| [effect of mutations for adenylate cyclase (cya) and the cyclic adenosine monophosphate receptor protein (cgp) on the gene expression of nucleoside catabolism in escherichia coli]. | the effect of cya and crp mutations on the expression of the activity of nucleoside catabolizing genes has been studied in escherichia coli. it is found that cya and crp mutants lose their ability to grow on nucleosides as carbon sources in spite of the preservation of the basal levels of nucleoside catabolizing enzymes, found in cell-free extracts of cya and crp mutants. it is shown that cya and crp mutations completely release the influence of the regulatory gene cytr on the activity of uridin ... | 1978 | 203511 |
| rotavirus as a cause of diarrhea in pigs. | a rotavirus (reovirus-like agent) was associated with diarrheal diseases occurring in 1- to 4-week-old suckling pigs in 8 herds and in weaned pigs in 2 herds. transmissible gastroenteritis virus was also detected in 2 of these herds, as was enteropathogenic escherichia coli in 5 herds. morbidity was generally greater than 80% in pigs of the affected age group within these herds, and mortality from diarrhea ranged from 7 to 20%. the disease due to rotavirus in suckling pigs appeared similar to th ... | 1978 | 203565 |
| cyclic amp regulation of the hexose phosphate transport system in escherichia coli. | synthesis of the hexosephosphate transport system in escherichia coli required the cyclic amp-receptor protein regulatory complex. the apparent km value for hexosephosphate activity was affected by the level of phosphate in the uptake environment. | 1978 | 203569 |
| sequence of b cytochromes relative to ubiquinone in the electron transport chain of escherichia coli. | a ubiquinone-deficient mutant, carrying mutations in two genes affecting ubiquinone biosynthesis, has been used, in comparison with a normal strain, to determine the sequence of some of the components of the electron transport chain of escherichia coli. the amounts of cytochromes reduced during aerobic steady-state conditions were estimated by comparing low-temperature difference spectra of normal or ubiquinone-deficient membranes with either d-lactate or reduced nicotinamide adenine dinucleotid ... | 1978 | 203570 |
| mapping and characterization of the nad genes in salmonella typhimurium lt-2. | an ampicillin enrichment technique was used to isolate 39 nicotinic acid-requiring mutants of salmonella typhimurium lt-2. using interrupted-mating and transductional mapping procedures, three loci, designated nada, nadb, and nadc, were identified. these loci mapped at 33, 82, and 6 min, respectively, on the s. typhimurium linkage map. the arrangement of the loci on the salmonella linkage map corresponded closely to the nada, nadb, and nadc loci on the escherichia coli k-12 linkage map, indicati ... | 1978 | 203571 |
| cytoplasmic membrane vesicles of escherichia coli. ii. orientation of the vesicles studied by localization of enzymes. | | 1978 | 203572 |
| polyoma virus complementary rna directs the in vitro synthesis of capsid proteins vp1 and vp2. | polyoma virus complementary rna, synthesized in vitro by using highly purified escherichia coli rna polymerase and nondefective form i polyoma dna, was translated in a wheat germ cell-free system. polypeptides were synthesized that comigrated on sodium dodecyl sulfate-polyacrylamide gels with the polyoma capsid proteins vp1 and vp2, although most of the cell-free products were of smaller molecular weights. the vp1-size protein specifically immunoprecipitated with anti-polyoma virus serum, and up ... | 1978 | 203720 |
| thermolabile repression of cephalosporinase synthesis in citrobacter freundii. | an unusual regulatory system of cephalosporinase synthesis in citrobacter freundii has been found. when the bacteria are grown at 20 c, the cephalosporinase is synthesized as a typical inducible enzyme and benzylpenicillin acts as an effective inducer. the enzyme, however, is synthesized in the absence of the inducer at growth temperatures above 25 c. when the growth temperature is shifted from 20 c to 37 c, the induction of enzyme synthesis is observed after about one half of the organism doubl ... | 1977 | 203825 |
| role of cyclic gmp in the action of heat-stable enterotoxin of escherichia coli. | | 1978 | 203862 |
| spin labeling of a cysteine residue of the escherichia coli outer membrane lipoprotein in its membrane environment. | a method was developed to attach a spin label to a specific site on the structural lipoprotein of the escherichia coli outer membrane in situ. this method takes advantage of the fact that the outer membrane of wild-type e. coli contains few residues reactive towards sulfhydryl reagents. a mutant e. coli strain has been isolated [suzuki, h., nishimura, y., iketani, h., campisi, j., hirashima, a., inouye, m. & hirota, y. (1976) j. bacteriol. 127, 1494-1501] in which the second position from the ca ... | 1978 | 203927 |
| uracil incorporation: a source of pulse-labeled dna fragments in the replication of the escherichia coli chromosome. | uracil is incorporated into newly synthesized dna by mutants of escherichia coli with reduced levels of dutpase (dutp nucleotidohydrolase; ec 3.6.1.23). excision-repair of the incorporated uracil results in the generation of labeled dna fragments that appear after brief pulses with [(3)h]thymidine [tye, b-k., nyman, p.-d., lehman, i. r., hochhauser, s. & weiss, b. (1977) proc. natl. acad. sci. usa 74, 154-157]. uracil is also incorporated into the newly synthesized dna of strains of e. coli that ... | 1978 | 203931 |
| dna intermediates at the escherichia coli replication fork: effect of dutp. | we have directly tested the hypothesis that elevated levels of dutp cause the formation of small dna fragments at the replication fork of escherichia coli. addition of increasing levels of dutp to lysates on cellophane discs results in an increasing number of strand scissions in the newly replicated dna. lysates of strains defective in dutpase produce many more scissions at the same level of dutp. the size distribution of okazaki pieces obtained in vivo can be reconstituted in vitro on cellophan ... | 1978 | 203932 |
| two-component ribonucleotidyl transferase from escherichia coli. iii. effect of nucleoside diphosphates on synthesis and pyrophosphorolysis of polyribonucleotides by the enzyme. | 1. the capacity of two-component ribonucleotidyl transferase to catalyze pyrophosphorolysis of polyribonucleotides is studied. 2. it is shown that nucleoside diphosphates (ndp), not being substrates for the enzyme, activate both the synthesis and pyrophosphorolysis of polynucleotides by the enzyme. the concentration of ndp is important for this effect: with an increase of ndp concentration the rate of synthesis increases and reaches a plateau at 10(-5) m ndp, while the rate of pyrophosphorolysis ... | 1978 | 204351 |
| the purification and characterization of a dna nicking-closing enzyme from bacillus megaterium. | although several eucaryote dna nicking--closing (n--c) enzymes have been characterized, only the escherichia coli enzyme has been extensively studied amongst procaryotes. the latter enzyme is distinctly different from the eucaryotic enzymes and we have therefore purified the n--c enzyme from bacillus megaterium to determine if procaryotes form a distinctive class of n--c enzymes. the purified b. megaterium n--c enzyme has a molecular weight of 120,000, only partly relaxes negative supercoils, do ... | 1978 | 204401 |
| dna-directed in vitro synthesis of escherichia coli beta-isopropylmalate dehydrogenase. | the in vitro synthesis of beta-isopropylmalate dehydrogenase (ec 1.1.1.85), an enzyme involved in leucine biosynthesis, has been obtained using as template dna from the hybrid plasmid (plc1) which contains the escherichia coli leucine operon. enzyme synthesis in vitro is stimulated about 2-fold by guanosine-5'-diphosphate-3'-diphosphate and inhibited about 60% by 2 x 10(-4) m l-leucine. | 1978 | 204639 |
| aspartokinase i-homoserine dehydrogenase i of escherichia coli k12. concentration-dependent dissociation to dimers in the presence of l-threonine. | the concentration-dependent association-dissociation equilibrium of the bifunctional enzyme aspartokinase i-homoserine dehydrogenase i of escherichia coli k12 has been investigated at ph 7.6 in the presence of 10 mm l-threonine and 0.1 m kcl by equilibrium gel permeation monitored by a single-photon counting spectrophotometer. the results obtained are consistent with the existence of a dimer-tetramer equilibrium with the association constant of 2.6 x 10(7) m-1 (deltag0 = -9.9 kcal/mol of dimer). ... | 1978 | 204643 |
| mitogen induction of murine c-type viruses. iv. effects of lipoprotein e. coli, pokeweed mitogen and dextran sulphate. | lipoprotein e. coli, a b-cell mitogen, is identified as a new agent inducing the release of endogenous c-type virus from mouse spleen cells. like lipopolysaccharide, a previously identified inducer, this compound has a synergistic effect with 5-bromo-2'-deoxyuridine. induced virus has the characteristic density as well as morphology of c-type viruses. budding viruses are detected on cultured balb/c cells by electron microscopy 2 to 4 days following culturing in the presence of lipoprotein. pokew ... | 1978 | 204733 |
| oxygen toxicity: comparative sensitivities of membrane transport, bioenergetics and synthesis in escherichia coli. | the oxygen sensitivities of basic cell functions were compared to evaluate their significance as potential causes of the reversible growth inhibition produced in escherichia coli by exposure to hyperbaric oxygen. growth and net incorporation of radioactive glucose into cell structure, and specifically in to protein, were completely inhibited in approximately 1/20 of a generation by a gas phase containing 4.2 atmospheres of oxygen. the inhibition occured before there was significant decrement in ... | 1977 | 204854 |
| pores in the outer membrane of escherichia coli k12: involvement of proteins b and e in the functioning of pores for nucleotides. | | 1978 | 204859 |
| regulation of cessation of respiration and killing by cyclic 3',5'-adenosine monophosphate and its receptor protein after far-ultraviolet irradiation of escherichia coli. | | 1978 | 204860 |
| regulation of the deo operon in escherichia coli: the double negative control of the deo operon by the cytr and deor repressors in a dna directed in vitro system. | the synthesis of the four enzymes of the deo operon in escherichia coli is known from in vivo experiments to be subject to a double negative control, exerted by the products of the cytr and deor genes. a dna-directed in vitro protein synthesizing system makes the deo enzymes (exemplified by thymidine phosphorylase) in agreement with in vivo results. enzyme synthesis is stimulated by cyclic amp and repressed by the cytr and deor gene products. repression by the cytr repressor is reversed by cytid ... | 1978 | 204861 |
| an rna transcribed from dna at the origin of phage fd single strand to replicative form conversion. | phage fd dna complexed with dna binding protein i was used by escherichia coli rna polymerase (nucleoside triphosphate:rna nucleotidyltransferase, ec 2.7.7.6) to synthesize an rna at the origin of single strand to double strand replication. the isolated ori-rna gave a simple fingerprint after nucleolytic digestion and has a length of about 30 nucleotides. the characterization of the oligonucleotides from the nuclease digest and the extension of the ori-rna with dna polymerase i and subsequent re ... | 1978 | 204927 |
| nucleotide sequence of the simian virus 40 hind-k restriction fragment. | the restriction fragment hind-k represents 4.2% of the genome of simian virus 40 (sv40) and is located near the middle of the late region. its nucleotide sequence is reported here. it was mainly established by analysis of transcription products, synthesized by means of escherichia coli rna polymerase and nucleoside triphosphates, one of which was (alpha-32p)-labeled. strand assignment was possible by hybridization of asymmetric, labeled transcripts of total sv40 dna to filter-bound hind-k fragme ... | 1978 | 205417 |
| electron-spin-resonance studies of the lipoamide 'swinging arm' of the pyruvate dehydrogenase multienzyme complex of escherichia coli [proceedings]. | | 1978 | 205464 |
| transcription of bk virus dna by escherichia coli rna polymerase: size and sequence analysis of rna. | transcription of human papovarirus bk superhelical dna by escherichia coli rna polymerase yielded symmetric rna with an average chain length of 1,3000 nucleotides. all regions of human papovavirus bk dna were equally transcribed. at least four initiation sites were available to the procaryotic enzyme. | 1978 | 205683 |
| expression of a bacterial gene turned on by a potent carcinogen. | contrary to mutagenesis, lysogenic induction produced by chemical carcinogens occurs in the majority of a population of lysogenic cells. such a mass effect can therefore be measured at the biochemical level using an e. coli tester strain in which the galactose operon has been put under the negative control of the lambda repressor. in this publication we show that galactokinase synthesis is turned on by aflatoxin b1 metabolites within an hour after treatment of the tester bacteria. such a biochem ... | 1978 | 205783 |
| polynucleotide kinase from a t4 mutant which lacks the 3' phosphatase activity. | polynucleotide kinase from e. coli infected with the pset 1 mutant of bacteriophage t4 has been isolated. the pset 1 enzyme purifies similarly to normal polynucleotide kinase and effectively transfers the gamma phosphate of atp to the 5' terminal hydroxyl of dna and rna. the pset 1 and normal enzymes require similar magnesium ion concentrations, have the same ph optima and are both inhibited by inorganic phosphate. however, the pset 1 enzyme is totally lacking the 3' phosphatase activity associa ... | 1978 | 205838 |
| properies of trnaphe from yeast carrying a spin label on the 3'-terminal. interaction with yeast phenylalanyl-trna synthetase and elongation factor tu from escherichia coli. | the 2-thioketo function of trnaphe-c-s2c-a in which the penultimate cytidine residue is replaced by 20thiocytidine can serve as a site of specific attachment of spin label. by alkylation of trnaphe-c-s2c-a with iodoacetamide or its spin label derivatives trnaphe-c-(acm)s2c-a or trnaphec-(sl)s2c-a are formed. the enzymatic phenylalanylation of these trnasphe revealed that the 2-position of the penultimate cytidine can be modified without impairing this enzymatic reaction but there exists a steric ... | 1978 | 205839 |
| growth of escherichia coli on glucosamine 6-phosphate: selection of a constitutive hexose phosphate transport system mutant. | glucosamine 6-phosphate was found to be a substrate but not an inducer for the hexose phosphate transport system of escherichia coli. wild-type cells grow very poorly on glucosamine 6-phosphate. a mutant was selected that will grow rapidly on glucosamine 6-phosphate because it contains a constitutive hexose phosphate transport system. | 1978 | 206329 |
| two kinds of mutants defective in multiple carbohydrate utilization isolated from in vitro fosfomycin-resistant strains of escherichia coli k--12. | two types of in vitro fosfomycin-resistant mutants defective in multiple carbohydrate utilization were selected from escherichia coli strain k--12. one mutant, fr182, was defective in phosphoenolpyruvate: sugar phosphotransferase system and the ability to form adenosine 3',5'-cyclic monophosphate (camp) was lowered. another mutant, fr190, was defective in camp formation. restoration by camp of fosfomycin (fom) sensitivity coupled with recovery of utilization of many carbohydrates including sn-gl ... | 1978 | 206529 |
| structure-function relationships in the arginine pathway carbamoylphosphate synthase of saccharomyces cerevisiae. | the arginine pathway carbamoylphosphate synthase (cpsase a) from saccharomyces cerevisiae was shown to be highly unstable and could not be substantially purified. in spite of this instability, a number of important properties of this enzyme were determined with crude preparations. a molecular weight of 140,000 (7.9s) was estimated for the native enzyme by sucrose gradient centrifugation; a significantly higher value, 175,000, was obtained by gel filtration on sephadex. the enzyme is an aggregate ... | 1978 | 206535 |
| superoxide dismutase and oxygen metabolism in streptococcus faecalis and comparisons with other organisms. | streptococcus faecalis contains a single superoxide dismutase that has been purified to homogeneity with a 55% yield. this enzyme has a molecular weight of 45,000 and is composed of two subunits of equal size. it contains 1.3 atoms of manganese per molecule. its amino acid composition was determined and is compared with that for the superoxide dismutases from escherichia coli, streptococcus mutans, and mycobacterium lepraemurium. when used as an antigen in rabbits, the s. faecalis enzyme elicite ... | 1978 | 206536 |
| the deoxyribonuclease induced after infection of kb cells by herpes simplex virus type 1 or type 2. i. purification and characterization of the enzyme. | the deoxyribonuclease induced in kb cells by herpes simplex virus (hsv) type 1 and type 2 has been purified. both enzymes are able to completely degrade single- and double-stranded dna yielding 5'-monophosphonucleotides as the sole products. a divalent cation, either mg2+ or mn2+, is an absolute requirement for catalysis and a reducing agent is necessary for enzyme stability. the maximum rate of reaction is achieved with 5 mm mgcl2 for both hsv-1 and hsv-2 dnase. the optimum concentration for mn ... | 1978 | 206546 |
| neutral lipid accumulation in the membranes of escherichia coli mutants lacking diglyceride kinase. | we have developed a rapid autoradiographic screening assay for detecting diglyceride kinase in colonies of escherichia coli and have isolated four strains lacking this enzyme. the gene (designated dgk) which is altered in these mutants is cotransduceable with the malb locus, near minute 90 on the chromosome. the membranes of strain rz60 (which carries the dgk-6 lesion) contain substantial amounts of 1,2-diglyceride, representing approximately 8% of the total lipid. in contrast, wild type cells o ... | 1978 | 206553 |
| the dnab gene product of escherichia coli. i. purification, homogeneity, and physical properties. | the dnab gene product was purified to homogeneity and its physical properties were characterized. purification was aided by the use of the escherichia coli strain. mv12/28, which overproduced the dnab gene product 10-fold (wickner, s. h., wickner, r. b., and raetz, c. r. h. (1976) biochem. biophys. res. commun. 70, 389-396) and by taking advantage of the enzyme's high affinity for both deae-cellulose and phosphocellulose. the most highly purified fractions gave a single stained band on native, p ... | 1978 | 206559 |
| the dnab gene product of escherichia coli. ii. single stranded dna-dependent ribonucleoside triphosphatase activity. | the single-stranded dna-dependent ribonucleoside triphosphatase activity of the escherichia coli dnab gene product was characterized. purine ribonucleoside triphosphates were the preferred substrates, but all ribonucleoside triphosphates were cleaved at the gamma position to yield ribonucleoside diphosphates and pi. the enzyme required mg2+, which could be replaced by mn2+ but with lower activity. the ph optimum was 7.5 in either tris-hcl or phosphate buffer. the km for mgatp was 0.59 mm and the ... | 1978 | 206560 |
| the chromosomal location and pleiotropic effects of mutations of the nira+ gene of escherichia coli k12: the essential role of nira+ in nitrite reduction and in other anaerobic redox reactions. | cytochrome c552, which has been implicated as an electron carrier for nitrite reduction by escherichia coli, has been separated from nadh-nitrite oxidoreductase activity. the cytochrome is therefore not required for the reduction of nitrite by nadh in vitro. nevertheless, some mutants which were selected by their inability to use nitrite as a nitrogen source during anaerobic growth synthesize neither nadh-nitrite oxidoreductase nor cytochrome c552. the defects in these mutants are due to mutatio ... | 1978 | 206651 |
| [effect of histones on a change in the enzymatic activity of escherichia coli and staphylococcus aureus cells]. | histones have been found to interfere with the permeability of the cellular membranes of escherichia coli and staphylococcus aureus, this resulting in the liberation of 14c-amino acids, the uv-absorbing endogenous material, and the products of rna degradation. histones, particularly arginine-rich fractions, stimulated the rnaase activity of the bacteria. histones inhibited the phosphatase activity of e. coli and stimulated that of staphylococcus aureus. the atpase activity of the cells increased ... | 1978 | 206806 |
| [changes in the electron transport chain in escherichia coli depending on the cultivation conditions and growth phase]. | changes in the electron transport chain of e. coli k-12 were studied as a function of the growth phase and the nature of a terminal electron acceptor in the growth medium. the content of flavins in the preparations of bacterial membranes hardly changed in all cases. the highest concentration of quinones was observed in the bacterial membranes at the stationary growth phase under anaerobic conditions of growth in the presence of nitrate. these membranes contained also the greatest amount of cytoc ... | 1978 | 206807 |
| [fatty acid makeup of escherichia coli cells with repressed and derepressed phosphohydrolase biosynthesis]. | fatty acid composition of the cells of escherchia coli wild strains k-10, and k-12 and the mutants of the regulatory genes for alkaline phosphatase was studied in conditions of repression and derepression of biosynthesis of phosphohydrolases. derepression of phosphohydrolases was not accompanied with specific changes in fatty acid composition of the cells. an increase in the content of cyclopropanic acid in conditions of phosphorus deficiency and a decrease in the level of unsaturated fatty acid ... | 1978 | 206808 |
| evidence for splicing of avian sarcoma virus 5'-terminal genomic sequences into viral-specific rna in infected cells. | the 5'-terminal nucleotide sequences of the avian sarcoma virus (asv) genome are transcribed by the reverse transcriptase in vitro into a dna transcript that represents the entire distance ( approximately 100 nucleotides) between the trna(trp) primer molecule and the 5' terminus. we have used these dna(100) transcripts in hybridization reactions with asv-specific rna from infected avian cells and find nucleotide sequences complementary to these transcripts on all of the various size classes of v ... | 1978 | 206893 |
| electrophoretic isoenzyme patterns of entamoeba histolytica and entamoeba coli. | cultures of 14 stocks of entamoeba histolytica and one only of entamoeba coli were compared by electrophoretic patterns of three enzymes: glucose-phosphate isomerase, phosphoglucomutase and l-malate: nadp+ oxidoreductase (oxaloacetate-decarboxylating). easily distinguished patterns divided e. histolytica into three groups, whilst a distinctly different pattern for e. coli was also seen. | 1978 | 206991 |
| identification of mitochondrial gene products by dna-directed protein synthesis in vitro. | 1. a cell-free system, derived from escherichia coli is highly active in the linked transcription-translation of yeast mtdna from both wild-type and petite strains. 2. the products of synthesis are short (mr less than 10 000) hydrophobic polypeptides, which show a high tendency to aggregate in a specific fashion with e. coli and mitochondrial proteins. aggregation is extremely persistent: alkali, sodium dodecyl sulphate/urea, guanidinium . hcl and carboxymethylation reduce it, but do not elimina ... | 1978 | 207328 |
| the dependence of escherichia coli asparaginase ii formation on cyclic amp and cyclic amp receptor protein. | the amount of asparaginase ii in an escherichia coli wild-type strain (cya+, crp+) markedly increased upon a shift from aerobic to anaerobic growth. however, no such increase occurred in a mutant (cya) lacking cyclic amp synthesis unless supplemented with exogenous cyclic amp. since a mutant (crp) deficient in cyclic amp receptor protein also did not support the anaerobic formation of this enzyme, it is concluded that the formation of e. coli asparaginase ii depends on both cyclic amp and cyclic ... | 1978 | 207402 |
| formation of okazaki fragments in polyoma dna synthesis caused by misincorporation of uracil. | when dutp replaced dttp during polyoma dna replication in isolated cell nuclei, radioactivity from labeled deoxynucleoside triphosphates was almost exclusively recovered in very short okazaki fragments and incorporation ceased after a short time. addition of uracil, a known inhibitor of the enzyme uracil-dna glycosidase (lindahl et al., 1977), increased total synthesis and shifted the incorporation to longer progeny strands. the presence of as little as 2.5% of dutp in a dttp-containing system g ... | 1978 | 207436 |
| streptomycin uptake via an inducible polyamine transport system in escherichia coli. | | 1978 | 207523 |
| acquisition of ability to utilize xylitol: disadvantages of a constitutive catabolic pathway in escherichia coli. | ribitol+ strains of escherichia coli acquire the ability to utilize xylitol by mutating to constitutive production of the coordinately controlled ribitol catabolic enzymes ribitol dehydrogenase (rdh) and d-ribulokinase (drk). such strains concomitantly acquire toxicity to galacitol and l-arabitol, and to d-arabitol if they are unable to utilize it for growth. strains selected for resistance to these polyols have drk structural gene mutations or other mutations that eliminate the constitutive pro ... | 1978 | 207668 |
| enzymes of purine metabolism in mycoplasma mycoides subsp. mycoides. | the major pathways of ribonucleotide biosynthesis in mycoplasma mycoides subsp. mycoides were proposed previously from studies of its usage of radioactive purines and pyrimidines. to interpret more fully the pattern of purine usage, we have assayed cell-free extracts of this organism for several enzymes associated with the salvage synthesis of purine nucleotides. m. mycoides possessed phosphoribosyltransferases for adenine, guanine, and hypoxanthine, purine nucleoside phosphorylase, gmp reductas ... | 1978 | 207675 |
| acetate kinase production by escherichia coli during steady-state and transient growth in continuous culture. | the synthesis of acetate kinase by escherichia coli atcc 9637 was studied during growth in anaerobic continuous cultures under steady-state and transient conditions. during growth in anaerobic, glucose-limited chemostats, acetate kinase synthesis was linearly associated with growth. two types of non-steady-state transients were studied: the perturbation in one was the addition of glucose alone, and, in the second, glucose plus casamino acids. during the nutritional shift-up in the second case, b ... | 1978 | 207678 |
| transient repression of beta-galactosidase synthesis by glucose-6-phosphate in a mutant of escherichia coli lacking enzyme ii specific for glucose in the phosphoenolpyruvate-sugar phosphotransferase system. | the effects of glucose and glucose-6-phosphate in initiating the repression of beta-galactosidase synthesis were studied using a mutant of escherichia coli k12 which lacks glucose-specific enzyme ii of the phosphoenolpyruvate-sugar phosphotransferase system. it was found that glucose-6-phosphate causes transient repression of beta-galactosidase synthesis but glucose does not cause transient repression in this mutant. evidence was obtained that both the presence of an active transport system for ... | 1978 | 207684 |
| restriction enzyme sites on the avian rna tumor virus genome. | full-size single-stranded dna transcripts of the avian rna tumor virus genome were isolated from the products of the endogenous reaction of detergent-disrupted avian sarcoma virus particles. these transcripts were converted with escherichia coli dna polymerase i and 32p-labeled nucleoside triphosphates into labeled double-stranded dna. the latter dna was used to map the sites of action of seven restriction enzymes (pvu i, hpa i, kpn i, xba i, ecori, hindiii, and xho i) on the genome of three str ... | 1978 | 207898 |
| rna:dna hybrids are more stable than dna:dna duplexes in concentrated perchlorate and trichloroacetate solutions. | rates of formation of rna:dna hybrids have been measured as a function of temperature and compared to dna:rna duplex denaturation temperatures in 4 m sodium perchlorate, 4 m naclo4-6 m urea, and 3 m rubidium trichloracetate solvents. the usual bell shaped curves of reaction rate versus temperature were observed. the optimal temperatures for the rna:dna association reaction are 5 degrees to 12 degrees greater than the tm's for dna:dna denaturation in these solvents, just as in formamide. r-loops ... | 1978 | 208059 |
| pathological changes in the small intestine of neonatal calves naturally infected with reo-like virus (rotavirus). | nine calves, of which six had been challenged with an enteropathogenic strain of escherichia coli, were found to be naturally infected with rotavirus. rotavirus was recovered from the faeces of six calves and rotavirus antigen was detected in the intestinal mucosa of all calves. stunting and fusion of villi were seen principally in the proximal and middle small intestine, where rotavirus antigen was detected by immunofluorescence. typical lesions of enteric colibacillosis were found in the dista ... | 1978 | 208222 |
| the activity of salmonella phage p22 gene 24 product in escherichia coli. | | 1978 | 208254 |
| the biology and pathology of oxygen radicals. | superoxide radicals (o2-) are commonplace products of the biological reduction of oxygen. their intrinsic reactivity and ability to generate other more reactive entities constitute a threat to cellular integrity. superoxide dismutases, enzymes that catalytically scavenge these radicals, have evolved to meet this threat. these metalloenzymes are essential for respiring organisms to survive. several compounds, such as the antibiotic streptonigrin and the herbicide paraquat, augment the production ... | 1978 | 208444 |
| an intramolecularly quenched fluorescent tripeptide as a fluorogenic substrate of angiotensin-i-converting enzyme and of bacterial dipeptidyl carboxypeptidase. | the n-acyltripeptide 2-aminobenzoylglycyl-p-nitrophenylalanylproline was synthesized and applied as a substrate in the assay of angiotensin-i-converting enzyme from calf lung and human serum, and of the bacterial dipeptidyl carboxypeptidase from escherichia coli. this compound belongs to a new class of substrates for proteolytic enzymes, having the general structure f--x--q in which fluorescence of group f is quenched by intramolecular interaction with the group q. enzymatic cleavage of the pep ... | 1978 | 208842 |
| properties of an escherichia coli cytotoxin. | isoelectric focusing of a heat-labile cytotoxin of escherichia coli h30 revealed the presence of two molecular variants, pi 7.2 and a comparatively small quantity of pi 6.8. predominant component pi 7.2 had a molecular weight of 28,000, induced some fluid accumulation in rabbit ileal loops, and showed no morphological response in y-1 cells but a strong cytotoxic effect on vero cells. | 1978 | 208977 |
| cell-free synthesis of proteins related to sn-glycerol-3-phosphate transport in escherichia coli. | an escherichia coli periplasmic protein (glpt) related to sn-glycerol-3-phosphate transport was synthesized in a cell-free system directed by hybrid plasmic cole1-glpt dna. the in vitro product cross-reacted with antisera against the purified protein. the cole1-glpt dna-directed cell-free system was induced by sn-glycerol-3-phosphate and phosphonomycin and was dependent on cyclic amp. the in vitro-synthesized protein showed the characteristics of a multimeric protein, as did the purified peripla ... | 1978 | 209011 |
| activation of adenylate cyclase by heat-labile escherichia coli enterotoxin. evidence for adp-ribosyltransferase activity similar to that of choleragen. | highly purified, polymyxin-released, low molecular weight escherichia coli heat-labile enterotoxin (lt) catalyzed the hydrolysis of nad to adp-ribose and nicotinamide. this nad glycohydrolase activity was stimulated by dithiothreitol and was independent of cellular components. nicotinamide formation was enhanced by arginine methyl ester > d-arginine congruent with l-arginine congruent with guanidine. a 20-fold increase in activity was noted with arginine methyl ester, and maximal activity again ... | 1978 | 209060 |
| nucleoside 5'-monophosphate analogues. synthesis of 5'-sulfamino-5'-deoxynucleosides. | the synthesis of two new nucleotide analogues is described. 5'-sulfamino-5'-deoxyadenosine (1) was prepared by reaction of 5'-amino-5'-deoxyadenosine with (ch3)3n.203, and 5'-sulfamino-5'-deoxythymidine (2) was prepared from 5'-amino-5'-deoxythymidine by a similar reaction. the 5'-sulfamino nucleosides are shown to be quite stable to hydrolysis in acidic or basic aqueous solution tests show that these compounds do not inhibit the growth of escherichia coli or l1210 cells at concentrations less t ... | 1978 | 209190 |
| genome organization of rna tumor viruses. i. in vitro synthesis of full-genome-length single-stranded and double-stranded viral dna transcripts. | genome-length complementary dna (cdna) transcripts were synthesized in vitro by using purified virions of avian myeloblastosis virus. moloney murine leukemia virus, and clone 124 mouse sarcoma virus. the size of the genomelenth cdna transcripts was measured on either alkaline sucrose gradients or alkaline agarose gels. the longest cdna transcripts synthesized by using avian myeloblastosis virus, moloney murine leukemia virus, and clone 124 mouse sarcoma virus were 7, 9 and 6 kilobases (kb), resp ... | 1978 | 209213 |
| oral hydration rotavirus diarrhoea: a double blind comparison of sucrose with glucose electrolyte solution. | of 57 male children, aged 5 months to 2 1/2 years with rotavirus diarrhoea, 28 were given oral therapy with sucrose electrolyte solution and 29 were given glucose electrolyte solution in a randomised double-blind trial. all were rehydrated and remained so on oral therapy alone. these patients were compared with 44 children, also with rotavirus, who were treated only with intravenous hydration. the oral therapy and intravenous therapy groups did not differ clinically in the rate of rehydration or ... | 1978 | 209263 |
| viomycin favours the formation of 70s ribosome couples. | the peptide antibiotic viomycin at a concentration of 10 mum inhibits e. coli ribosomes to the extent of about 70% as measured in the poly (u) system, and to about 85% in a natural mrna (r17) system. ribosomes from m. smegmatis show no activity at all at this concentration of the antibiotic. experiments on the mg+2 dependent dissociation and association of the ribosomal subunits revealed that viomycin stabilizes the 70s couples and promotes association of ribosomal subunits. this response is rel ... | 1978 | 209306 |
| catabolite repression in escherichia coli mutants lacking cyclic amp. | the regulation of catabolite repression of beta-galactosidase has been studied in escherichia coli mutants deleted for the adenyl cyclase gene (cya delta), and thus unable to synthesize cyclic amp. it has been found that, provided a second mutation occurs either in the crp gene coding for the catabolite gene activator protein (cap) or in the lactose region, these mutants exhibit catabolite repression. if the catabolite repression seen in the mutant strains corresponds to the mechanism operating ... | 1978 | 209309 |
| molecular dosimetry of the chemical mutagen ethyl methanesulfonate in escherichia coli and in v-79 chinese hamster cells. | | 1978 | 209321 |
| escherichia coli resistance to beta-lactam antibiotics through a decrease in the affinity of a target for lethality. | | 1978 | 209344 |
| transduction of a bacterial gene into mammalian cells. | the transduction of an escherichia coli gene into mammalian cells is described. a supressor trna gene was linked to a simian virus 40 (sv40) vector in vitro and the recombinant was used to transfect rat embryo cells and monkey kidney cells. the hybrid sv40 genome, sv40-su+ iii, retained genetic information required for autonomous replication and cellular transformation and had a 1300-base-pair dna segment in the late gene region (between the restriction endonuclease sits hpa ii at 0.735 and ecor ... | 1978 | 209451 |
| recognition site of escherichia coli b restriction enzyme on phi xsb1 and simian virus 40 dnas: an interrupted sequence. | methyl groups placed on varphixsb1 replicative form dna by the escherichia coli b modification enzyme are located in the overlap between fragments mbo ii-3 and alu i-2, a 61-base-pair dna segment. mutations that led to loss of susceptibility to restriction by e. coli b occurred within this segment at three positions spanning 14 nucleotides. a sequence difference between varphixsb1 and varphixam3cs70, a varphix174 strain not restricted by e. coli b, occurs at one of these positions. the site on s ... | 1978 | 209460 |
| new and old agents in diarrhea: a prospective study of an indigenous adult african population. | we conducted a prospective study 77 indigenous african adults with acute diarrhea seeking care at the major hospital in nairobi, kenya, to determine the major pathogens responsible for this syndrome in adults. fecal and blood specimens were collected and examined for enteric bacterial pathogens, viruses, and parasites. in 13 (26%) inpatients and 11 (49%) outpatients shigella was found, and heat-labile and heat-stable forms of enterotoxigenic escherichia coli were found in 9 (18%) inpatients and ... | 1978 | 209697 |
| proteins that affect dna conformation. | in eucaryotic cells virtually all of the dna is complex with proteins to form a unit fiber approximately 100 a in diameter. chromatin is formed by the higher order coiling of the unit fiber. in procaryotic cells, as exemplified by e. coli, the actual structure of the chromosome is less clear (218), but the discovery of the dna gyrase raises the possibility that the dna helix in the cell is maintained in an underwound state. it may be important to consider these structural features of dna in futu ... | 1978 | 209728 |
| production and properties of the alpha core derived from the cyclic adenosine monophosphate receptor protein of escherichia coli. | | 1978 | 209817 |
| localization of the hu protein on the escherichia coli nucleoid. | | 1978 | 209942 |
| inhibition of x-ray-induced protection of escherichia coli k-12 cells against the lethal effects of ultra-violet light by nitrofurantoin. | wild-type cells of e. coli k-12 showed increasing u.v. resistance if they were x-irradiated and incubated at 37 degrees c in growth medium before the u.v. exposure. development of higher u.v. resistance could be inhibited by incubating the x-irradiated cells either at temperatures below 15 degrees c, or in the presence of 0.01 m kcn. nitrofurantoin (nf), which was recently found specifically to inhibit inducible enzyme synthesis, had only a transient inhibitory effect on x-ray-induced u.v. resis ... | 1978 | 210134 |
| expression of the histidine operon in rho mutants of escherichia coli. | expression of the escherichia coli histidine operon was measured in four independently isolated sets of strains carrying ten different rho mutations. rho factor does not act as a major regulatory element of histidine operon attenuation. | 1978 | 210156 |
| regulation of the synthesis of catalase and peroxidase in escherichia coli. | | 1978 | 210184 |
| guanosinetriphosphatase activity dependent on elongation factor tu and ribosomal protein l7/l12. | incubation of electrophoretically pure samples of the escherichia coli 50s ribosomal protein l7/l12 together with elongation factor tu leads to the hydrolysis of gtp. addition of elongation factor ts stimulates this reaction. elongation factor g cannot replace elongation factor tu for the ribosome-free gtpase reaction dependent on l7/l12. the data suggest that elongation factor tu and the protein l7/l12 interact directly at the ribosomal a site. | 1978 | 210452 |
| travelers' diarrhea among united states marines in south korea. | a battalion of united states marines traveling to south korea in the spring of 1976 was studied to determine the incidence and etiology of gastroenteritis. during the three weeks they visited south korea, 21% of 694 marines developed diarrhea. stool and serum specimens collected before, during, and after their stay were examined for evidence of infection with salmonella, shigella, and vibrio species, enterotoxigenic and invasive escherichia coli, reovirus-like agent (rvla), and intestinal ova an ... | 1978 | 210660 |
| identification of the transcribing dna strand for the deoxynucleotide kinase gene of bacteriophage t2. | a modified procedure was developed which allows rna--dna hybridization reactions to be performed without the loss in translational capacity of mrna which accompanies hybridization at elevated temperatures or in the presence of the denaturing agent formamide. separated l and r strands of bacteriophage t2 dna were hybridized in the presence of 4 m sodium perchlorate at 37 degrees c with total rna from infected cells. after passage of the hybridization mixture through a nitrocellulose column to rem ... | 1978 | 210792 |
| uridine diphosphate galactose 4-epimerase: nucleotide and 8-anilino-1-naphthalenesulfonate binding properties of the substrate binding site. | escherichia coli udp-galactose 4-epimerase in its native form (epimerase.nad) binds 8-anilino-1-naphthalenesulfonate (ans) at one tight binding site per dimer with a dissociation constant of 25.9 +/- 2.1 micrometer at ph 8.5 and 27 degrees c. this appears to be the substrate binding site, as indicated by the fact that ans is a kinetically competitive reversible inhibitor with a ki of 27.5 micrometer and by the fact that ans competes with ump for binding to the enzyme. upon binding at this site t ... | 1978 | 210796 |
| probes of the structure of phosphoenolpyruvate synthetase: effects of a transition state analogue on enzyme conformation. | phosphoenolpyruvate synthetase of escherichia coli is strongly inhibited by oxalate. the magnitude of the inhibition constant for oxalate suggests that this compound acts to produce a transition state analogue, in keeping with the suggestion of others that oxalate mimics the structure of enolpyruvate, a presumed catalytic intermediate in the enzymatic reaction. the addition of oxalate together with atp results in a dramatic shielding of sensitive amino acid residues from reaction with both n-eth ... | 1978 | 210911 |
| the effect of cholera toxin and heat labile and heat stable escherichia coli enterotoxin on cyclic amp concentrations in small intestinal mucosa of pig and rabbit. | the effect of cholera toxin, heat labile and heat stable escherichia coli enterotoxin on mucosal cyclic amp concentrations was determined on the proximal jejunum of weanling pigs and young rabbits. ligated loops were injected with solutions containing no enterotoxin for control and either cholera toxin, heat labile or heat stable e. coli enterotoxin. the loops were drained after either two, four or six hours incubation at which time accumulated fluid was recorded and mucosal samples removed for ... | 1978 | 210913 |
| effects of antipain (a protease inhibitor) on respiration, viability, and excision of pyrimidine dimers in uv-irradiated escherichia coli cells. | the protease inhibitor antipain increases the effectiveness of uv irradiation on cessation of respiration and cell killing in escherichia coli b/r cultures without affecting excision of pyrimidine dimers. the actions are similar to those caused by cyclic amp in irradiated cultures. | 1978 | 211114 |
| control of biodegradative threonine dehydratase inducibility by cyclic amp in energy-restricted escherichia coli. | to explain the requirement for anaerobic conditions in the induction of biodegradative l-threonine dehydratase in escherichia coli, crookes strain, measurements of cyclic amp (camp) were made during aerobic and anaerobic growth and upon an aerobic-to-anaerobic transition. internal camp levels were similar (5 to 10 mum) throughout exponential growth, whether aerobic or anaerobic, but only during anaerobiosis was threonine dehydratase synthesized. when an exponentially growing aerobic culture was ... | 1978 | 211115 |
| effect of membrane-associated f1 bacteriophage coat protein upon the activity of escherichia coli phosphatidylserine synthetase. | the effects of insertion of the major coat protein of f1 bacteriophage into escherichia coli membranes were investigated under conditions allowing in vivo analysis of phosphatidylserine synthesis. an e. coli strain possessing a temperature-sensitive phosphatidylserine decarboxylase was utilized under conditions in which the decarboxylase activity was reduced but nonlethal. the presence of the coat protein in the host membranes inhibits the activity of the phosphatidylserine synthetase and perhap ... | 1978 | 211116 |
| carbamyl phosphate synthetase of escherichia coli uses the same diastereomer of adenosine-5'-[2-thiotriphosphate] at both atp sites. | carbamyl phosphate synthetase from escherichia coli has been shown to use only the a isomer of adenosine-5'-[2-thiotriphosphate] in both the atpase reaction (mgatp hco3- leads to mgadp + pi) and the carbamyl phosphate synthesis reaction (2mgatp + hco3- + l-glutamine leads to 2mgadp + pi + carbamyl-p + l-glutamate). the b isomer was less than 5% as reactive. in the reverse reaction, only the a isomer of adenosine-5'-[2-thiotriphosphate] is synthesized from adenosine-5'-[2-thiodiphosphate] and car ... | 1978 | 211124 |
| nonspecific effect of m7gmp on protein-rna interactions. | cap analogs m7gmp and m7gdp inhibit binding of eukaryotic initiation factors to reovirus capped mrna but also inhibit complex formation involving uncapped mrna or 18 s rrna. furthermore, escherichia coli dna-dependent rna polymerase binds 18 s rrna and this interaction is also blocked by m7gmp. these results indicate that inhibition by cap analogs is not a stringent test for putative cap-specific binding between proteins and mrna. | 1978 | 211125 |
| a k+ transport atpase in escherichia coli. | a k+ -stimulated atpase in membranes of escherichia coli has been identified as an activity of the kdp system, and atp-driven k+ transport system. three characteristics support association of the atpase with the kdp system: (i) atpase and kdp transport are both repressed by growth in media containing high concentrations of k+; (ii) the atpase and kdp system accept only k+ as substrate, neither requires na+ nor accepts rb+ as a substrate; (iii) the affinity of the atpase and that of th kdp system ... | 1978 | 211128 |
| the tyrosine free radical in ribonucleotide reductase from escherichia coli. | one of the two nonidentical subunits of ribonucleotide reductase from escherichia coli, protein b2, contains an organic free radical required for enzyme activity. earlier isotope subtitution experiments (sjöberg, b.-m., reichard, p. gräslund, a., and ehrenberg, a. (1977) j. biol. chem. 252, 536-541) demonstrated that the radical was localized to a tyrosine residue of the enzyme and suggested that the spin density of the radical was centered at the methylene carbon of tyrosine. however, additiona ... | 1978 | 211133 |
| prospective study of enteropathogens in children with diarrhea in houston and mexico. | during a 22-month period, 595 children with diarrhea and 210 age-matched controls attending clinics in houston (367 children) and mexico (438) were prospectively evaluated for enteric pathogens. enteropathogens associated with disease were shigella (18%), rotavirus (14%), salmonella (9%), toxigenic escherichia coli (6%), and others (12%), including 14 proteus isolates that caused rounding of adrenal cells. enteropathogens were isolated from a greater (p less than 0.001) number of children with d ... | 1978 | 211215 |
| rotavirus (reovirus-like) infection of neonatal ruminants in a zoo nursery. | an outbreak of a pneumoenteric disease occurred in neonates in a zoo nursery. four of seven affected animals died. rotaviruses were observed in the feces of an affected 4-day old impala (aepyceros melampus), a thomson's gazelle (gazella thomsonii) and an addax (addax nasomaculatus). encapsulated escherichia coli also were isolated from the feces. the recovered rotaviruses was antigenically related to bovine rotavirus. a bovine rotavirus vaccine was given orally and no adverse effects were noted. | 1978 | 211273 |
| glutamine-dependent carbamyl-phosphate synthetase (escherichia coli); preparation of subunits. | | 1978 | 211373 |
| gmp synthetase (escherichia coli). | | 1978 | 211374 |
| uridine-cytidine kinase from escherichia coli. | | 1978 | 211379 |
| guanylate kinase from escherichia coli b. | | 1978 | 211389 |
| dihydroorotate dehydrogenase (escherichia coli). | | 1978 | 211391 |
| an electron microscopic method for the mapping of proteins attached to nucleic acids. | an electron microscopic method for demonstrating the presence of and mapping the positions of proteins specifically bound to nucleic acids is described. the nucleic acid-protein complex is treated with dinitrofluorobenzene under conditions such that dinitrophenyl (dnp) groups are attached to nucleophilic groups on the protein, with only a low level of random attachment to the nuclei acid. this product is treated with rabbit anti-dnp igg. the position of the protein-(dnp)n(igg)m complex on the nu ... | 1978 | 211486 |
| isolation of an avian erythrocyte protein possessing adp-ribosyltransferase activity and capable of activating adenylate cyclase. | an adp-ribosyltransferase was purified approximately 500-fold from the supernatant fraction of turkey erythrocytes. the enzyme hydrolyzed [carbonyl-(14)c]nad to adp-ribose and [carbonyl-(14)c]nicotinamide at a low rate. nicotinamide formation from nad was enhanced by arginine methyl ester > d-arginine approximately l-arginine > guanidine; lysine, histidine, and citrulline were ineffective. incubation of [adenine-u-(14)c]nad and arginine methyl ester or arginine with the purified enzyme resulted ... | 1978 | 211502 |
| cyclic-amp content in escherichia coli b/b as affected by n1-(delta 2-isopentyl)adenine. | n6-(delta 2-isopentenyl)adenine, like other cytokinins, does not detectably modify escherichia coli growth, but strongly affects cellular levels of camp. a substantial delay of the highest level of intracellular camp, a reduction to about one half of such maximum level, and a slight increase of camp secreted into the medium are reported. | 1978 | 211751 |
| [ultramicroscopic structure of the cyst wall of entamoeba invadens, e. histolytica and e. coli]. | the ultrastructure of the wall of e. invadens cysts induced in axenic cultures was compared by transmission electron microscopy of thin sections, with that of e. histolytica and e. coli cysts obtained from feces of human asymptomatic carriers. the cyst wall of the three species studied had similar ultrastructural features; in all, the wall was composed mainly by the aggregation of filaments adjacent to the plasma membrane. the cytoplasmic components which might be involved in the synthesis and d ... | 1978 | 211940 |
| the utilisation of d-galactonate and d-2-oxo-3-deoxygalactonate by escherichia coli k-12. biochemical and genetical studies. | | 1978 | 211976 |