| structure of the lipopolysaccharide from an escherichia coli heptose-less mutant. i. chemical degradations and identification of products. | the structure of lipopolysaccharide from a heptose-less mutant of escherichia coli k-12 has been investigated. lipopolysaccharide isolated from 32p-labeled cells was treated with mild alkali to yield two separable components: [oh-lps]-i (approximately 70%) and [oh-lps]-ii (approximately 30%). mild acidic treatment of [oh-lps]-i gave mainly a product which was identified as (4-o-phosphoryl-n-beta-hydroxymyristyl-d-glucosaminyl)-beta(1 leads to 6)-n-beta-hydroxymyristyl-d-glucosamine 1-phosphate ( ... | 1979 | 221486 |
| nad-dependent adp-ribosylation of arginine and proteins by escherichia coli heat-labile enterotoxin. | escherichia coli heat-labile enterotoxin (labile toxin, lt) catalyzed the hydrolysis of nad to adp-ribose and nicotinamide and the adp-ribosylation of arginine (moss, j., and richardson, s.h. (1978) j. clin. invest. 62, 281-285). analysis of the product of the adp-ribosylation of arginine by nuclear magnetic resonance spectroscopy indicated that the reaction was stereospecific and resulted in the formation of alpha-adp-ribosyl-l-arginine. this reaction product rapidly anomerized to yield a mixtu ... | 1979 | 221495 |
| cell composition and drug resistance in escherichia coli. | resistance of micro-organisms to antibacterial drugs which cannot be attributed to a genetic change may often be traced to phenotypic changes in cell composition caused by differing growth conditions. to investigate an aspect of this attribute e. coli nctc 86 was grown on a simple synthetic media containing alanine or cystine and, as a control, in nutrient broth. cells grown on the media containing alanine and cystine showed a depleted total extractable lipid and phospholipid content. phosphatid ... | 1978 | 221791 |
| modulation of the two promoters of the galactose operon of escherichia coli. | the gal operon of escherichia coli is controlled by two independent promotors--one is activated and the other inhibited by cyclic amp and cyclic amp receptor protein. the two promotors are modulated, however, by the same operator locus and receptor protein. | 1979 | 221830 |
| unusual location and function of the operator in the escherichia coli galactose operon. | the operator of the gal operon is located about 60 base pairs preceding the startpoints of the transcription of the two gal promoters. this location contrasts with the location of the operator in other phage or bacterial operons where the repressor binds more closely to the respective transcription initiation sites. models explaining how the repressor-operator interactions may control the two gal promoters are presented. | 1979 | 221831 |
| genome organization of retroviruses. iii. restriction endonuclease cleavage maps of mouse sarcoma virus double-stranded dna synthesized in vitro. | genome length complementary dna (cdna) transcripts were synthesized in vitro by using purified virions of a cloned isolate of mouse sarcoma virus (msv clone 124). the cdna transcripts were converted to double-stranded form by utilizing dnase-digested calf thymus dna primers and e. coli dna polymerase i. restriction endonucleases sal i, hind iii, hpa i, bgl ii and xba i were found to cleave the msv double-stranded dna once to generate two fragments, whereas restriction endonucleases bgl i and hae ... | 1979 | 221890 |
| enzyme-catalyzed dna unwinding: studies on escherichia coli rep protein. | replication in vitro of the replicative form (rf) i dna of bacteriophage varphix174 requires the phage-induced cistron a (cisa) protein, the host rep protein, dna-binding protein, atp, and dna polymerase iii plus replication factors. the rep protein is a single-stranded dna-dependent atpase. in this paper we show that varphix174 rf i dna cut by the cisa protein acts as a duplex dna cofactor for the rep protein atpase activity, provided that dna-binding protein is present. in this latter reaction ... | 1979 | 221901 |
| an escherichia coli mutant defective in single-strand binding protein is defective in dna replication. | an escherichia coli mutant, temperature-sensitive for dna synthesis in vivo and in vitro, is defective in single-strand binding protein (ssb; dna-binding protein). conversion of phage g4 single strands to the duplex form is defective in crude enzyme fractions of the mutant and is complemented by pure wild-type ssb. radioimmunoassays of mutant extracts show normal levels of material crossreacting with anti-ssb antibody. ssb purified to homogeneity from the mutant is active, with lower specific ac ... | 1979 | 221903 |
| hepatic heme metabolism and its control. | | 1979 | 222077 |
| detection of enterotoxigenicity and attachment factors in escherichia coli strains of human, porcine and bovine origin; a comparative study. | porcine and bovine strains of e. coli suspected to be enterotoxigenic, were tested for heat-labile enterotoxin (lt) production by means of a test measuring the stimulation of the synthesis of 3151 cyclic adenosin monophosphate (camp test) and rounding mouse adrenal tumor y1 cells (y1 test), and for heat-stable enterotoxin (st) production by means of the baby mouse test (bm test). the test results were compared with those of the ligated gut test (lg test) using pig and calf intestine. one hundred ... | 1979 | 222093 |
| the interactions of adenylates with allosteric citrate synthase. | evidence is presented that a number of derivatives of adenylic acid may bind to the allosteric nadh binding site of escherichia coli citrate synthase. this evidence includes the facts that all the adenylates inhibit nadh binding in a competitive manner and that those which have been tested protect an enzyme sulfhydryl group from reaction with 5,5'-dithiobis-(2-nitrobenzoic acid) in the same way that nadh does. however, whereas nadh is a potent inhibitor of citrate synthase, most of the adenylate ... | 1979 | 222408 |
| e. coli dna binding protein hu forms nucleosomelike structure with circular double-stranded dna. | the incubation of the e coli dna binding protein hu with relaxed circular sv40 dna in the presence of pure nicking-closing enzyme introduces up to 18 negative superhelical turns in the dna molecules as measured by agarose gel electrophoresis. the maximal density of supercoiling is obtained at a hu-dna mass ratio of 1. reconstituted dna-hu complexes prefixed with glutaraldehyde appear as condensed circular structures having an average of 14 "beads" per circular sv40 dna molecule, with a "bead" di ... | 1979 | 222478 |
| methionyl-trna synthetase from escherichia coli. inactivation and labeling by periodate-treated initiator trna. | both the aminoacylation and isotopic atp-ppi exchange activities of native and trypsin-modified methionyl-trna synthetases from escherichia coli are specifically inactivated by incubation in the presence of periodate-treated initiator trna met. the inactivation proceeds through the formation of a reversible schiff's base between the epsilon-amino group of a lysine within the catalytic center of the enzyme and the 2',3'-aldehyde groups created at the 3'-terminal ribose of trna. the schiff's base ... | 1979 | 222589 |
| adenosine, nad and fad can initiate template-dependent rna synthesis catalyzed by escherichia coli rna polymerase. | | 1979 | 222618 |
| effect of cyclic adenosine 3',5'-monophosphate antagonists on endotoxin-induced inhibition of human neutrophil chemotaxis. | we reported previously that escherichia coli endotoxin inhibited human neutrophil chemotaxis toward c5a. this effect of endotoxin was antagonized by anti-inflammatory steroids. we now report that dibutyryl cyclic adenosine 3',5'-monophosphate, prostaglandin e1, isoproterenol, and cholera toxin also antagonize the suppression of chemotaxis by endotoxin. each compound inhibited the effect of endotoxin in a dose-dependent fashion. to be effective, each compound except cholera toxin had to be presen ... | 1979 | 222686 |
| effects of 8-substituted analogs of cyclic adenosine 3',5'-monophosphate on in vivo and in vitro syntheses of beta-galactosidase in escherichia coli. | several 8-substituted alkylthio and alkylamino cyclic adenosine 3',5'-monophosphate (camp) derivatives were tested for their ability to stimulate beta-galactosidase synthesis in estherichia coli in vivo and in vitro and to inhibit the camp phosphodiesterase activity of e. coli. stimulation of beta-galactosidease synthesis in vivo by camp derivatives decreased with increasing length of the unbranched carbon chain of the substituent. on the other hand, the stimulation in vitro was increased as the ... | 1979 | 222725 |
| aromatic amino acid biosynthesis: regulation of shikimate kinase in escherichia coli k-12. | starvation of cells of escherichia coli k-12 for the aromatic amino acids results in an increased rate of synthesis of shikimate kinase activity. the two controlling amino acids are tyrosine and tryptophan, and starvation for both results in derepression. the product of the regulator gene tyrr also participates in this control, and shikimate kinase synthesis was depressed in tyrr mutants. chromatography of cell extracts on diethylaminoethyl-sephadex allowed partial separation of two shikimate ki ... | 1979 | 222728 |
| orientation of the guanine operon of escherichia coli k-12 by utilizing strains containing guab-xse and guab-upp deletions. | temperature induction of an escherichia coli strains with lambda ci1857 integrated in the guab gene has been used to produce strains containing chromosomal deletions extending into the xse and upp genes. by utilizing strains containing these deletions, it has been possible to order the genes in the guanine operon with respect to the xsea and upp genes. the order of the genes in this region is glya-hiss-xsea-guao-guab-guaa-purg-upp-purc. | 1979 | 222730 |
| cardiolipin accumulation in the inner and outer membranes of escherichia coli mutants defective in phosphatidylserine synthetase. | mutants of escherichia coli defective in phosphatidylserine synthetase (pss) make less phosphatidylethanolamine than normal cells, and they are temperature sensitive for growth. we have isolated a new mutant, designated ra2021, which is better than previously available strains in that the residual phosphatidylethanolamine level approaches 25% after 4 h at 42 degrees c. the total amount of phospholipid normalized to the density of the culture is about the same in ra2021 (pss-21) as in the isogeni ... | 1979 | 222736 |
| antipain lethality to escherichia coli: dependence upon cyclic adenosine 3',5'-monophosphate and its receptor protein. | antipain kills escherichia coli k-12 cells in an exponential manner beginning 1 h after its addition. mutant strains, delta cya and crp, which are unable to synthesize cyclic adenosine 3',5'-monophosphate (camp) and the camp receptor protein, respectively, are not affected. addition of camp (5 mm) to antipain-treated mutant strains causes killing of delta cya cells, but not crp cells. thus the lethal effect of antipain is dependent upon camp and its receptor protein. | 1979 | 222740 |
| control of membrane lipid synthesis in escherichia coli during growth and during the stringent response. | the regulation of phospholipid synthesis in cells of escherichia coli was studied in vivo during growth and during the stringent response to amino acid starvation. strains harboring the hybrid plasmid plc44-14 (clark, l., and carbon, j. (1976) cell 9, 91-99), which had increased levels of glycerophosphate acyltransferase, were used to study the involvement of this enzyme in the control of phospholipid synthesis. in addition, regulation was studied by measuring the levels of three early intermed ... | 1979 | 222765 |
| diarrhea and rotavirus infection associated with differing regimens for postnatal care of newborn babies. | surveillance of 2,041 babies born during 4 winter months in one obstetric hospital in melbourne, australia, showed that 215 developed acute diarrhea during the first 2 weeks of life. babies requiring special care from birth had a high incidence of sporadic diarrhea (36%). the incidence of diarrhea among healthy full-term babies was low if they were "rooming-in" with their mothers (2 to 3%) but high if they were housed in communal nurseries (29%). the most important factor influencing incidence o ... | 1979 | 222807 |
| gangliosides sensitize unresponsive fibroblasts to escherichia coli heat-labile enterotoxin. | chemically transformed mouse fibroblasts did not raise their cyclic amp level in response to escherichia coli heat-labile enterotoxin. these fibroblasts did, however, incorporate exogenous mono-, di-, and trisialogangliosides. after the uptake of monosialoganglioside galactosyl-n-acetylgalactosaminyl-[n-acetylneuraminyl]-galactosylglucosylceramide (gm1), the cells responded to e. coli heat-labile enterotoxin. the di- and trisialogangliosides were considerably less effective. gm1, the putative ch ... | 1979 | 222809 |
| transcription of nucleosomal dna in sv40 minichromosomes by eukaryotic and prokaryotic rna polymerases. | sv 40 minichromosomes can be transcribed by prokaryotic and eukaryotic rna polymerases. size analysis of transcripts indicated that dna in nucleosomes was accessible for transcription by both enzymes. sedimentation of the transcription complex showed that minichromosomes which were being transcribed had a full complement of nucleosomes. strand selection by e. coli rna polymerase was reduced by the presence of nucleosomes. no region of sv 40 dna was preferentially transcribed on minichromosomes b ... | 1979 | 223131 |
| [pseudomonas aeruginosa melanin]. | the epr, ir, uv and visible absorption spectra of a melanin-like pigment from p. aeruginosa were studied. by the whole complex of the spectral characteristics the pigment may be classified as belonging to the melanin group. the study of the antibiotic properties of the pigment showed that it did not inhibit the growth of p. aeruginosa and e. coli. still, it possessed some antistaphylococcal activity. | 1979 | 223498 |
| determination of rate-limiting steps of escherichia coli carbamoyl-phosphate synthase. rapid quench and isotope partitioning experiments. | | 1979 | 223631 |
| studies on the methylation of cytoplasmic ribosomal rna from cultured higher plant cells. | the methylation of cytoplasmic ribosomal rna of cultured sycamore cells (acer pseudoplatanus l.) was investigated. labelled 17-s and 26-s rrna were prepared from cells that had been incubated with either [32p]phosphate, [me-3h]methionine or [me-14c]methionine. ion-exchange resin chromatography of 0.3 m koh or 1 m hcl hydrolysates and two-dimensional chromatographic analyses of phosphodiesterase plus phosphatase digests of 17-s and 26-s rrna were performed. 17-s and 26-s rrna contain 49 and 91 me ... | 1979 | 223845 |
| suppression of induced beta-galactosidase synthesis by cysteamine and its reversion by gamma-irradiation in the presence of ascorbate. | the induced synthesis of beta-galactosidase in e. coli was found to be inhibited by cysteamine. this inhibitory effect of the sh compound was antagonized by the addition of ascorbate followed by gamma-irradiation with relatively low doses. the camp level which, it has been suggested, plays a role in the radioprotective action of cysteamine, is stabilized by ascorbate against changes induced by irradiation. | 1978 | 224000 |
| biophysical properties of a major membrane phospholipid, dielaidoylphosphatidylethanolamine, found in an escherichia coli fatty acid auxotroph. | dielaidoylphosphatidylethanolamine, a principal lipid component of membranes of escherichia coli fatty acid auxotrophs enriched in elaidic acid, has been studied by paramagnetic resonance, fluorescence, and calorimetric methods. epr measurements with perdeutero-di-tert-butylnitroxide and 2,2,6,6-tetramethyl piperidine-1-oxyl indicate that, when dispersed in aqueous media, this phospholipid undergoes an abrupt order leads to disorder transition at 37.5 degrees c and 36.5 c, respectively. a simila ... | 1979 | 224048 |
| contribution of cyclic adenosine 3':5'-monophosphate to the regulation of bacterial glycogen synthesis in vivo. effect of carbon source and cyclic adenosine 3':5'-monophosphate on the quantitative relationship between the rate of glycogen synthesis and the cellular concentrations of glucose 6-phosphate and fructose 1,6-diphosphate in escherichia coli. | when either fructose, glycerol, or succinate served as a sole source of carbon and energy in nitrogen-starved cultures of escherichia coli w4597(k) the values of the kinetic constants of the equation that expresses the relationship between glycogen synthesis and hexose phosphates were different from the values observed when glucose was the sole source of carbon and energy. addition of glucose during either exponential growth or nitrogen starvation to a culture using one of the other carbon sourc ... | 1979 | 224050 |
| phosphatidylserine synthase from escherichia coli. the role of triton x-100 in catalysis. | | 1979 | 224052 |
| molecular cloning of polyoma virus dna in escherichia coli: oncogenicity testing in hamsters. | inoculation of suckling hamsters with 2 x 10(8) live cells of escherichia coli k12 strain chi1776, carrying the complete genome of polyoma virus in a recombinant plasmid, failed to induce tumors in any of 32 recipients. also, lambda phage dna and particles with a monomeric insert of polyoma dna did not induce tumors. purified recombinant plasmid dna, as well as phage particles and dna containing a head-to-tail dimer of polyoma dna, showed a low degree of oncogenicity, comparable to that of polyo ... | 1979 | 224458 |
| magnesium ion dependent rabbit skeletal muscle myosin guanosine and thioguanosine triphosphatase mechanism and a novel guanosine diphosphatase reaction. | the mechanism of the mg2+-dependent myosin subfragment 1 catalyzed hydrolysis of gtp and 2-amino-6-mercapto-9-beta-ribofuranosylpurine 5'-triphosphate (thiogtp) has been investigated by rapid-reaction techniques. the myosin was isolated from rabbit skeletal muscle. the steady-state intermediate of these reactions consists pre-dominantly of a protein-substrate complex unlike the myosin subfragment 1 atpase reaction which has a protein-products complex as the principal steady-state component. the ... | 1979 | 224906 |
| role of metal cofactors in enzyme regulation. differences in the regulatory properties of the escherichia coli nicotinamide adenine dinucleotide specific malic enzyme depending on whether mg2+ or mn2+ serves as divalent cation. | | 1979 | 224913 |
| mechanism of phenylalanyl-trna synthetase of escherichia coli k. 10. modulation of catalytic properties by magnesium. | the association of phenylalanylptrna and mg2+ follows a biphasic concentration dependence as indicated by the active site directed fluorescent indicator 2-p-toluidinyl-naphthalene-6-sulfonate. the macroscopic dissociation constants are 0.16 +/- 0.03 and 4.1 +/- mm. the effect of mg2+ on the association of enzyme and mgatp, on the synergistic binding of mgatp and l-phenylalaninol, and on the pre-steady-state synthesis and pyrophosphorolysis of the enzyme-phenylalanyladenylate complex in the absen ... | 1979 | 224916 |
| relationship of growth temperature and thermotropic lipid phase changes in cytoplasmic and outer membranes from escherichia coli k12. | purified cytoplasmic and outer membranes isolated from cells of wild type escherichia coli grown at 12, 20, 37 and 43 degrees c were labelled with the fatty acid spin probe 5-doxyl stearate. electron spin resonance spectroscopy revealed broad thermotropic phase changes. the inherent viscosity of both membranes was found to increase as a function of elevated growth temperature. the lipid order to disorder transition in the outer membrane but not the cytoplasmic membrane was dramatically affected ... | 1979 | 224924 |
| oral rehydration and maintenance of children with rotavirus and bacterial diarrhoeas. | the outcome of administering ort (oral rehydration therapy) to 62 infants admitted to a costa rican hospital with acute rotavirus or bacterial diarrheas and with 5-10% dehydration was described. 94% of the infants were successfully treated by administering only ort. there were no significant differences in the success rates for rotavirus diarrhea patients and for various bacterial diarrhea patients. success rates were 92% for rotavirus patients, 93% for escherichia coli patients, 96% for idio ... | 1979 | 225048 |
| [cooperative non-specific binding of the cyclic adenosine 3'--5'-monophosphate receptor protein (crp) from escherichia coli to double-stranded thymus and lambda pgal dna]. | either free or combined with camp, crp binds cooperatively to double-stranded thymus and lambda pgal dna. the affinity of crp for both dnas in these non-specific interactions is increased by camp without noticeable change in the degree of cooperativity. values of the intrinsic association constant, cooperativity parameter, and site size of dna were determined from ultracentrifugal investigations under near-physiological ionic conditions. | 1979 | 225052 |
| dna replication proteins of escherichia coli and phage lambda. | | 1979 | 225103 |
| the rep protein of escherichia coli: interaction with dna and other proteins. | | 1979 | 225105 |
| dna-dependent atpases from escherichia coli k12. | four dna-dependent atpases have been isolated from e. coli extracts. atpases i and iii, both sensitive to nem, require denatured dna but differ in their heat sensitivity, elution from deae-cellulose, and sedimentation coefficient. atpases ii and iv are both resistant to nem. atpase ii requires partially denatured dna, whereas atpase iv can be stimulated by ss dna. atpase i is a dna-unwinding enzyme; atpase ii may be involved in recombination. | 1979 | 225106 |
| structure and activities of escherichia coli dna gyrase. | | 1979 | 225110 |
| the lactoperoxidase-thiocyanate-hydrogen peroxide antibacterium system. | lactoperoxidase present in various secretions oxidizes thiocyanate (scn-) in the presence of h2o2 to an unstable oxidation product--hypothiocyanite (oscn-), which is bactericidal for enteric pathogens including multiple antibiotic resistant strains of e. coli. the system damages the inner membrane causing leakage and cessation of uptake of nutrient, leading eventually to death of the organisms and lysis. the possible involvement of o2- and 1o2 is discussed. | 1978 | 225143 |
| superoxide dismutases: defence against endogenous superoxide radical. | attempts to measure the rate of o2- production, in whole cells or in intact subcellular organelles, are frustrated by the endogenous superoxide dismutase (sod). streptococcus faecalis contains a single manganese-sod which was isolated and used as an antigen in the rabbit. a precipitating and inhibiting antibody was obtained and used to suppress the sod in crude lysates of s. faecalis. it allowed the demonstration that 17% of the total oxygen uptake by such lysates, in the presence of nadh, was a ... | 1978 | 225147 |
| tgs and crr: genes involved in catabolite inhibition and inducer exclusion in escherichia coli. | | 1979 | 225210 |
| studies on regulatory functions of malic enzymes. iv. effects of sulfhydryl group modification on the catalytic function of nad-linked malic enzyme from escherichia coli. | reactions catalyzed by nad-linked malic enzyme from escherichia coli were investigated. in addition to l-malate oxidative decarboxylase activity (activity 1) and oxaloacetate decarboxylase activity (activity 2), the enzyme exhibited oxaloacetate reductase activity (activity 3) and pyruvate reductase activity (activity 4). optimum ph's for activities 3 and 4 were 4.0 and 5.0, and their specific activities were 1.7 and 0.07, respectively. upon reaction with n-ethylmaleimide (nem), activity 1 decre ... | 1979 | 225306 |
| evidence for bactericidal activity of polymorphonuclear leukocytes without phagocytosis. | the relationship between phagocytosis and bactericidal action of polymorphonuclear leukocytes was examined by comparing the functions of cytochalasin d-treated leukocytes with those of the control. measurement of phagocytotic and bacterial dna-degrading activities using escherichia coli prelabeled with [3h]thymidine revealed that phagocytosis and bacterial dna degradation were inhibited by treatment with cytochalasin d to about 50 and 10% of the control, respectively. nevertheless, the bacterici ... | 1979 | 225308 |
| expression of the lac operon in rna polymerase mutants of escherichia coli k12. | three temperature-sensitive mutant strains for rna polymerase beta or beta' subunits (carrying mutations tsx, a2r7 and r120) were used in order to investigate the dependence of the induced lac expression on stimulation by cyclic amp after the shift to non-permissive temperature. high temperature lowered the rate of beta-galactosidase synthesis. however, the low rate of synthesis could be strongly increased by cyclic amp (30, 2.4 and 5.7-fold increases for tsx, a2r7 and r120 mutants, respectively ... | 1979 | 225641 |
| single strands induce reca protein to unwind duplex dna for homologous pairing. | single-stranded dna, whether homologous or not, stimulates purified escherichia coli reca protein to unwind duplex dna. this helps to explain how reca promotes a search for homology in genetic recombination. as oligodeoxynucleotide also stimulate unwinding, a common mechanism may relate the function of reca protein in recombination to other functions (sos) induced by oligonucleotides. | 1979 | 225671 |
| fractionation of connective-tissue-activating factors from the culture medium of silica-treated macrophages. | the medium of cultured, sio2-treated peritoneal macrophages contained a factor which enhances the incorporation of labelled proline to collagen and other proteins in granulation tissue slices, cells and polysomes. simultaneously, the activity of alkaline rnase in the whole medium was decreased in comparison with the corresponding control. polyvinylpyridine-n-oxide, pvno, protected the macrophages against sio2. latex-particles and e. coli lipopolysaccharide decreased the rnase activity in the mac ... | 1979 | 225924 |
| [effects of ampicillin and cefazolin combined with mecillinam (author's transl)]. | combination effects of mecillinam + ampicillin and mecillinam + cefazolin were investigated by the cross diffusion test and by the kinetics of bactericidal action. synergism was found by cross diffusion in about 50% of strains of e. coli, klebsiella and proteus. sensitivity against ampicillin was correlated with synergism. in mecillinam-resistant strains, synergism is usually absent. the combination of ampicillin or cefazolin with mecillinam leads to bactericidal acceleration; the effects are co ... | 1978 | 226099 |
| mechanistic studies on deoxyribonucleic acid dependent ribonucleic acid polymerase from escherichia coli using phosphorothioate analogues. 1. initiation and pyrophosphate exchange reactions. | the diastereomers of adenosine 5'-o-(1-thiotriphosphate) (atp alpha s) and adenosine 5'-o-(2-thiotriphosphate) (atp beta s) can replace adenosine triphosphate (atp) in the initiation reaction catalyzed by deoxyribonucleic acid (dna) dependent ribonucleic acid (rna) polymerase from escherichia coli. in both cases, the sp diastereomer is a better initiator than the rp isomer. the diasteromers of 3'-uridyl 5'-adenosyl ,o-phosphorothioate [up(s)a] can replace upa in the primed initiation reaction ca ... | 1979 | 226121 |
| involvement of eucaryotic deoxyribonucleic acid polymerases alpha and gamma in the replication of cellular and viral deoxyribonucleic acid. | in an effort to identify the deoxyribonucleic acid (dna) polymerase activities responsible for mammalian viral and cellular dna replication, the effect of dna synthesis inhibitors on isolated dna polymerases was compared with their effects on viral and cellular dna replication in vitro. dna polymerase alpha, simian virus 40 (sv40) dna replication in nuclear extracts, and cv-1 cell (the host for sv40) dna replication in isolated nuclei all responded to dna synthesis inhibitors in a quantitatively ... | 1979 | 226127 |
| the atp synthetase of escherichia coli k12: purification of the enzyme and reconstitution of energy-transducing activities. | the atp synthetase of escherichia coli k12 was purified by a simple procedure. the dicyclohexylcarbodiimide-sensitive atpase activity was enriched 21-fold. the atp synthetase preparation contained the eight polypeptides (alpha, beta, gamma, a,delta, b,espilon, c) of the enzyme and a residual contamination (4% of the total protein) as shown by dodecylsulfate/polyacrylamide electrophoresis. the polypeptide c was specifically labelled with [14c]dicyclohexylcarbodiimide. energy-transducing activitie ... | 1979 | 226359 |
| cyclic amp control of the envelope growth in escherichia coli: envelope morphology of the mutants in cya and crp genes. | | 1979 | 226474 |
| purification of the t4 gene 32 protein free from detectable deoxyribonuclease activities. | detailed procedures are presented which allow reproducible preparation of t4 gene 32 protein, a helix-destabilizing protein essential for dna replication and genetic recombination in t4 bacteriophage-infected escherichia coli cells. although 32 protein can be purified to better than 99% homogeneity by any one of several procedures, these methods have been developed to remove trace amounts of contaminating deoxyribonucleases, which are present in high levels in the original infected cells. two al ... | 1979 | 226522 |
| phosphorylation of 5-iodo-5'-amino-2',5',dideoxyuridine by herpes simplex virus type 1 encoded thymidine kinase. | herpes simplex virus type 1 (hsv-1) encoded thymidine kinase converts 5-iodo-5'-amino-2',5'-dideoxyuridine (aidurd), a highly specific anti-herpes agent, into the 5'-diphosphate (aidudp) derivative in vitro. aidudp was identified by its acid lability, sensitivity to alkaline phosphatase hydrolysis, chromatographic behavior, and ratio of double isotope (125i, 32p) labeling. atp, but not amp, is a phosphate donor, and the direct transfer of the beta and gamma phosphate of atp as pyrophosphate to a ... | 1979 | 226542 |
| requirements for synthesis of ribonucleic acid primers during lagging strand synthesis by the dna polymerase and gene 4 protein of bacteriophage t7. | dna polymerase and gene 4 protein of bacteriophage t7 catalyze dna synthesis on duplex dna templates. synthesis is initiated at nicks in the dna template, and this leading strand synthesis results in displacement of one of the parental strands. in the presence of ribonucleoside 5'-triphosphates the gene 4 protein catalyzes the synthesis of oligoribonucleotide primers on the displaced single strand, and their extension by t7 dna polymerase accounts for lagging strand synthesis. since all the olig ... | 1979 | 226544 |
| human rotavirus in an adult population with travelers' diarrhea and its relationship to the location of food consumption. | the role of human rotavirus in adult diarrhea was evaluated in 164 newly arrived us students attending summer school at an urban mexican university. rotavirus was identified in stool samples by electron microscopy. rotavirus was found in 26 of 109 students with diarrhea (24%) and in 8 of 55 asymptomatic control students (15%). although bacterial pathogens were recovered from virus positive students with diarrhea, viral shedding also occurred independently of other agents. clinical disease in stu ... | 1979 | 226656 |
| synthesis and biological properties of n2-substituted spin-labeled analogues of actinomycin d. | we have synthesized n2-[4-(2,2,6,6-tetramethyl-1-piperidinyloxy)]actinomycin d and the related 1,2-diaminoethane and 1,3-diaminopropane derivatives and evaluated their biological properties. binding studies with the spin-labeled actinomycin d analogues and dna were carried out by using circular dichroism, electron spin resonance, and thermal denaturation. these studies have suggested that the derivatives bind to dna and that their dna-binding modes are similar but not identical. spin-labeled act ... | 1979 | 226705 |
| characterization of a plasmid mutation affecting maintenance, transfer and elimination by novobiocin. | we have isolated a mutant h group plasmid temperature-sensitive for plasmid maintenance. unlike the wild type plasmid (psd114), the mutant (pdt4) was eliminated at 37 degrees c and also at 30 degrees c after novobiocin treatment. the mutant plasmid interfered with host cell growth at the non-permissive temperature. conjugative transfer of the mutant was reduced at 30 degrees c compared to the wild-type plasmid. introduction of a coumermycin-novobiocin resistance dna gyrase (cou) mutation into es ... | 1979 | 226836 |
| enterotoxins of escherichia coli and epilepsy. | evidence exists that cyclic nucleotides play an important role in the stabilisation of developing synapses during the early postnatal period, and later on participate in the generation of the slow excitatory and inhibitory postsynaptic potentials. it is postulated that enterotoxins of escherichia coli, due to their long-lasting and specific action on cyclic nucleotide-dependent processes, provide a unique mechanism for selective impairment of synaptogenesis in the abscence of cell loss. therefor ... | 1979 | 226849 |
| the glucocorticoid domain of response: measurement of pleiotropic cellular responses by two-dimensional gel electrophoresis. | in this article, we have provided two examples of pleiotropic regulation by specific effector molecules as assayed by two-dimensional gel electrophoresis. in one case, catabolite repression in the bacterium escherichia coli was examined by measuring the response to cyclic camp. in the other, the effect of dexamethasone on the rate of synthesis of over a thousand cell proteins was analyzed in htc cells. it was found that in e. coli, camp regulates the synthesis of about 10 percent of the cell's p ... | 1979 | 226869 |
| t4 dna topoisomerase: a new atp-dependent enzyme essential for initiation of t4 bacteriophage dna replication. | a novel atp-dependent dna topoisomerase which makes reversible double-strand breaks in the dna double helix has been purified to near homogeneity from t4 bacteriophage-infected escherichia coli cells. genetic data suggest that this activity is essential for initiating t4 dna replication forks in vivo. | 1979 | 226889 |
| cyclic amp as a modulator of polarity in polycistronic transcriptional units. | the degree of natural polarity in the lactose and galactose operons of escherichia coli is affected by adenosine 3',5'-cyclic monophosphate (camp). this effect, mediated by the camp receptor protein, is exerted at sites distinct from the promoter. experiments performed with a mutant bearing a thermosensitive rho factor activity indicate that camp relieves polarity by interfering with transcription termination. conflicting results in the literature concerning the role of camp receptor protein and ... | 1979 | 226959 |
| t4 dna-delay proteins, required for specific dna replication, form a complex that has atp-dependent dna topoisomerase activity. | under some conditions, t4 dna replication requires the products of the dna-delay genes, genes 39, 52, 58, and 60. by using an in vitro complementation assay that stimulates dna replication in t4 39(-)-infected cell extracts, t4 gene 39 protein has been purified. the purified fraction also contains complementing activities for t4 genes 52 and 60. on sodium dodecyl sulfate/polyacrylamide gel analysis the purified preparation exhibits three protein components: a 51,000-dalton protein corresponding ... | 1979 | 226976 |
| cloning of the active thymidine kinase gene of herpes simplex virus type 1 in escherichia coli k-12. | a herpes simplex virus dna fragment that is produced by digestion with bamhi endonuclease and carries the thymidine kinase (tk; atp:thymidine 5'-phosphotransferase, ec 2.7.1.21) gene has been cloned in escherichia coli. a recombinat plasmid, pfg5, has been analyzed extensively and a detailed restriction map is presented. pfg5 dna efficiently transforms tk- mouse l cells. the tk coding sequence in the cloned fragment has been localized and a smaller recombinant plasmid, pag0, also carrying an act ... | 1979 | 226978 |
| [acute infectious gastroenteritis. etiology and its correlation with clinical manifestations and fecal mucus]. | 343 children with acute diarrhea were studied from january 1976 to september 1977. rotavirus was the agent most frequently isolated (18 per cent) followed by shigella (12 per cent) and salmonella (10 per cent). enterotoxigenic e. coli was identified in 8 per cent and invasive e. coli only in two cases. 80 per cent of isolated rotavirus fell in the neonate group and 25 per cent in the infant group. diarrhea caused by rotavirus had a short duration, fever was negligible and abundant liquid stools ... | 1979 | 227338 |
| effect of o-sulphate groups in lactose and n-acetylneuraminyl-lactose on their enzymic hydrolysis. | 1. lactose 6'-o-sulphate, n-acetylneuraminyl-(alpha 2 leads to 3)-d-lactose 6'-o-sulphate, n-acetylneuraminyl ?-o-sulphate-(alpha 2 leads to 3)-d-lactose 6'0-o-sulphate, n-acetylneuraminyl ?-o-sulphate-(alpha 2 leads to 6)-d-lactose and n-acetylneuraminyl-(alpha 2 leads to 3)- and -(alpha 2 leads to 6))-lactose 6'-o-sulphate were prepared by chemical sulphation of lactose, n-acetylneuraminyl-lactose and tis isomers by using pyridine-so3 reagent. 2. significant kinetic differences were observed i ... | 1979 | 227364 |
| further studies on the antipyretic action of polymyxin b in pyrogen-induced fever. | a study of the antipyretic effect of polymyxin b was undertaken to determine how this agent reduces fever in rabbits. it involved the effects of the drug: (1) on fever induced by exogenous pyrogenes (e. coli lipopolysaccharide, synthetic double-stranded ribonucleic acid, sodium nucleinate from yeast) and leucocytic pyrogen, (2) on the release of endogenous pyrogen in vivo and in vitro, and (3) on leucocytic and exogenous pyrogens in vitro. the results indicate that polymyxin b produces an antipy ... | 1978 | 227419 |
| partial purification and characterization of a ribonucleic acid n2-guanine methyltransferase associated with avian myeloblastosis virus. | a nucleic acid methylase, n2-guanine ribonucleic acid (rna) methyltransferase, which is associated with type c rna tumor viruses, has been purified from avian myeloblastosis virions by gel filtration on sephadex g-200, followed by chromatography on hydroxylapatite. the molecular weight estimated by gel filtration is 220 000, and the methylase activity has a ph optimum of 7.6--7.9. magnesium and ammonium ions both stimulate activity 1.5-fold at 9.5 mm and 0.36 m, respectively, but apparently neit ... | 1979 | 227452 |
| dephosphorylation of purine mononucleotides by alkaline phosphatases. substrate specificity and inhibition patterns. | three purine mononucleotides, adenosine-, inosine- and guanosine monophosphate, were used as substrates at ph 7.4 and at 10.4 for three alkaline phosphatases (orthophosphoric-monoester phosphohydrolase (acid optimum), ec 3.1.3.1) containing similar phosphate-binding serine groups at their esteratic sites. substrate specificity was found for the enzymes from calf intestine and bovine liver. alkaline phosphatase from escherichia coli was nonspecific. a substrate-dependent and pronounced inhibition ... | 1979 | 227468 |
| regulation of transcription by dna-bound non-histone nuclear proteins. | purified non-histone proteins from mouse mammary cells bind specifically to homologous dna or chromatin. complexes of non-histone protein with dna or chromatin, isolated on agarose columns, were transcribed with both escherichia coli rna polymerase and rna polymerase b from calf thymus. the fact that complexing of dna with non-histone proteins increases transcription by e. coli rna polymerase but not by rna polymerase b suggests different mechanisms of transcription by these two enzymes. similar ... | 1979 | 227684 |
| native escherichia coli hu protein is a heterotypic dimer. | | 1979 | 227733 |
| isolation and investigation of the escherichia coli mutant with the deletion in the ptsh gene. | | 1979 | 227739 |
| cloning the argf gene from escherichia coli k-12 with simian virus 40. | we have inserted a gene coding for ornithine transcarbamylase (otcase) from escherichia coli k-12 into the late gene region of simian virus 40 (sv40) dna and propagated the hybrid molecules as free episomes or by co-infection with an sv40 tsa helper virus. in the first case, the e. coli argf gene was inserted via the ecori and bamhi termini in the late gene region of sv40 and the recombinant molecules were used to transfect monkey kidney cells. the hybrid dna, which was too large to be encapsida ... | 1979 | 227771 |
| in vitro combination of mecillinam with cephradine or amoxycillin for organisms resistant to single agents. | of 36 multi-resistant gram-negative bacilli isolated from different cases of urinary tract infection, 18 strains of escherichia coli, klebsiella, enterobacter, proteus, providencia and serratia with the exception of acinetobacter species showed synergy when mecillinam was combined with cephradine or amoxycillin in the ratio of 1:1. combination with cephradine was synergistic on sixteen occasions and amoxycillin on six. synergy, which might have clinical relevance, was demonstrated only when the ... | 1979 | 227829 |
| mutant single-strand binding protein of escherichia coli: genetic and physiological characterization. | a mutation in the escherichia coli gene for single-strand binding protein results in temperature-sensitive deoxyribonucleic acid replication (r. r. meyer, j. glassberg, and a. kornberg, proc. natl. acad. sci. u.s.a. 76:1702-1705, 1979). the mutant (ssb-1) is also more sensitive to ultraviolet irradiation and about one-fifth as active in recombination. single-strand binding protein is thus implicated in repair and recombination as well as in replication. the mutation in ssb is located between uvr ... | 1979 | 227832 |
| deoxyribonucleic acid and outer membrane: binding to outer membrane involves a specific protein. | the binding of deoxyribonucleic acid (dna) to the outer membrane of escherichia coli was examined. the amount of dna found to be bound to outer membrane was low and was estimated to be about 0.4% of the total dna. treatment of cells with chloramphenicol or rifampin caused a disassociation of the apparent dna-outer membrane complex. the results presented here suggest that the binding between membrane and dna is specific and involves a membrane protein having a molecular weight of 13,000. | 1979 | 227834 |
| deoxyribonucleic acid and outer membrane: strains diploid for the oric region show elevated levels of deoxyribonucleic acid-binding protein and evidence for specific binding of the oric region to outer membrane. | we have recently reported that part of the chromosomal deoxyribonucleic acid (dna) of escherichia coli is associated with the outer membrane fraction and that an outer membrane protein having a molecular weight of 31,000 probably is involved in this association (h. wolf-watz and a. norqvist, j. bacteriol. 140:43-49, 1979). we have now found that f' merodiploid strains containing two copies of the dna between bglb and ilv have increased levels of this protein and an increased amount of dna in the ... | 1979 | 227835 |
| a new gene of escherichia coli k-12 whose product participates in t4 bacteriophage late gene expression: interaction of lit with the t4-induced polynucleotide 5'-kinase 3'-phosphatase. | we isolated five escherichia coli mutants deficient in their ability to support the late (replication-coupled) gene expression of t4 bacteriophage at 30 degrees c. these mutants, which we call lit mutants, define at least one novel gene at 25 min on the e. coli map. they were selected in an attempt to obtain mutants which restrict the growth of t4 mutants deficient in polynucleotide 5'-kinase 3'-phosphatase but not that of wild-type t4 at 37 degrees c. some of the mutants do have these phenotype ... | 1979 | 227837 |
| cyclic adenosine 3',5'-monophosphate regulation of the bacteriophage t6/colicin k receptor in escherichia coli. | mutant strains of escherichia coli unable to synthesize cyclic adenosine 3',5'-monophosphate (camp) or the cyclic adenosine monophosphate receptor protein (crp) were more resistant than wild-type cells to infection by bacteriophage t6. this resistance was found to be associated with the decreased production of specific t6 receptor protein (also the colicin k receptor) located in the outer membrane protein fraction of these cells. transcription of this particular outer membrane protein was regula ... | 1979 | 227838 |
| production and excretion of cloacin df13 by escherichia coli harboring plasmid clodf13. | the production and the mechanism of excretion of cloacin df13 were investigated in noninduced and mitomycin c-induced cell cultures. a mitomycin c concentration was selected which did not cause lysis of cloacinogenic cells, but at the same time induced a maximal production of cloacin df13. native cloacin df13, possessing killing activity, was first released into the cytoplasm. shortly thereafter, the bacteriocin was transported through the cytoplasmic membrane and accumulated in the periplasm. f ... | 1979 | 227839 |
| escherichia coli mutants thermosensitive for deoxyribonucleic acid gyrase subunit a: effects on deoxyribonucleic acid replication, transcription, and bacteriophage growth. | temperature-sensitive nala mutants of escherichia coli have been used to investigate the structure and functions of deoxyribonucleic acid (dna) gyrase. extracts of one such mutant (nala43) had thermosensitive dna gyrase subunit a activity but normal gyrase subunit b activity, proving definitively that nala is the structural gene for subunit a. extracts of a second nala (ts) mutant (nala45) had a 50-fold deficiency of gyrase subunit a activity. the residual dna supertwisting was catalyzed by the ... | 1979 | 227840 |
| transport of cyclic adenosine 3',5'-monophosphate across escherichia coli vesicle membranes. | the uptake and efflux of cyclic adenosine 3',5'-monophosphate (3',5'-camp) by escherichia coli membrane vesicles were studied. metabolic energy was not required for the uptake process and was found to actually decrease the amount of 3',5'-camp found in the vesicles. 3',5'-camp uptake exhibits saturation kinetics (km = 10 mm, vmax = 2.8 nmol/mg of protein per min) and was competitively inhibited by a number of 3',5'-camp analogs. the uptake of 3',5'-camp was found to be sharply affected by a memb ... | 1979 | 227841 |
| paraquat and escherichia coli. mechanism of production of extracellular superoxide radical. | paraquat mediates a superoxide dismutase-inhibitable reduction of cytochrome c by suspensions of escherichia coli b. glucose was most effective in providing electrons for this cytochrome c reduction, but other nutrients could serve in this capacity, provided the cells were preconditioned by growth on these nutrients. paraquat reduction depended upon a nadph:paraquat diaphorase, present in the cytosol. reduced paraquat could diffuse across the cell envelope and react with dioxygen, in the suspend ... | 1979 | 227855 |
| interaction between dna and escherichia coli dna topoisomerase i. formation of complexes between the protein and superhelical and nonsuperhelical duplex dnas. | | 1979 | 227859 |
| search for a dna gyrase in mammalian mitochondria. | incorporation of labeled deoxynucleoside triphosphates into mtdna by isolated rat liver mitochondria has been shown previously to reflect dna replication. we have used this system to seek evidence for a mtdna gyrase. coumermycin, novobiocin, nalidixic acid, and oxolinic acid are known to be inhibitors of escherichia coli gyrase, to inhibit e. coli dna replication, to abolish colicin e1 replication, and to depress the supercoiling of phage lambda dna, the last two via inhibition of the dna gyrase ... | 1979 | 227861 |
| metabolism of okazaki fragments during simian virus 40 dna replication. | essentially all of the okazaki fragments on replicating simian virus 40 (sv40)dna could be grouped into one of three classes. class i okazaki fragments (about 20%) were separated from longer nascent dna chains by a single phosphodiester bond interruption (nick) and were quantitatively identified by treating purified replicating dna with escherichia coli dna ligase and then measuring the fraction of okazaki fragments joined to longer nascent dna chains. similarly, class ii okazaki fragments (abou ... | 1979 | 227871 |
| deoxyribonucleic acid polymerase of bacteriophage t7. characterization of the exonuclease activities of the gene 5 protein and the reconstituted polymerase. | homogeneous gene 5 protein of bacteriophage t7, a subunit of t7 dna polymerase, catalyzes the stepwise hydrolysis of single-stranded dna in a 3' leads to 5' direction to yield nucleoside 5'-monophosphates. the gene 5 protein itself does not hydrolyze duplex dna. however, in the presence of escherichia coli thioredoxin, the host-specified subunit of t7 dna polymerase, duplex dna is hydrolyzed in a 3' leads to 5' direction to yield nucleoside 5'-monophosphates. the apparent km for thioredoxin in t ... | 1979 | 227873 |
| enzyme-catalyzed dna unwinding. a dna-dependent atpase from e. coli. | we have isolated a new dna-dependent atpase from e. coli. the enzyme has been purified to greater than 90% purity. it appears to be composed of two identical polypeptide chains of molecular weight 20,000. the enzyme catalyzed the hydrolysis of atp in the presence, but not in the absence, of single-stranded dna. double-stranded dna is not a cofactor. the products of hydrolysis are adp and pi. the enzyme also catalyzed strand separation of duplex dna in the presence of atp and e. coli dna binding ... | 1979 | 227886 |
| spectroscopic techniques for study of phosphodiester bond formation by escherichia coli rna polymerase. | nucleotides containing the fluorophore 1-aminonaphthalene-5-sulfonate attached to the gamma phosphoryl group via a phosphoamidate bond are excellent substrates for escherichia coli dna-dependent rna polymerase. cleavage of the alpha-beta-phosphoryl bond produces significant changes in both absorption and fluorescence spectra. these alterations provide a sensitive and precise means for continuous monitoring of transcription. under appropriate conditions one can detect the utilization of less than ... | 1979 | 227888 |
| a new system for studying molecular mechanisms of mutation by carcinogens. | a new system for studying the molecular mechanisms of mutation by carcinogens is described. the system involves (a) site-specific modification of the essential gene g in phi x174 replicative form dna by a combination of chemical and enzymatic steps; (b) production of mutant virus carrying a change at a single preselected site by transfection of spheroplasts with the site modified phi x174 dna; (c) detection and propagation of mutants using a host carrying the plasmid, p phi xg, that rescues all ... | 1979 | 227905 |
| neutralization of human serum beta-lysin by sodium polyanetholsulfonate and sodium amylosulfate. | normal fresh and heat-inactivated (56 degrees c, 30 min) human sera (80 vol%, i.e., 80% [vol/vol] of a 2-ml assay volume) killed bacillus subtilis atcc 6633 cell inocula of 1.5 x 10(4) colony-forming units per ml within 1 to 2 h after exposure. the b. subtilis assay strain proved slightly and reversibly susceptible to 5 mug of egg white lysozyme per ml. seitz filtration of fresh human serum completely removed beta-lysin activity; significant amounts of serum lysozyme were removed as well, as det ... | 1979 | 227918 |
| variable neutralization of several nonspecific antibacterial systems in fresh, defibrinated human blood by sodium polyanetholsulfonate and sodium amylosulfate. | fresh, defibrinated human blood (80 vol%, i.e., 80% [vol/vol] of a 2-ml final assay volume) from two healthy adult donors killed "delayed serum-sensitive" (dss) and "promptly serum-sensitive" (pss) strains of serratia marcescens, pss control strain escherichia coli c, bacillus subtilis strain atcc 6633, and micrococcus lysodeikticus atcc 4698 in a kinetic manner comparable to that of fresh human serum (80 vol%). however, heat-inactivated (56 degrees c, 30 min), defibrinated human blood revealed ... | 1979 | 227919 |
| new function for high density lipoproteins. their participation in intravascular reactions of bacterial lipopolysaccharides. | the addition of bacterial lipopolysaccharide (lps) from escherichia coli 0111:b4 or salmonella minnesota r595 to plasma (or serum) resulted in a marked reduction of the hydrated buoyant density of the parent lps (0111:b4 [d = 1.44 g/cm3] and r595 [d = 1.38 g/cm3]), to d less than 1.2 g/cm3. this reduction in buoyant density to less than 1.2 g/cm3 of the lps required plasma (or serum) lipid. delipidation of plasma (or serum) by extraction with n-butanol/diisopropyl ether (40/60, vol:vol) prevente ... | 1979 | 227936 |
| hybrid plasmids containing an active thymidine kinase gene of herpes simplex virus 1. | the gene for the thymidine kinase (tk) of herpes simplex virus type 1 (hsv-1) is located in the kpni m and bamhi p fragments of the genome (wigler et al., cell 11, 223-232 (1977)). these fragments have been inserted into the ecori and bamhi sites, respectively, of plasmid pbr322, and propagated in e.coli. the tk gene contained in the recombinant plasmids was shown to be biologically active when introduced into tk- mouse l cells. detailed restriction site maps of the bamhi p fragment have been co ... | 1979 | 228250 |
| non-specific interactions of crp from e. coli with native and denatured dnas: control of binding by camp and cgmp and by cation concentration. | the cyclic adenosine 3',5'-monophosphate receptor protein of escherichia coli (crp) binds cooperatively to single- and double-stranded dna. binding data could be fitted to the model of mcghee and von hippel (1) and show that neither strandedness of dna, nor the effectors camp and cgmp or the ionic strength (kcl) do change appreciably the cooperativity parameter omega (omega approximately or equal to 100), and site size of dna. instead, distinctly different slopes were observed for the linear dec ... | 1979 | 228253 |
| escherichia coli heat-labile enterotoxin: dna-directed in vitro synthesis and structure. | escherichia coli heat-labile enterotoxin was synthesized in a cell-free system directed by dna of the plasmid p307. synthesis of the toxin, assayed by the elongation induced in chinese hamster ovary cells, was strongly stimulated by cyclic amp and occurred at physiological levels of mg2+ only when the polyamine spermidine was present. activity was abolished by heat and antisera prepared against the enterotoxins of both e. coli p263 and vibrio cholera. tritium-labeled enterotoxin was purified by ... | 1979 | 228267 |
| interaction site of escherichia coli cyclic amp receptor protein on dna of galactose operon promoters. | cyclic amp (camp) and its receptor protein (crp) have a dual role in the regulation of the two promoters that control the galactose (gal) operon of escherichia coli. one promoter, p1, requires camp-crp for activity; the other, p2, is inhibited by these factors. we have examined the interactions site of camp-crp on gal dna by using two types of protection experiments, involving dnase digestion and methylation by dimethyl sulfate. our results indicate that camp-crp binds to gal dna in a segment lo ... | 1979 | 228278 |