Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the effect of the natural marine substance illimaquinone on the catalytic activities of reverse transcriptase from human immunodeficiency virus type 1. Illimaquinone inhibited the RNase H activity of the enzyme at concentrations of 5 to 10 microgram/ml, whereas RNA-dependent DNA polymerase and DNA-dependent DNA polymerase activities were considerably less susceptible to this inhibition. Two synthetic derivatives of illimaquinone, in which the 6'-hydroxyl group at the ortho position to one of carbonyl groups of the quinone ring was modified, proved ineffective in inhibiting the human immunodeficiency virus type 1 reverse transcriptase RNase H function, suggesting involvement of the 6'-hydroxyl group in blocking the enzymatic activity.
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PMID:Illimaquinone, a selective inhibitor of the RNase H activity of human immunodeficiency virus type 1 reverse transcriptase. 170 12

We and others previously reported DNA polymerase activity in culture supernatants of peripheral blood mononuclear cells from patients with acute Kawasaki syndrome (KS). In the present study, we further characterized the previously detected polymerase activity and attempted to confirm its presence in cultured peripheral blood mononuclear cells from additional patients with KS. Characterization experiments indicated that the polymerase activity was typical of a DNA-dependent DNA polymerase rather than viral reverse transcriptase. Peripheral blood mononuclear cell cultures from 17 additional KS patients were negative for reverse transcriptase activity in three laboratories. Our findings do not provide support for a retroviral etiology of KS. Further studies should continue to focus on infectious agents in efforts to elucidate the etiology of KS.
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PMID:Failure to confirm the presence of a retrovirus in cultured lymphocytes from patients with Kawasaki syndrome. 171 54

The RNA- and DNA-dependent DNA polymerase activities of two point mutants of HIV-1 reverse transcriptase lacking ribonuclease H activity have been compared to the wild-type enzyme activities using substrates consisting of an oligodeoxynucleotide primer hybridized to either a RNA or a DNA template. The RNase H phenotype had a negligible effect on the steady-state kinetics and processivity of reverse transcription of a homopolymer template-primer [poly(A).oligo(dT)]. However, analysis of the distribution of DNA products indicated that the ability of the mutants to reverse-transcribe a specifically primed 345-nucleotide heteropolymeric RNA template derived from the gag region of HIV-1 was impaired relative to the wild-type enzyme. Although the wild-type and mutant enzymes shared the same pause sites of synthesis along the RNA template, certain prematurely terminated nascent primer chains were poorly extended by the mutant enzymes and hence accumulated, suggesting that a catalytically functional RNase domain facilitated reinitiation of DNA synthesis at specific pause sites along a heteropolymer template. In contrast, the processivity and product distribution of DNA synthesis directed by a heteropolymer gag DNA template of the same nucleotide sequence were not significantly influenced by the RNase H phenotype of the mutants.
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PMID:Analysis of the RNA- and DNA-dependent DNA polymerase activities of point mutants of HIV-1 reverse transcriptase lacking ribonuclease H activity. 171 22

We have constructed a series of plasmids which, when introduced into Escherichia coli, induce the overexpression of soluble wild-type and mutated forms of the reverse transcriptases (RTs) from human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2, respectively). These proteins were analyzed previously for their RNA-dependent DNA polymerase (RDDP) and ribonuclease H (RNase H) activities. In the present study we assayed the different mutant RTs for their DNA-dependent DNA polymerase (DDDP) activity, employing an in situ polyacrylamide gel activity assay. The results indicate that both the RDDP and DDDP catalytic functions of HIV-1 RT mutants are affected similarly by mutations suggesting a high degree of overlap between the catalytic domains involved in both activities. Contrariwise, many of the HIV-2 RT mutants display no correlation between these two DNA polymerase activities, that is, the DDDP activity was not affected by the mutations introduced in the native enzyme in contrast to the RDDP activity. We were thus able to generate mutants of HIV-2 RT that unlike the wild-type RT, are capable of transcribing only DNA and not RNA. The disparity in mutational-catalytic relations between the two HIV-related RTs may reflect a possible difference in the structure and folding properties of the two proteins.
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PMID:The DNA-dependent and RNA-dependent DNA polymerase activities of the reverse transcriptases of human immunodeficiency viruses types 1 and 2. 172 5

The RNA-dependent DNA polymerase (RDDP) of human immunodeficiency virus (HIV) was purified from sucrose density gradient-banded virus by four successive procedures: anion exchange chromatography, cation exchange chromatography, affinity chromatography on oligo(dT)-cellulose and adsorption chromatography on hydroxyapatite. The enzyme preparation was free of cellular DNA-dependent DNA polymerase activity. The properties of HIV RDDP were determined with a variety of template-primers. Generally, the enzyme used Mg2+ for optimal activity except with (Cm)n X (dG)12-18 as template-primer. Kinetic data (Michaelis constant, Hill coefficient) were calculated for several substrates.
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PMID:Functional purification and enzymic characterization of the RNA-dependent DNA polymerase of human immunodeficiency virus. 243 65

The DNA polymerase of hepadnaviruses has two different functions during virus replication. It acts both as an RNA-dependent DNA polymerase (reverse transcriptase) and as a DNA-dependent DNA polymerase. Duck hepatitis B virus (DHBV) preparations were used to investigate the inhibitory effects of selected compounds on these two enzyme activities. The reverse transcriptase activity was represented by an actinomycin D-resistant, phosphonoformate-sensitive DNA polymerase activity isolated from DHBV-infected duck livers. DHBV from serum was used as the source of the DNA-dependent DNA polymerase activity. Pyrophosphate and nucleoside triphosphate analogs were assayed for their inhibitory effects on the two enzyme preparations. A marked inhibition was obtained with 3'-fluoro-2',3'-dideoxythymidine 5'-triphosphate, acyclovir triphosphate, 2',3'-dideoxythymidine 5'-triphosphate, 2',3'-dideoxyguanosine 5'-triphosphate and 2',3'-dideoxythymidine 5'-triphosphate. The two thymidine analog triphosphates showed a markedly lower inhibitory effect on the reverse transcriptase activity than on the DNA-dependent DNA polymerase activity. This was in analogy with earlier findings with 3'-azido-2',3'-dideoxythymidine 5'-triphosphate. Among the tested pyrophosphate analogs only phosphonoformate was inhibitory.
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PMID:Inhibition of RNA- and DNA-dependent duck hepatitis B virus DNA polymerase activity by nucleoside and pyrophosphate analogs. 248 79

Replication of hepadnaviruses involves a viral DNA polymerase containing both a DNA-dependent and an RNA dependent activity. This polymerase is a potential target for chemotherapy against hepatitis B. We have used human hepatitis B virus DNA-dependent DNA polymerase from human serum and duck hepatitis B virus DNA-dependent DNA polymerase from duck serum as well as RNA-dependent DNA polymerase activity from duck hepatitis B-infected duck liver. Triphosphates of thymidine analogs have been synthesized and tested for their inhibitory activities against these enzymes with the intention both to explore differences between these enzymes and structural requirements for inhibitors. The results showed that with the inhibitors tested, hepatitis B virus DNA-dependent DNA polymerase was the most sensitive enzyme and the triphosphate of 5-propenyl-2'-deoxyuridine was the most active inhibitor. In addition, the 5'-triphosphate of 5-propenyl-arabinofuranosyluracil also inhibited the hepadnavirus DNA-dependent DNA polymerases, and was a competitive inhibitor with respect to 2'-deoxythymidine triphosphate as showed by kinetic studies with duck hepatitis B virus DNA-dependent DNA polymerase from serum. Pharmacokinetic analysis showed 5-propenyl-2'-deoxyuridine to be well absorbed orally, but rapidly cleared from plasma. The arabinofuranosyl analog was also well absorbed but cleared less rapidly. Hence, these results indicate the potential of 5-propenyl-2'-deoxyuridine and 5-propenyl-arabinofuransyluracil for chemotherapy of hepatitis B.
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PMID:Inhibition of human hepatitis B virus DNA polymerase and duck hepatitis B virus DNA polymerase by triphosphates of thymidine analogs and pharmacokinetic properties of the corresponding nucleosides. 314 22

The DNA polymerase of the Prague strain of Rous sarcoma virus of subgroup C and of the Schmidt-Ruppin strain of subgroup A has been solubilized. DNA polymerase purified by sucrose gradient sedimentation and chromatography on DEAE-cellulose represented less than 2% of the soluble [(14)C]protein of the virus. The enzyme was separated from 90% of the viral glycoprotein; it is probably different from the viral group-specific antigen. The sedimentation coefficient (s(20, w)) of the soluble DNA polymerase was 8 S before, and 6 S after, incubation with pancreatic RNase. The molecular weight of the 8S DNA polymerase was estimated to be about 170,000, and that of the 6S DNA polymerase to be about 110,000. Purified DNA polymerase had a high activity with 60-70S viral RNA or salmon DNA as template, but it had a low activity with heat-dissociated 60-70S RNA, influenza virus RNA, or the RNA of tobacco mosaic virus as template. Neither the 8S nor the 6S DNA polymerase had endogenous template activity. The DNA-dependent and the RNA-dependent DNA polymerase activities of the Prague strain coincided in sucrose gradients, both in the 8S and the 6S form. It is concluded that the RNA-dependent and the DNA-dependent DNA polymerase activities of the avian tumor viruses are probably due to the same enzyme.
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PMID:Properties of a soluble DNA polymerase isolated from Rous sarcoma virus. 432 88

An RNA-dependent DNA polymerase was isolated from purified virions of endogenous oncornaviruses released by the MOPC-315 murine myeloma cell line. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified enzyme was found to consist of two major polypeptides with molecular weights of about 28,000 and 26,500. The active enzyme had a molecular weight of approximately 56,000, as calculated from its sedimentation on glycerol density gradients, indicating that it is probably a dimer of the two subunit polypeptides. The isolated MOPC-315 virus polymerase exhibited all three activities known to be found in the DNA polymerase from oncornaviruses, namely, an RNA-dependent DNA polymerase, a DNA-dependent DNA polymerase, and an RNase H. The RNA-dependent polymerase activity showed a prounced preference for Mn2+ over Mg2+, whereas the DNA-dependent and RNase H reactions were catalyzed by these two cations to an almost equal extent. The purified polymerase was found to be immunologically related to the polymerase of Rauscher murine leukemia virus.
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PMID:RNA-dependent DNA polymerase of an endogenous type C virus of mice: purification and partial characterization. 615 78

The activities of RNA-dependent DNA polymerase and DNA-dependent DNA polymerase were measured in hippocampus of fast and slow learning Wistar rats. The RNA-dependent DNA polymerase activity in the hippocampus of fast learning rats exceeds two-fold that in the slow learning ones, while the rates of the DNA-dependent DNA polymerase activities are similar. A significant increase in RNA-dependent DNA polymerase only was found in the hippocampus of rats 20 min after training for the conditioned food response before the trace consolidation registered 40 min after the training session. The data obtained are consistent with the suggestion that reverse transcription plays an important role in memory consolidation.
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PMID:Probable role of reverse transcription in learning: correlation between hippocampal RNA-dependent DNA synthesis and learning ability in rats. 619 Dec 60


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