共查询到20条相似文献,搜索用时 31 毫秒
1.
George Boguslawski William S. Oetting Dean A. Stetler 《Biochemical and biophysical research communications》1977,78(2):684-689
An enzyme, ribonucleotide polymerase, isolated from the yeast phase of a fungus, has been found to stimulate the incorporation of dTMP in the reaction catalysed by DNA polymerase from and . The stimulation is dependent on the amount of ribonucleotide polymerase added. The data indicate that protein-protein interaction is responsible for the increase in DNA synthesis. It is suggested that ribonucleotide polymerase may be involved in supplying short RNA primers for DNA polymerase. 相似文献
2.
W.D.W. Heston Barry R. Zirkin Donald S. Coffey 《Biochemical and biophysical research communications》1975,64(1):162-168
The addition of the acidic polymers heparin or polyxanthylic acid to rabbit spermatozoa or sperm heads previously exposed to disulfide reducing agents released sperm DNA template restriction and stimulated high levels of incorporation of DNA precursor into DNA, as assayed with exogenous DNA polymerase. Incorporation did not occur in the presence of DNAase, or in the absence of magnesium ion, any of the four deoxyribonucleotides, or DNA polymerase. This represents the first report that spermatozoa can synthesize DNA . 相似文献
3.
Neomycin inhibits DNA dependent DNA and RNA synthesis catalyzed by DNA polymerase I and RNA polymerase from . The effect of the antibiotic is more pronounced towards DNA synthesis. The inhibition of DNA synthesis is competitive with template DNA, does not reverse with excess deoxynucleoside triphosphate, Mg2+ or enzyme DNA polymerase I. Neomycin does not reduce the number of potential 3′ -OH end or primer. It seems to shorten the size of the newly formed polynucleotide. 相似文献
4.
Excision of thymine dimers by proteolytic and amber fragments of E. coli DNA polymerase I 总被引:11,自引:0,他引:11
Excision of thymine dimers from specifically incised ultraviolet irradiated DNA by DNA polymerase I is stimulated by concurrent DNA synthesis. The 36,000 molecular-weight “small fragment” obtained by limited proteolysis of DNA polymerase I, which retains only the 5′ → 3′ exonuclease activity, also excises thymine dimers, but at one-tenth the rate of the intact enzyme. However, the rate of excision is increased by addition of the “large” 76,000-molecular weight fragment. With the further addition of the 4 deoxynucleoside triphosphates, permitting DNA synthesis to occur, excision approaches rates observed with the intact enzyme. The same result was obtained with a fragment of DNA polymerase I with 5′ → 3′ exonuclease activity that is present uniquely in polymerase I mutants. 相似文献
5.
Template specificity changes of DNA-dependent RNA polymerase in B. subtilis during sporulation 总被引:4,自引:0,他引:4
Previous work has indicated that loss of ability of DNA dependent RNA polymerase, from stationary phase cultures of , to transcribe phage øe DNA was a for sporulation. To ascertain if this change in template specificity was sporulation-specific, we repeated these experiments using a defined sporulation medium. The changes observed previously did not occur in the defined medium although sporulation was normal. The ability of the enzyme to transcribe other DNA templates was also examined. Similar studies were carried out using a polymerase from a rifamycin-resistant, sporulation conditional mutant. The significance of these findings with regard to the regulation of sporulation in is discussed. 相似文献
6.
P Robertson K A Koehler R G Hiskey 《Biochemical and biophysical research communications》1979,86(2):265-270
The binding of magnesium ions to two tripeptides, -Arg--Gla--Gla-OMe and Z--Arg(NO2)--Gla--Gla-OMe, and to bovine prothrombin fragment 1 as a function of pH has been monitored by 25Mg NMR spectroscopy. Binding to the tripeptide was dependent on peptide ionizations occurring at pH 4.6 – 4.8. The pH dependence of magnesium ion binding to fragment 1 reveals two inflection points 4.2 may be attributed to the deprotonation of the third side chain carboxylic acid group of the double γ-carboxyglutamic acid sequence. The origin of the increased binding of magnesium ions to fragment 1 at pH values above 7 is unknown. 相似文献
7.
The effect of ionising radiation and chemical methylation upon the activity and accuracy of E. COLI DNA polymerase I 总被引:1,自引:0,他引:1
R Saffhill 《Biochemical and biophysical research communications》1974,61(2):802-808
The activity of DNA polymerase I decreases on treatment with γ-rays, methylnitrosourea or dimethyl sulphate. In the case of the first two agents the decrease in activity is accompanied by a decrease in the accuracy of the enzyme in an assay. There is no detectable change in the ratio of DNA polymerase activity to 3′→5′ exonuclease activity on treatment. 相似文献
8.
Paul Petranyl Jerome J. Jendrisak Richard R. Burgess 《Biochemical and biophysical research communications》1977,74(3):1031-1038
Atomic absorption studies indicate that the DNA-dependent RNA polymerase II from wheat germ contains about 7 tightly bound zinc atoms per enzyme molecule. This value has been repeatedly obtained with a number of enzyme preparations subjected to varying conditions of purification and dialysis. However, prolonged dialysis of the enzyme with the metal chelator -phenanthroline results in the loss of enzyme activity and extraction of the bound zinc. Other metals including copper, cobalt, manganese, magnesium, chromium, nickel and iron were not present in significant amounts. 相似文献
9.
Novobiocin and nalidixic acid target proteins in yeast 总被引:3,自引:0,他引:3
Novobiocin (and its related drug, coumermycin A1) and nalidixic acid are specific inhibitors of DNA gyrase in bacteria. These drugs inhibit many enzymatic activities in yeast; such as DNA polymerase activity in crude extracts, 2-μm plasmid DNA replication, purified DNA polymerase I and II, and topoisomerase I. Therefore, the inhibition by these inhibitors in yeast is not specific for a particular enzyme. 相似文献
10.
Mutational alteration of Bacillus subtilis DNA polymerase 3 to hydroxyphenylazopyrimidine resistance: polymerase 3 is necessary for DNA replication 总被引:18,自引:0,他引:18
A spontaneous mutant of resistant to killing by two hydroxyphenylazopyrimidines has been isolated. The DNA polymerase III of this mutant is resistant to inhibition by these drugs. The Ki for 6-(p-hydroxyphenylazo)-uracil (HPUra) is 20 μM, about 40 times higher than the Ki of the wild-type enzyme. The mutant and wild-type polymerases behave similarly during purification, are sensitive to N-ethylmaleimide and to 0.1 M KCl, and have the same Km for dGTP (0.5 μM). The HPUra inhibition of both enzymes is attenuated competitively by dGTP. We conclude that polymerase III is the target for hydroxyphenylazopyrimidines , and since the drugs specifically inhibit replicative DNA synthesis, polymerase III is necessary for DNA replication. 相似文献
11.
S G Bhat M Ramanarayanan C S Vaidyanathan 《Biochemical and biophysical research communications》1973,52(3):834-842
A soluble fraction of catalyzed the hydroxylation of mandelic acid to -hydroxymandelic acid. The enzyme had a pH optimum of 5.4 and showed an absolute requirement for Fe2+, tetrahydropteridine, NADPH. -Hydroxymandelate, the product of the enzyme reaction was identified by paper chromatography, thin layer chromatography, UV and IR-spectra. 相似文献
12.
Effect of aphidicolin on viral and human DNA polymerases. 总被引:9,自引:0,他引:9
DNA polymerases induced by Herpes simplex and Vaccinia viruses are inhibited by aphidicolin and this inhibition is probably the basis of its antiviral activity . Its possible clinical use is however hampered by the concomitant effect on human replicative DNA polymerase α. The inhibition of human α-polymerase is reversible both and and the changes in the rate of incorporation of thymidine into DNA, following treatment with aphidicolin for a generation time, indicate the likely synchronization of the cells due to this agent. DNA polymerase β, which has recently been shown to carry out repair synthesis of damaged nuclear DNA, is not inhibited by aphidicolin either on suggesting that the drug could allow a rapid and simple evaluation of DNA repair synthesis due to DNA polymerase β. 相似文献
13.
Wolfgang Feller Hartmut Follmann 《Biochemical and biophysical research communications》1976,70(3):752-758
A ribonucleoside diphosphate reductase is demonstrated in the algae, and . In synchronized cultures an activity maximum at the 12th hour of the cell cycle coincides with maximum DNA production. Induction of reductase activity is prevented by cycloheximide. The enzyme requires dithiols for reduction of CDP ; it is not significantly stimulated by iron or magnesium ions nor dependent upon deoxyadenosylcobalamin. ATP stimulates the reaction but dATP or dTTP act as inhibitors. The ribonucleotide reductase of green algae differs from the B12-requiring enzyme characterized in . 相似文献
14.
K H Falchuk L Ulpino B Mazus B L Vallee 《Biochemical and biophysical research communications》1977,74(3):1206-1212
DNA dependent RNA polymerase I has been purified to homogeneity. α-amanitin, over the concentration range 0.05 to 200 μg/ml, does not affect its activity, consistent with its being classified as an RNA polymerase I. Based on a molecular weight of 624,000 daltons the enzyme contains 2.2 g atom of Zn but no Mn, Cu, Fe, as determined by microwave excitation emission spectrometry. Zinc is essential for activity since the chelating agent, 1,10-phenanthroline, inhibits enzymatic function but its non-chelating analogue, 4,7-phenanthroline is ineffective. Thus, like the RNA polymerase II, zinc is a catalytically essential component of RNA polymerase I (1). 相似文献
15.
Stuart L. Marcus Gregg Lipschik Generosa Trueba Cyrus J. Bacchi 《Biochemical and biophysical research communications》1980,93(4):1027-1035
A single peak of DNA polymerase activity from extracts of , obtained by DEAE-cellulose and phosphocellulose ion-exchange chromatography, was resolved into two peaks differing in KCl concentration necessary to elute them from a DNA-agarose column. Peak I (eluting at 0.2 M KCl) and Peak II (eluting at 0.4 M KCl), differed in response to increasing KCl concentrations, although both functioned optimally with Mg2+ as divalent cation when DNA synthesis was directed either by activated DNA or poly (dC)·(dG)12–18. Due to the potential significance of polyamines in the metabolism of , the effect of exogenous polyamine on rates of DNA synthesis by the peak I and II enzymes was compared with that of murine DNA polymerase alpha. Only the peak I enzyme was significantly stimulated (up to 4-fold) by the biologically active polyamines spermine and spermidine at physiological concentrations. The response of the peak I enzyme resembled that of the alpha polymerase. This result suggests a possible functional difference between peak I and II enzymes, as well as a potential target site for trypanocidal drug development. 相似文献
16.
C T Hadden 《Biochemical and biophysical research communications》1973,51(3):501-506
The effect of a deficiency in DNA polymerase on recombination in has been studied. It is concluded that the major DNA polymerase of is not required for recombination, and that the recombination deficiency of a previously described DNA polymerase-deficient mutant is actually due to a mutation. Genetic crosses imply that this recombination deficiency is not or . 相似文献
17.
The pyridine nucleotide cycle: presence of a nicotinamide mononucleotide-specific amidohydrolase in Propionibacterium shermanii 总被引:2,自引:0,他引:2
A specific nicotinamide mononucleotide amidohydrolase which catalyzes the stoichiometric conversion of NMN to nicotinate mononucleotide and ammonia has been partially purified from an extract of . The reaction has optimum activity at pH 5.6, a Km of 70 μM, and an experimental activation energy of 14.5 Kcal/mole. The enzyme appears to be highly specific for NMN. Neither free nicotinamide nor NAD, NADH, NADP, NADPH compete with NMN. Numerous substances such as isonicotinic acid hydrazide and quinolinic acid are also without effect. It can be stored at ?15° in 12% glycerol, but is somewhat unstable in the absence of this solvent. The enzyme is composed of a heatstable and a heat-sensitive subunit. This enzyme considerably simplifies the pyridine nucleotide cycle, and may, besides this salvage function for NAD, play a role in B12 biosynthesis and in the bacterial DNA ligase reaction. 相似文献
18.
19.
Covalent binding of proteins and glucose-6-phosphate dehydrogenase to cellulosic carriers activated with s-triazine trichloride 总被引:2,自引:0,他引:2
A method was developed for covalently binding proteins and enzymes to cellulosic carriers such that the enzymes retained high specific activity. Optimal conditions for activating the carriers with s-triazine trichloride were found to be: (a) pretreatment of cellulose with 3 m NaOH; and (b) reaction with 5% () s-triazine trichloride in dioxane-xylene (1:1 ) for 30 min at room temperature. All proteins tested bound most readily at pH values below pH 7. Extensive investigation of immobilized glucose-6-phosphate dehydrogenase showed that: (a) over 80% of the specific activity of the enzyme was retained; and (b) the pH optimum and Km values were not altered significantly from that of the free enzyme. The binding method has been applied successfully to hexokinase, phosphorylase and pronase. 相似文献
20.
G Goldberg T Zarucki-Schulz P Caldwell H Weissbach N Brot 《Biochemical and biophysical research communications》1979,91(4):1453-1461
The DNA dependent synthesis of ribosomal protein L12 and the β subunit of RNA polymerase has been investigated using DNA from a plasmid which contains the genetic information for ribosomal protein L12 and the β subunit of RNA polymerase. This DNA, however, lacks the promoter region and the genetic information for the first 26 amino acids of ribosomal protein L10. It was found that L12 and the β subunit of RNA polymerase are efficiently synthesized from this DNA. These results suggest that L12 and the β subunit of RNA polymerase can be synthesized from a promoter situated within the L10 gene. 相似文献