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)

An RNA-directed DNA polymerase was found to be associated with intracytoplasmic A-particles from DBA/2 mouse leukemia cells. The enzyme activity was detected after disrupting the purified particles with 2 M NaCl-20 mM dithiothreitol. The presence of a divalent cation and all four deoxyribonucleoside triphosphates was essential for this enzyme activity. The enzyme had a clear preference for Mg2+ over Mn2+. Cesium sulfate isopycnic gradient centrifugation of the DNA product synthesized in the actinomycin D-containing reaction revealed the presence of DNA-RNA hybrid. Furthermore, the purified DNA product was found to hybridize with RNA isolated from A-particles. These observations strongly indicate that the endogenous A-particle RNA serves as the template for the DNA polymerase.
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PMID:Characterization of an RNA-directed DNA polymerase found in association with murine intracytoplasmic A-particles. 6 24

Radioimmunological techniques were applied to the analysis of reverse transcriptase of mammalian type C RNA viruses. The polymerase of Rauscher mouse leukemia virus was purified by ion exchange and sequential affinity chromatography. Radioimmunoassays that utilized the viral enzyme as a probe detected as little as 1 ng of purified polymerase. No cross-reactivity could be demonstrated between the reverse transcriptase and other known virus-coded proteins. By comparing the immunological reactivity of the purified enzyme with the reactivity of detergent-disrupted virions, Rauscher mouse leukemia virus was shown to contain the antigenic equivalent of 40 molecules of reverse transcriptase. In a homologous competition immunoassay, the Rauscher viral enzyme demonstrated type-specific antigenic determinants, which distinguish it from other mouse type C viral polymerases. In a broadly reactive interspecies immunoassay, the reverse transcriptases of a number of mammalian type C viruses were cross-reactive, indicating their shared antigenic determinants. Various treatments that inhibit or inactivated DNA polymerase activity had little or no effect on the immunological properties of the enzyme. Thus, radioimmunoassays should be useful in the search for type C viral reverse transcriptase as a marker of subviral expression.
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PMID:Radioimmunoassay for mammalian type C viral reverse transcriptase. 6 26

This report describes the use of equilibrium gradients, RNA dependent DNA polymerase assays and electron microscopy (EM) in a combined assay for the rapid preliminary detection of intact retroviruses in crude preparations. Positive combined assays of platelets from preleukemic patients corresponded with karyotypic abnormalities found in these patients. Reconstruction experiments with Rauscher Leukemia Virus added to buffer or disrupted mouse spleen demonstrated the ease of detecting 10(9) or greater particles/g crude tissue, and the effects of buffer or added protein.
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PMID:A combined assay for the rapid preliminary detection of structural retroviruses. 7 85

Mouse antisera against calf terminal deoxynucleotidyltransferase (terminal transferase) have been prepared. The sera have been used to characterize terminal transferase both by studying inhibition of enzyme activity and by developing a competition radioimmunoassay using highly purified 125I-labeled terminal transferase. By either assay, anti-terminal transferase serum did not cross-react significantly with calf DNA polymerases alpha and beta, Escherichia coli DNA polymerase I, or the reverse transcriptase of Moloney mouse leukemia virus. The calf terminal transferase did, however, share cross-reactive but not identical determinants with human and murine terminal transferase. The radioimmunoassay could detect as little as 2 ng of terminal transferase/mg of soluble protein in a tissue extract. Thymocytes were found to contain 280 ng of terminal transferase/mg of cell protein or about 1 X 10(5) molecules/cell; bone marrow had about 1% of the level of enzyme found in thymus. Extracts of spleen, peripheral white blood cells, lymph nodes, liver, muscle, and kidney all lacked detectable antigenicity of terminal transferase. These data indicate that terminal transferase is a tissue-specific enzyme and is not related to other DNA polymerases.
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PMID:Terminal deoxynucleotidyltransferase. Serological studies and radioimmunoassay. 126 29

Within normal hemopoiesis, the intranuclear DNA polymerase TdT seems to be exclusively expressed by T and B lymphoid precursor cells. Double staining experiments showed that TdT can also be expressed in blast cells of certain acute myeloid leukemias. Recent reports described a very strong association between TdT expression and rearrangements of IgH and TcR genes in such AML specimens, suggesting a predominant lymphoid commitment of these TdT positive AML blasts. When submitting 24 serologically and morphologically well-characterized TdT positive AML specimens for additional genotypic analysis to determine the IgH and TcR gene configuration, we observed that only four had clonally rearranged IgH and/or TcR genes, whereas 20 had germ line configuration. This frequency is clearly lower than previously reported and not necessarily different from rearrangement frequencies reported for TdT negative AML (4-40%). It would seem to us, therefore, that the expression of TdT in otherwise well-defined AML blasts is not necessarily associated with a higher frequency of immunoglobulin and/or T cell receptor gene rearrangement.
Leukemia 1990 Apr
PMID:Terminal deoxynucleotidyl transferase and CD7 expression in acute myeloid leukemias are not associated with a high frequency of immunoglobulin and/or T cell receptor gene rearrangement. 169 41

The biochemical mechanisms of resistance to CRC 680578, a new antitumour chloroethylnitrosourea alpha-amino acid derivative, were studied. Alterations in DNA, RNA and protein syntheses, SH-group content, drug efflux, activities of replicative and repair enzymes, such as ribonucleotide reductase, thymidine kinase, O6-alkylguanine-DNA-alkyltransferase and DNA polymerases alpha and beta and damages of the DNA secondary structure were investigated in sensitive and resistant to CRC 680578 leukemia L1210 cells. It was found that the total SH-group number in drug-resistant cells was increased (about 1.3-fold in comparison with sensitive cells) which seems to be due to the mechanisms of drug resistance. CHC 680578 induced less pronounced inhibition and more rapid restoration of DNA and RNA synthesis in resistant cells. No differences between the ribonucleotide reductase and thymidine kinase activities were found either in intact cells of the both strains or after drug administration. The efficiency of repair of DNA chloroethyl adducts by O6-alkylguanine-DNA-alkyltransferase in leukemia cells of various sensitivity was found to be identical. The differences in enzyme activities in intact cells of the both strains were insignificant. It was supposed that factors other than changes in the level of O6-alkylguanine-DNA-alkyltransferase in leukemia cells may be responsible for the resistance to CRC 680578. The increase in the levels of DNA polymerase alpha and, especially, of DNA polymerase beta, in sensitive (but not resistant) mouse leukemia cells 48 hours after drug administration is though to define the mechanism of resistance to the new antitumour agent CHC 680578.
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PMID:[Biochemical mechanisms of resistance to a new antineoplastic drug CRC 680578 from the nitrosourea class]. 178 68

HO-221, N-[4-(5-bromo-2-pyrimidinyloxy)-3-chlorophenyl]-N'-(2- nitrobenzoyl) urea is a new benzoylphenylurea derivative. The compound exhibits significant antitumor effects against various animal tumors, and was especially effective against the solid tumors implanted subcutaneously. HO-221 inhibits DNA polymerase alpha activity strongly in vitro. In this study, we examined the cross-resistance of HO-221 to various antitumor agents using sublines of mouse leukemia. HO-221 showed antitumor effects in mice bearing L 1210 or P 388 leukemia resistant to 10 antitumor agents, DM (daunomycin), MMC (mitomycin C), CDDP (cisplatin), 5-FU (5-fluorouracil), Ara-C (cytosine arabinoside), MTX (methotrexate), CPA (cyclophosphamide), CQ (carboquone), ADM (adriamycin) and VCR (vincristine), respectively. These antitumor agents were also effective in P 388 leukemia resistant to HO-221 (P 388/HO-221). Furthermore, CDDP- and MMC-resistant sublines showed a collateral sensitivity to HO-221 in vivo. The grow the inhibitory effects were also noted in vitro in ADM-, CDDP- and MMC-resistant cells by HO-221. However, the in vitro experiments didn't show such collateral sensitivity on the resistant sublines. These results suggest that there is no cross-resistance between HO-221 and other known antitumor agents, and that HO-221 seemed to be worth for evaluating clinical usefulness.
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PMID:[Cross-resistance of HO-221 and various antitumor agents in sublines of mouse leukemia]. 189 47

Exponentially growing human lymphoblasts (culture LS-2) were separated by cell sorting (FACS II, Becton Dickinson) according to their deoxyribonucleic acid (DNA) content, designating them at particular phases of the cell cycle. Prior to cell sorting the DNA has been fluorochrome-labeled with the Hoechst stain H 33342. Maximum cell enrichments of 94% for G0 + G1 cells, 96% for S cells and 74% for G2 + M cells could be achieved. The enzyme activities of thymidine kinase (TK), thymidylate synthase (TS), DNA polymerase (DNA-P), dihydrofolate reductase (FH2-R), methionine synthase (MS), and hexokinase (HK) were determined in the obtained cell fractions. Although incorporation of 3H-thymidine (3H-dTR) and the 3H-dTR labeling index were significantly inhibited by the dye, no evidence of cell staining's having a significant effect on the enzyme activities was found. The enzyme activities for approximately 100% pure G0 + G1, S, and G2 + M cells were computed. With exception of TK, all the enzymes under study were shown to exhibit activities--although of differing degree--in the G0 + G1, S, and G2 + M cells. No TK activity was shown in G0 and G1 cells; its activity, however, was approximately the same in S and G2 + M cells. This applies likewise for TS which, in contrast to TK, exhibits minor activity in G0 + G1 cells. DNA-P was highly active in G0 + G1 cells, but maximum activity was in S cells. FH2-R exhibited maximum activity in S cells, although the difference in activity between S and G2 + M cells was not significant. None of the observed differences in MS activity was significant, indicating equally high activity in cells of all cell cycle phases. HK activity is approximately twice as high in G2 + M cells as in G0 + G1 cells.
Leukemia 1989 May
PMID:Relation between cell cycle stage and the activity of DNA-synthesizing enzymes in cultured human lymphoblasts: investigations on cells separated according to DNA content by way of a cell sorter. 271 50

Undifferentiated human lymphoblasts (culture LS-2) were separated according to cell size during their exponential growth phase by way of centrifugal elutriation. The cell fractions thus obtained were characterized in terms of different cell cycle stages by flow cytometric measurement of their deoxyribonucleic acid (DNA histogram), the [3H]thymidine labeling index, and by determining the rate of [3H]thymidine incorporation. In these cell fractions the activities of thymidine kinase, thymidylate synthase, DNA polymerase, dihydrofolate reductase, methionine synthase, and hexokinase were determined. The results showed that all the enzymes investigated exhibited activities in all cell fractions. With the exception of DNA polymerase, all of the enzymes exhibited the lowest level of activity in the fraction containing the highest proportion of G0 + G1 phase cells (fraction 2); the activity of thymidine kinase was particularly low. This would suggest that thymidine kinase is not active in G0 + G1 phase cells and that the activity measured in fraction 2 is perhaps attributable to contamination of this fraction by S and G2 + M phase cells.
Leukemia 1987 Mar
PMID:Relation between cell cycle stage and the activity of DNA-synthesizing enzymes in cultured human lymphoblasts: investigations on cell fractions enriched according to cell cycle stages by way of centrifugal elutriation. 366 41

Polyribonucleotides will act as efficient templates for the DNA polymerases found in the virions of avian myeloblastosis virus and mouse leukemia virus if a short complementary oligodeoxyribonucleotide primer is added. Synthesis of the complementary polydeoxyribonucleotide continues until an amount of polymer equal to the amount of initial template has been produced. The two viruses show slightly different specificities toward the four homoribopolymers. Polydeoxyribonucleotides are generally much poorer templates than the homologous polyribonucleotides, in most cases yielding no detectable synthesis. The DNA polymerase of RNA tumor viruses, therefore, have the same requirements for activity as do other DNA polymerases, except that they prefer polyribonucleotides over polydeoxyribonucleotides as templates.
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PMID:Primer requirement and template specificity of the DNA polymerase of RNA tumor viruses. 432 4


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