations affecting glutamine synthetase activity in salmonella typhimurium. | a positive selection procedure has been devised for isolating mutant strains of salmonella typhimurium with altered glutamine synthetase activity. mutants are derived from a histidine auxotroph by selecting for ability to grow on d-histidine as the sole histidine source. we hypothesize that the phenotype may be based on a regulatory increase in the activities of the d-histidine racemizing enzymes, but this has not been established. spontaneous glutamine-requiring mutants isolated by the above se ... | 1975 | 238935 |
| deoxyribose-5-phosphate aldolase from salmonella typhimurium. | 1975 | 237187 | |
| purine nucleoside phosphorylase from escherichia coli and salmonella typhimurium. purification and some properties. | the purine nucleoside phosphorylases from escherichia coli and from salmonella typhimurium have been purified to electrophoretic homogeneity and crystallized. comparative studies revealed that the two enzymes are very much alike. they obey simple michaelis-menten kinetics for their substrates with the exception of phosphate for which they show negative cooperativity. gel filtration on sephadex g-200 of the native enzymes revealed a molecular weight for both enzymes of 138000 plus or minus 10%. b ... | 1975 | 235429 |
| differential fluorescence labelling with 5-dimethyl-aminonaphthalene-1-sulfonyl chloride of intact cells and isolated membranes in salmonella typhimurium and acholeplasma laidlawii. | for fluorescence labelling intact cells and isolated cell envelopes (membranes) from salmonella typhimurium and acholeplasma laidlawii were treated with mixed dansylchloride-lecithin-cholesterol vesicles. this kind of dansylation, which has been supposed to be specific for cell surface proteins, produced fluorescent protein pattern after sds-polyacrylamide gel electrophoresis only when isolated envelopes were dansylated. acid hydrolysis of fluorescent cell envelopes of salmonella typhimurium yie ... | 1975 | 235245 |
| microsomal activation to mutagens of antischistosomal methyl thioxanthenones and initial tests on a possibly non-mutagenic analogue. | five methylthioxanthenone and methylbenzothiopyranoindazole analogues, including lucanthone (miracil d), are non-mutagenic for salmonella typhimurium but are activated to mutagens by a rat liver microsome preparation. hydroxymethyl analogues, including hycathone (etrenol), are mutagenic in the absence of microsomes. it seems reasonable to assume that the hydroxymethyl derivatives are the more proximal mutagens and that salmonella is unable to carry out the hydroxylation necessary for mutagen act ... | 1975 | 235087 |
| deoxycytidine triphosphate deaminase of salmonella typhimurium. purification and characterization. | deoxycytidine triphosphate deaminase (ec 3.5.4., dctp aminohydrolase) of salmonella typhimurium lt2 has been pruified 500-fold. the reaction requires the presence of mg-2plus, mn-2plus, ca-2lus, or co-2plus. kinetics of the reaction with varying mg-2plus concentrations, keeping the concentration of dctp constant, suggests that the true substrate of the reaction is mgdctp. the dependence of the rate of reaction on dctp concentration in the presnece of 5-fold excess of mg-2plus is sigmoid, with a ... | 1975 | 234434 |