Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Attempts to prevent the urea conversion of a 200-230,000 molecular weight DNA polymerase alpha to a 150-170,000 molecular weight form by the inclusion of protease inhibitors have not been successful. No other method has been found capable of dissociating a 50-70,000 fragment or subunit from the DNA polymerase subunit. Addition of this 50-70,000 subunit to the polymerase subunit does not aid the binding of the enzyme to DNA, but does have an effect on the utilisation of synthetic template-initiator complexes by the polymerase subunit.
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PMID:Further studies on partially purified calf thymus DNA polymerase a. 48 29

The relationship between two DNA polymerase alpha species from mammalian tissues has been resolved with the isolation of a protease from rat thymus which converts the larger alpha polymerase (7.3S) to a smaller (5.4S) size. The proteolytic activity is present only in the chromatin fraction and the limited proteolysis is accompanied by an increase in activity of the DNA polymerase, possibly consistent with a biological control function for this phenomenon.
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PMID:Proteolytic conversion of rat thymus DNA polymerase alpha to a more active form. 48 42

A regulatory protein for DNA polymerase alpha, responsive to noncomplementary deoxyribonucleoside triphosphates, has been isolated from calf thymus. The regulatory protein was separated from DNA polymerase alpha using Affi-Gel Blue and gel filtration. The regulatory protein had a molecular weight of approximately 70,000 as determined by gel filtration, and its activity was nondialyzable, heat labile, and abolished by pronase treatment. In the presence of regulatory protein, DNA polymerase alpha activity, measured by using polydeoxyadenylate-oligodeoxythymidylate as template primer, was inhibited by 2'-deoxyguanosine 5'-triphosphate in a parabolic-competitive fashion [Ki = 15 +/- 1 (S.E.) microM] and by 2'-deoxycytidine 5'-triphosphate in a linear-competitive manner (Ki = 162 +/- 23 microM). Neither the four natural ribonucleoside triphosphates nor 2'-deoxyadenosine 5'-triphosphate inhibited the DNA polymerase-regulatory protein system to any significant extent. The regulatory protein by itself had no effect on either DNA polymerase alpha activity or the Km for template primer. These results indicate that deoxyribonucleoside triphosphate pools may be involved in the regulation of cellular DNA synthesis through a direct effect on DNA polymerization.
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PMID:Isolation of a DNA polymerase alpha-associated regulatory protein from calf thymus. 49 66

The activities of DNA polymerases alpha, beta, and gamma and of thymidine kinase were determined in the chick neural retina at different stages of embryonic development (starting at seven days) and after hatching (up to five years). Crude extracts of neural retinae were fractionated by centrifugation on sucrose gradients and the enzymatic activities measured using specific assays. The DNA polymerase alpha activity decreases greatly between 7 and 11 days of incubation. This decrease parallels the decline in mitotic activity. However, a constant residual activity remains after hatching, even in the oldest animals. DNA polymerase beta activity increases slightly between 7 and 14 days of incubation; it then decreases slowly until seven days after hatching and remains constant thereafter. DNA polymerase gamma activity is maximal between 7 and 14 days of incubation and then decreases until hatching. The activity of thymidine kinase increases slightly during the embryonic life until hatching and remains almost constant thereafter. The implication of these enzymes in DNA replication and repair processes is discussed.
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PMID:Variation of DNA polymerase activities in chick neural retina as a function of age. 52 76

It has often been suggested that the high molecular weight DNA polymerase alpha of eukaryotes plays a role in de novo replication of DNA, while the low molecular weight polymerase beta is involved in repair replication. Previous studies have shown that when diethylnitrosamine is fed in the diet to rats it causes after a few weeks an increase in de novo replication of DNA, which then returns to normal values. In contrast, repair replication may be expected to continue throughout the feeding period. Study of DNA polymerase activity in livers of animals during carcinogenesis showed that an increase in polymerase alpha occurred at the time of increased de novo replication, while there was a gradual increase in polymerase beta during the time diethylnitrosamine was present in the diet. When diethylnitrosamine treatment was stopped, there was a rapid drop in polymerase beta activity. These results support the view that the polymerase alpha is involved in DNA replication, that the polymerase beta functions in repair replication, and that the beta enzyme can be induced by chronic damage to DNA.
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PMID:Sequential changes in DNA polymerases alpha and beta during diethylnitrosamine-induced carcinogenesis. 53 37

RNA polymerase B and DNA polymerase alpha were highly enriched simultaneously from calf thymus. It was shown that the preparation exhibits RNA-synthesizing activity, which is able to stimulate in vitro DNA synthesis by DNA polymerase alpha by its preceding RNA synthesis. A part of the DNA was found to be covalently attached to RNA in Cs2SO4 equilibrium gradients after denaturation by formamide.
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PMID:RNA-primed DNA synthesis by an enzyme preparation of calf thymus containing highly enriched RNA polymerase B and DNA polymerase. 54 71

Two forms of DNA polymerase alpha were separated from HeLa cells by DEAE-cellulose column chromatography and affinity chromatography using a DNA-cellulose column. They were eluted from a DEAE-cellulose column at 0.22M KCl (P-I) and 0.24M KCl (P-II). Upon cell fractionation between cytosol and nuclei, P-I was recovered from nuclei and P-II from cytosol. P-I was found to have a higher binding affinity to DNA than P-II by DNA-cellulose column chromatography.
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PMID:Separation of two forms of HeLa DNA polymerase alpha with different binding affinity to DNA. 55 47

More than half of the DNA polymerase beta in mouse ascites cell chromatin was found to be associated with monomeric nucleosomal particles (produced by micrococcal nuclease treatment of chromatin). Almost all nuclear DNA polymerase activity in lymphocytes was found to be associated with nucleosomes. The nucleosome-associated enzyme was mainly DNA polymerase beta in chromatin from resting and mainly DNA polymerase alpha in chromatin from concanavalin-A-stimulated lymphocytes.
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PMID:Association of DNA polymerase with nucleosomes from mammalian cell chromatin. 56 14

DNA polymerase was purified 1000-fold from the cytoplasm of microplasmodia of the myxomycete Physarum polycephalum. The activity was found in two forms exhibiting molecular weights of 204000 and 116000 respectively. Both forms eluted together from DNA-cellulose and DEAE-Sephadex columns. The Stokes radii were 6.5 and 5.5 nm. The sedimentation coefficients were 7.6 and 5.2 S. The frictional ratios of 1.69 suggest a highly hydrated and/or an asymmetric structure of the molecule. The enzyme-catalyzed reaction was sensitive to N-ethylmaleimide (60% inhibition by 1 mM). Unlike DNA polymerase alpha from mammalian cells the Physarum enzyme was stimulated by 30 mM NaCl. Activated DNA was the preferred template. Poly(A) . (DT)12 was not accepted. The Km value for deoxynucleoside triphosphates was 3 micron, for activated DNA 50 microgram/ml and for Mg2+ at the optimum [k+] of 150 mM about 0.6 mM.
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PMID:Deoxyribonucleic acid polymerase from Physarum polycephalum. Properties of the major cytoplasmic activity in exponentially growing microplasmodia. 56 99

This is the first report dealing with the effect of 1-beta-D-arabinofuranosylthymine 5'-triphosphate (araTTP), synthesized by a new method, on eukaryotic DNA polymerase [EC 2.7.7.7]. AraTTP was tested for the inhibition of DNA synthesis in vitro using highly purified mouse myeloma DNA polymerase alpha in comparison with 1-beta-D-arabinofuranosylcytosine 5'-triphosphate (araCTP). AraTTP was found to inhibit competitively the incorporation of [3H]dTTP into DNA and non-competitively the incorporation of [3H]dCTP, while the mode of the inhibition by araCTP was non-competitive with respect to dTTP and competitive with respect to dCTP. Neither araTTP nor araCTP was utilized as a substrate in place of dTTP or dCTP in DNA synthesis by DNA polymerase alpha.
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PMID:Inhibition of mouse myeloma DNA polymerase alpha by 5-triphosphates of 1-beta-D-arabinofuranosylthymine and 1-beta-D-arabinofuranosylcytosine. 56 67


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