Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The experimental conditions were studied which allow hormonal levels to affect the incorporation of labelled deoxyribonucleosides triphosphates (dNTP's) into mitochondrial DNA by isolated liver mitochondria, obtained either from thyroidectomized young male rats (T) or from animals of the same age thyroidectomized and then treated with triiodothyronine (T + T3). It was demonstrated that: (a) extramitochondrial DNA, on which extramitochondrial DNA polymerase may act, was absent; (b) the permeability to dNTP's, the thymidine kinase activity, the energy supply, and the nuclease activities were unaffected by hormonal conditions; (c) the bacterial contaminations contribute for only 1% to incorporation. The characterization of incorporation product showed that: (a) such product was indeed DNA, as it was DNase-degradable for about 90%; (b) the labelled DNA was indeed mitochondrial DNA, as a 10 minutes preincubation with acriflavine or ethydium bromide (Eth. Br.) inhibited the synthesis by 90%.
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PMID:Effect of thyroidectomy and in vivo administration of triiodothyronine on DNA synthesis in isolated mitochondria. 18 48

Incubation of HeLa cells with the anticancer agent N-methyl-N-nitrosourea (MNU) results in: (a) depression of intracellular nicotinamide adenine dinucleotide levels; (b) stimulation of the chromatin-associated, chromosomal protein-modifying enzyme polyadenosine diphosphoribose [poly(ADP-ribose)] polymerase, which uses nicotinamide adenine dinucleotide as substrate; and (c) some fragmentation of cellular DNA. DNase treatment of HeLa nuclei in vitro also stimulates poly(ADP-ribose) polymerase activity, but not in nuclei derived from MNU-treated cells unless they have been subsequently incubated to allow for recovery from MNU damage. DNA polymerase activity is stimulated in vitro by poly(ADP) ribosylation of nuclear proteins. By using intact nuclei derived from MNU-treated HeLa cells, the repair via elongation of single-strand DNA breaks is demonstrated in vitro. This repair is dependent on DNA polymerase activity and is enhanced by adenosine diphosphate ribosylation of histones. Inhibition of poly(ADP-ribose) polymerase with nicotinamide results in extensive degradation of MNU-damaged DNA. Taken as a whole, these results suggest that poly(ADP-ribose) polymerase may play a role in the repair of alkylation damage to cellular DNA and that the inhibition of this enzyme in vivo might be exploited to potentiate the antitumor and carcinogenic activities of MNU.
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PMID:A putative role for nicotinamide adenine dinucleotide-promoted nuclear protein modification in the antitumor activity of N-methyl-N-nitrosourea. 19 15

A DNA-unwinding protein has been purified from regenerating rat liver cytosol to apparent homogeneity. The protein is present in about 10(6) copies per cell. It is a tetramer, composed of 25,000-dalton subunits which does not exhibit enzymatic activity for ATPase, DNA polymerase, or DNase. The protein is able to unwind the double helix of poly[d(A-T)], depressing the melting point of this synthetic polymer by about 40 degrees. It also binds to supercoiled SV40 DNA, probably by melting A-T-rich regions in the genome. The fully saturated complex of protein and SV40 DNA sediments at 30 S. Homologous DNA polymerases-alpha and -beta are stimulated by the protein at a different level depending on the templates used. This result argues in favor of the intervention of the unwinding protein in replication processes.
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PMID:A deoxyribonucleic acid unwinding protein isolated from regenerating rat liver. Physical and functional properties. 20 98

During the productive infection of KB cells by adenovirus type 5 (Ad5), there is a progressive decrease in the level of cellular DNase activity towards single-stranded DNA, in contrast to DNA polymerase which remains relatively constant throughout the infection. This decrease is prevented by the inhibition of protein synthesis by cycloheximide. The inhibition of DNase activity does not occur after infection by Ad5 ts125, a DNA-negative mutant which fails to induce the adenovirus-specific DNA binding protein. In contrast, infection by Ad5 ts36, a DNA-negative mutant which complements ts125, does result in decreased levels of DNase. A mechanism is discussed in which the DNA binding protein protects viral replicative intermediates from degradation by cellular DNase.
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PMID:Adenovirus-induced inhibition of cellular DNase. 20 1

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), respectively. The in vitro system used was capable of synthesizing double-stranded DNA, but the plus strands (same polarity as the viral RNA) were only 0.5 to 1.5 kb long. Lone Moloney murine leukemia virus cDNA transcripts were used as templates to synthesize the second plus strand. Essentially two strategies were employed as follows. (i) The 3' ends of the cDNA transcripts were extended by addition of 50 to 100 dAMP residues by terminal deoxynucleotidyl transferase. The (dA)n-tailed cDNA transcripts were used as templates along with an oligomer of dT as primer and Escherichia coli DNA polymerase to synthesize the plus strands. (ii) DNase-digested calf thymus DNA was used to prime the synthesis of plus strands on long cDNA with E. coli DNA polymerase I. In both cases, the synthesis of the plus strands was monitored by increased resistance of the cDNA templates to single-strand-specific S1 nuclease. The double-stranded DNA was fractionated on neutral sucrose gradients. Analysis of the double-stranded DNA synthesized by using oligo(dT) primer showed the plus strands to be about 5 to 6 kb long, whereas the plus strands synthesized by using DNase-digested calf thymus DNA primers were only 0.3 to 0.5 kb long. Double-stranded DNA synthesized by either method has an average size of 6 x 10(6) daltons. Double-stranded DNA was also synthesized by using cDNA transcripts as templates without the addition of any primers. In this case, the plus strands were covalently linked to the template strand and were not representative of the whole parent strand.
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PMID:Genome organization of RNA tumor viruses. I. In vitro synthesis of full-genome-length single-stranded and double-stranded viral DNA transcripts. 20 13

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 II cleaved twice to generate three fragments. Restriction endonucleases E. coli RI and Bam HI did not cleave MSV double-stranded DNA. The order of the restriction fragments was determined in relation to the 5' and 3' ends of the genomic RNA.
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PMID:Genome organization of retroviruses. III. Restriction endonuclease cleavage maps of mouse sarcoma virus double-stranded DNA synthesized in vitro. 22 90

Several newly synthesized boron betaine analogs had antitumor activity in Ehrlich ascites, Walker 256 ascites carcinosarcoma, and Lewis lung screens and marginal activity in the B-16 melanotic melanoma screen. In vivo testing demonstrated that trimethylamine-cyanoborane inhibied Ehrlich ascites cell DNA and protein syntheses as well as gene modulation by chromatin protein phosphorylation and methylation. Trimethylamine-cyanoborane increased cyclic-AMP levels. In vitro testing showed that nuclear DNA polymerase, thymidylate synthetase, S-adenosylmethyltransferase, nonhistone chromatin methylation, deoxyribonuclease, ribonuclease, and cathepsin were inhibited by the boron analogs. These compounds did not demonstrate high antitumor activity at the doses employed, but blockage of methyl transfer from S-adenosylmethionine was established as a feasible method for controlling cell proliferation.
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PMID:Boron betaine analogs: antitumor activity and effects on Ehrlich ascites tumor cell metabolism. 22 87

A DNA endonuclease, Endo-I, which cleaves superhelical DNAs, has been isolated from avian myeloblastosis virions stripped of their coats by mild detergent treatment. The enzyme has a broad pH optimum around 7.5-8.0 and requires Mg2+ for activity. A second endonuclease, Endo-II, with a requirement for Mn2+, also present in viral cores, copurified with avian myeloblastosis virus alpha beta DNA polymerase (reverse transcriptase, RNA-dependent DNA nucleotidyltransferase) and similarly cleaved superhelical DNAs. Heat denaturation and sodium fluoride and N-ethylmaleimide inhibition studies were carried out to demonstrate a possible relationship between the two endonucleases and the viral DNA polymerase and RNase H activities. It appears that Endo-II may be an intrinsic activity of the polymerase.
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PMID:DNA endonucleases associated with the avian myeloblastosis virus DNA polymerase. 22 53

Thymidine kinase (TK), DNA polymerase, and DNase activities were induced in human foreskin fibroblasts after varicella-zoster virus infection. The induced TK and DNase activities have electrophoretic mobilities different from the corresponding host enzymes. Varicella-zoster virus-induced TK was purified and separated from the host enzyme by affinity column chromatography. This enzyme has been shown to have a broader substrate specificity with respect to either the phosphate donor or acceptor as compared with human cytoplasmic and mitochondrial TKs. The best phosphate donor is ATP, with a Km of 16 microM. The Km values of thymidine, deoxycytidine, and 5-propyl deoxyuridine were estimated to be 0.4, 180, and 0.8 microM, respectively. The Ki values for several analogs of thymidine such as 5-iododeoxyuridine, arabinofuranosylthymine, 5-ethyl deoxyuridine, and 5-cyanodeoxyuridine were also examined. TTP acted as a noncompetitive inhibitor with respect to thymidine with a Ki of 5 microM. The kinetic behavior of varicella-zoster virus-induced TK is different from human cytoplasmic, human mitochondrial, and herpes simplex virus type 1- and 2-induced TKs.
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PMID:Induction of thymidine kinase and DNase in varicella-zoster virus-infected cells and kinetic properties of the virus-induced thymidine kinase. 22 52

The DNA polymerase, thymidine kinase and deoxyribonuclease activities were studied in cells infected with wild type (wt), ultraviolet (UV)-irradiated and defective herpes simplex virus type 1. All three enzymatic activities were expressed in cells infected with wt virus. In cells infected with UV-irradiated virus, the thymidine kinase and deoxyribonuclease activities were inhibited and the DNA polymerase activity was markedly suppressed. In cells producing defective virus, there was thymidine kinase activity, but the viral deoxyribonuclease activity was considerably reduced. The DNA polymerase activity was fully expressed in cells producing defective virus at passage level 5, but at passage level 6, the activity of the viral DNA polymerase declined.
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PMID:Herpes simplex virus DNA polymerase, thymidine kinase and deoxyribonuclease activities in cells infected with wild type, ultraviolet-irradiated and defective virus. 22 1


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