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 effect of Rolly No. 11 strain herpes simplex virus infection of HeLa cells in culture on deoxynucleotide metabolism and the level of various enzymes concerned with the biosynthesis of DNA has been investigated. Of 18 enzyme activities studied, thymidine kinase, DNA polymerase and deoxyribonuclease were markedly augmented, a finding in agreement with previous reports. Deoxycytidine kinase, ribonucleotide reductase, thymidylate kinase and deoxycytidylate deaminase activities, in contrast with previous reports, did not increase; the activities of the other enzymes studied, also did not increase. Whereas most of the radioactivity derived from [14-C] thymidine in the acid-soluble fraction of the uninfected cells was present as deoxythymidine triphosphate, that present in the infected cells was primarily in the form of deoxythymidine monophosphate. Thus, in the infected cell deoxythymidylate kinase is a rate-limiting enzyme in the biosynthesis of deoxythymidine triphosphate. A marked increase in the pools of the four naturally occurring deoxynucleoside triphosphates (dTTP, dCTP, dATP, dGTP) was found. The rate of formation of the virus-induced enzymes was determined, as were the various nucleoside triphosphate pools and the other phosphorylated derivatives of thymidine; a maximum was reached for all these csmponents between 6 to 8 h post infection. Although an apparent greater synthesis of DNA occurred in the uninefected cells, when the specific activity of the radioactive deoxythymidine triphosphate was taken into account, there was actually a greater rate of DNA synthesis in the infected cells, with the peak at 8 h post infection.
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PMID:Deoxyribonucleotide metabolism in Herpes simplex virus infected HeLa cells. 16 49

Thymidine kinase, dTMP kinase, and DNA polymerase activities were determined in cell lines of AH hepatoma, L1210 leukemia, and Yoshida sarcoma that were sensitive and resistant to 5-fluorouracil (5-FU). It was found that the levels of these enzymes in tumor cells were not consistently related to the property of sensitivity to 5-FU. A marked difference was observed between sensitive and resistant cell lines of L1210 leukemia and Yoshida sarcoma in the uptake of labeled 5-FU into the acid-soluble, nucleotide, and RNA fractions, the rate of incorporation of 5-FU into these fractions being 3 to 5 times greater in sensitive tumor cells than in resistant tumor cells. The radioactivities in the acid-soluble fractions of AH44 (sensitive) and AH109A (resistant) were similar after incubation of these cells with labeled 5-FU in vitro. However, a smaller volume of ascites and lower cell number were observed in AH44 (sensitive)-bearing rats than in AH109A (resistant)-bearing rats. These in vivo results indicate that the 5-FU injected intraperitoneally was diluted by ascites more in AH109A (resistant)-bearing rats than in AH44 (sensitive)-bearing rats.
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PMID:Metabolism of 5-fluorouracil in sensitive and resistant tumor cells. 55 50

Thmidine (TdR) incorporation into DNA increased in the livers and spleens of rats bearing Yoshida sarcoma (solid type) or AH130 (solid type). TdR kinase and DNA polymerase activities increased in the serum, liver, and spleen of these rats, while thymidine monophosphate kinase activity increased appreciably only in the liver and spleen. On diethylaminoethyl cellulose column chromatography, 2 peaks of TdR dinase activity were separated from the serum and tumor tissues of rats bearing Yoshida sarcoma (solid type) while only 1 peak was obtained from the liver. TdR kinase activity in the serum decreased abruptly 7 hr after removal of the Yoshida sarcoma, while that in the liver decreased more slowly.
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PMID:DNA synthesis in tumor-bearing rats. 111 20

During the fractionation of various enzymes concerned with DNA synthesis from the postmicrosomal supernatant fraction of various tissues, DNA polymerace [EC 2.7.7.7], thymidine kinase [EC 2.7.1.75], dTMP kinase [EC 2.7.4.9], deoxycytidine kinase [EC 2.7.1.74], and deoxycytidine monophosphokinase (dCMP kinase) [EC 2.7.4.14] were found in the pellet fraction of postmicrosomal supernatant. Further, the uridine kinase [EC 2.7.1.48] and aspartate transcarbamylase [EC 2.1.3.2] activities of postmicrosomal supernatant from various tissues were also present in this pellet fraction. The activities of DNA polymerase, thymidine kinase, uridine kinase, and aspartate transcarbamylase from normal and regenerating rat liver, and Yoshida sarcoma were higher in the pellet fraction than in the supernatant. On the other hand, the activities of dTMP kinase, dCMP kinase, and orotidine-5'-phosphate decarboxylase [EC 4.1.1.23] were lower in the pellet fraction than in the supernatant. The pellet fractions of regenerating rat liver and Yoshida sarcoma showed a remarkable incorporation of various precursors (thymidine, dTMP, deoxycytidine, and dCMP) into DNA in the presence of a suitable DNA template, ATP and all four deoxynucleoside 5'-triphosphates for DNA synthesis. Normal adult rat liver catalyzed a much smaller incorporation of all these precursors, except for dCMP.
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PMID:Intracellular distribution of various enzymes concerned with DNA synthesis from normal and regenerating rat liver, and Yoshida sarcoma. 113 86

Cis-diaminedichloroplatinum(II) [cDDP] and three related derivatives Pt(mal)(NH3)2, PtCl2(dach) and Pt(mal) (dach) have been observed to possess cytotoxicity against the growth of P388 lymphocytic leukemia cells. DNA synthesis in P388 cells was inhibited by the agents in a manner which was consistent with their ED50 values for cytotoxicity. When P388 cells were treated with these platinum complexes in vitro at doses which caused more than 80% inhibition of DNA synthesis, no significant inhibition was observed for thymidine, kinase, thymidine monophosphate kinase, carbamoyl phosphate synthetase, or aspartate transcarbamoylase activities. Thus, there was no evidence that these agents inhibited de novo purine, pyrmidine, or deoxynucleotide synthesis. All of the agents did inhibit the nuclear DNA polymerase activity, but the extent of inhibition was 20% or less at doses which caused greater than 70% inhibition of DNA synthesis. Thus, the inhibition of DNA synthesis appeared to be due to cisplatinum(II) drug binding to the DNA bases. This was estimated to be 1 atom of platinum per 1500-3000 DNA base pairs which is consistent with other studies. The platinum complexes with chloro leaving ligands caused considerable DNA strand scission by 24 h at 10 times the ED50 dose, most likely a measure of impending cell death. In contrast, the platinum complexes with malonato leaving ligands did not cause significant strand scission by 24 h at similar doses. They also exhibited a significant delay in the inhibition of DNA synthesis. These data were interpreted as resulting from slower monoadduct to diadduct conversion, but it is not possible to eliminate the possibility of a different mode of interaction with DNA or a different mechanism of cytotoxicity for the malonato compounds.
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PMID:Inhibition of nucleic acid synthesis in P388 lymphocytic leukemia cells in culture by cis-platinum derivatives. 170 16

cis-Diamminedichloroplatinum(II) (cisplatin; cDDP) derivatives were found to afford T/C% values greater than 200 against the growth of P388 lymphocytic leukemia cells in vivo. The parent compound, cDDP, preferentially inhibited DNA synthesis. The RNA synthesis was elevated, whereas protein synthesis was unaffected after two or three daily ip doses. Radiolabeled drug studies demonstrated cellular uptake and binding of cDDP derivatives to the DNA molecule. cis-Diamminedichloroplatinum(II) (cDDP) treatment resulted in DNA strand scission after a single dose, but caused cross-linking of DNA strands after two or three ip doses. There was an accumulation of deoxynucleoside triphosphates [d(NTP)s] on day 2 and 3, indicating that incorporation of nucleotides into the DNA strand had been blocked. Thymidine kinase, thymidine monophosphate kinase, carbamoyl phosphate synthetase, and aspartate transcarbamoylase activities were inhibited in vivo after three doses of cDDP at 1.5 mg/kg/day. However, only the inhibition of a cytoplasmic preparation of DNA polymerase alpha by cDDP appeared to be directly related to the inhibition of DNA synthesis and the accumulation of d(NTP) pool levels. Thus, the primary target for cDDP appears to be DNA itself, although direct inhibition of DNA polymerase alpha may play a minor role in the inhibition of DNA replication by cDDP.
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PMID:Inhibition of DNA synthesis in P388 lymphocytic leukemia cells of BDF1 mice by cis-diamminedichloroplatinum(II) and its derivatives. 228 Mar 54

The thymidine analog 3'-azido-3'-deoxythymidine (BW A509U, azidothymidine) can inhibit human immunodeficiency virus (HIV) replication effectively in the 50-500 nM range [Mitsuya, H., Weinhold, K. J., Furman, P. A., St. Clair, M. H., Nusinoff-Lehrman, S., Gallo, R. C., Bolognesi, D., Barry, D. W. & Broder, S. (1985) Proc. Natl. Acad. Sci. USA 82, 7096-7100]. In contrast, inhibition of the growth of uninfected human fibroblasts and lymphocytes has been observed only at concentrations above 1 mM. The nature of this selectivity was investigated. Azidothymidine anabolism to the 5'-mono-, di-, and -triphosphate derivatives was similar in uninfected and HIV-infected cells. The level of azidothymidine monophosphate was high, whereas the levels of the di- and triphosphate were low (less than or equal to 5 microM and less than or equal to 2 microM, respectively). Cytosolic thymidine kinase (EC 2.7.1.21) was responsible for phosphorylation of azidothymidine to its monophosphate. Purified thymidine kinase catalyzed the phosphorylations of thymidine and azidothymidine with apparent Km values of 2.9 microM and 3.0 microM. The maximal rate of phosphorylation with azidothymidine was equal to 60% of the rate with thymidine. Phosphorylation of azidothymidine monophosphate to the diphosphate also appeared to be catalyzed by a host-cell enzyme, thymidylate kinase (EC 2.7.4.9). The apparent Km value for azidothymidine monophosphate was 2-fold greater than the value for dTMP (8.6 microM vs. 4.1 microM), but the maximal phosphorylation rate was only 0.3% of the dTMP rate. These kinetic constants were consistent with the anabolism results and indicated that azidothymidine monophosphate is an alternative-substrate inhibitor of thymidylate kinase. This conclusion was reflected in the observation that cells incubated with azidothymidine had reduced intracellular levels of dTTP. IC50 (concentration of inhibitor that inhibits enzyme activity 50%) values were determined for azidothymidine triphosphate with HIV reverse transcriptase and with immortalized human lymphocyte (H9 cell) DNA polymerase alpha. Azidothymidine triphosphate competed about 100-fold better for the HIV reverse transcriptase than for the cellular DNA polymerase alpha. The results reported here suggest that azidothymidine is nonselectively phosphorylated but that the triphosphate derivative efficiently and selectively binds to the HIV reverse transcriptase. Incorporation of azidothymidylate into a growing DNA strand should terminate DNA elongation and thus inhibit DNA synthesis.
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PMID:Phosphorylation of 3'-azido-3'-deoxythymidine and selective interaction of the 5'-triphosphate with human immunodeficiency virus reverse transcriptase. 243 Feb 86

In tissues obtained from patients undergoing gastrectomy, the activities of 12 enzymes involved in pyrimidine nucleotide synthesis: cytidine triphosphate (CTP) synthetase, deoxycytidine monophosphate (dCMP) deaminase, thymidine monophosphate (dTMP) kinase, uridine (Urd), deoxycytidine (dCyd) and thymidine (dThd) kinases, Urd, deoxyuridine (dUrd) and dThd phosphorylases, cytidine (Cyd) and dCyd deaminases, and DNA polymerase were examined in the eight-well-differentiated and 12 poorly differentiated gastric cancer tissues and the ten normal tissues. These cases were clinically advanced and serosal invasions were evident. Activities of these enzymes were higher in the poorly differentiated tissues than the well differentiated type and in the normal tissues. Significant differences were noted between the poorly differentiated and well-differentiated types, in dTMP kinase (P less than 0.02), dThd kinase (P less than 0.05), dThd phosphorylase (P less than 0.01), and DNA polymerase (P less than 0.05). The authors' findings show that the level of pyrimidine nucleotide synthesis, in both de novo and salvage pathways, is higher in the poorly differentiated gastric cancer tissues than in the well-differentiated type and suggest that antitumor drugs have an increased susceptibility in cases of poorly differentiated gastric carcinoma.
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PMID:Pyrimidine nucleotide synthesis is more extensive in poorly differentiated than in well-differentiated human gastric carcinoma. 291 Apr 29

A series of amine cyanoboranes, amine carboxyboranes, and boron analogues of alpha-amino acids have been investigated for antineoplastic activity against the growth of Ehrlich ascites cells. Additional studies demonstrated that the boron analogues inhibited DNA and RNA synthesis at 300 microM. The suppression of DNA synthesis of Ehrlich ascites cells correlated with the reduction of DNA polymerase, 5-phosphoribosyl-1-pyrophosphate amidotransferase, and dihydrofolate reductase activities afforded by the boron compounds. These derivatives did not suppress protein synthesis, thymidylate synthetase, or thymidine monophosphate kinase activities as previously reported for some boron antineoplastic agents.
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PMID:Antineoplastic activity of a series of boron analogues of alpha-amino acids. 403 49

Infectious deoxyribonucleic acid (DNA) was extracted from green monkey kidney (CV-1) cultures at various times after the cultures were infected with simian virus 40 (SV40) at input multiplicities of 0.01 and 0.1 plaque-forming unit (PFU) per cell. A pronounced decrease in infectious DNA was observed from 3 to 16 hr after virus infection, suggesting that structurally altered intracellular forms may have been generated early in infection. Evidence is also presented that SV40 DNA synthesis requires concurrent protein synthesis. DNA replication was studied in the presence and absence of cycloheximide in: (i) SV40-infected and uninfected cultures of CV-1 cells; (ii) cultures synchronized with 1-beta-d-arabinofuranosylcytosine (ara-C) for 24 to 30 hr prior to the addition of cycloheximide; and (iii) in heterokaryons of SV40-transformed hamster and susceptible monkey kidney cells. DNA synthesis was determined by pulse-labeling the cultures with (3)H-thymidine at various times from 24 to 46 hr after infection. In addition, the total infectious SV40 DNA was measured. Addition of cycloheximide, even after early proteins had been induced, grossly inhibited both SV40 and cellular DNA syntheses. The activities of thymidine kinase, DNA polymerase, deoxycytidylate deaminase, and thymidylate kinase were measured; these enzyme activities remained high for at least 9 hr in the presence of cycloheximide. SV40 DNA prelabeled with (3)H-thymidine before the addition of cycloheximide was also relatively stable during the time required for cycloheximide to inhibit further DNA replication.
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PMID:Simian virus 40 deoxyribonucleic acid replication. I. Effect of cycloheximide on the replication of SV40 deoxyribonucleic acid in monkey kidney cells and in heterokaryons of SV40-transformed and susceptible cells. 430 1


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