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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At concentrations of 7 times 10(-6) to 7 times 10(-5) M, derivatives consisting of the polycylic ring structures fluoranthene, fluorenone, fluorene, anthraquinone, xanthenone, and dibenzofuran with appropriate amine side chains inhibited by over 90% the purified RNA-directed DNA polymerase of avian myeloblastosis virus acting on poly(deoxyadenylate-deoxythymidylate) [poly(dA-dT)]. Of these, only the fluoranthene derivatives were strong inhibitors of the viral DNA polymerase directed by polyadenylate-oligodeoxythymidylate [poly(A)-(dT)12-18]. Low levels of fluoranthene derivatives (1 times 10(-5) M) also strongly inhibited polymerase with polyinosinate-oligodeoxycytidylate [poly(I)-(dC)12-18], activated calf thymus DNA, and viral 70S RNA as templates, but not with polycytidylate-oligodeoxyguanylate as template. A comparison of the activity of 11 fluoranthene derivatives with different side chains showed that the structure of the amine side chain influenced both the extent of antipolymerase activity with a given template and the relative inhibition with different synthetic DNA and RNA templates. The naturally occurring polyamines, spermine, spermidine, and putrescine, did not inhibit the activity of the viral DNA polymerase. Studies on the mechanism of action indicated that the synthetic derivatives inhibited polymerase activity by binding to the template and not to the enzyme: 1) inhibition by fluoranthene derivatives was overcome by the addition of excess template including poly(dA-dT), poly(A)-(dT)12-18, poly(I)-(dC)12-18, viral 70S RNA, and activated calf thymus DNA; 2) the degree of inhibition by fluoranthene derivatives was unaffected by the addition of the creased viral DNA polymerase; 3) with the same template, Escherichia coli DNA-directed RNA polymerase and the viral RNA-directed DNA polymerase were inhibited to about the same extent; and 4) the derivatives formed a complex with DNA, poly(I), and poly(A) that was stable to exclusion chromatography on Sephadex G-100. Several derivatives also had biologic activity, since they blocked the ability of the murine sarcoma virus to transform cells.
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PMID:Inhibition of purified DNA polymerase of RNA tumor viruses by fluoranthene derivatives and analogues of tilorone hydrochloride. 5 Oct 87

RNA tumor virus-specific DNA in cells can be detected by its capacity to 1) alter the reassociation kinetics of labeled double-stranded product of viral RNA-directed DNA polymerase; 2) anneal single-stranded DNA (cDNA) synthesized by viral polymerase; or 3) hybridize labeled viral 70S (genomic) RNA. Duplexes formed with these procedures can be analyzed for fidelity of base pairing, and the integration of viral DNA into the host genome can be established with a simple but stringent technique. We illustrate this methodology as applied to detection of Rous sarcoma virus (RSV)-specific DNA in XC cells and of mouse mammary tumor virus (MMTV)-specific DNA in murine and human tissues.
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PMID:Detection and characterization of RNA tumor virus-specific DNA in cells. 5 30

Certain human milks have been shown to contain particles that have the biochemical and biophysical properties that are diagnostic of the known RNA tumor viruses of animals. These properties include 1) a particle density of 1.16-1.19 g/ml 2) a viral reverse transcriptase (RNA-directed DNA polymerase), and 3) a high molecular weight (HMW) 60-70S RNA that contains polyadenylic regions of 200 nucleotides in length. Inner cores, or nucleoids, of these particles have been isolated. They have a density of 1.26-1.27 g/ml and contain the viral reverse transcriptase and 60-70S RNA. Using molecular hybridization, a specific homology was demonstrated between radioactive DNA synthesized from the RNA of the human milk particle and the RNA from human malignant breast tumors. RNA from benign breast tumors and other human tissues were negative in these tests.
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PMID:Evidence for an RNA tumor viruses in human milk. 5 33

Reticuloendotheliosis virus (REV) contains an endogenously instructed, RNA-directed DNA polymerase activity. Both the endogenous and exogenous DNA polymerase activities exhibited up to 10-fold greater activity at the optimum concentration of manganous ion (0.025 mM for exogenous; 0.25 mM for endogenous) than at any concentration of magnesium ion. Antiserum to the DNA polymerase of an REV group virus (spleen necrosis virus) inhibited both endogenous and exogenous DNA polymerase activity of REV, whereas antiserum to the Rous sarcoma virus (Rous-associated virus-0) [RSV(RAV-0)]DNA polymerase did not. The DNA product of the endogenous reaction is associated with the high-molecular-weight RNA of REV and anneals with REV RNA but not with RNA from Rous sarcoma virus.
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PMID:RNA-directed DNA polymerase activity of reticuloendotheliosis virus: characterization of the endogenous and exogenous reactions. 5 35

Reticuloendotheliosis viruses (REV) contain an endogenous RNA-directed DNA polymerase activity. The endogenous DNA polymerase activity can be elicited in purified preparations of REV by treatment with nonionic detergents. The enzyme activity has a strong preference for manganous ions. Therefore, appreciable endogenous DNA polymerase activity can be demonstrated only if the reaction mixture contains appropriate concentrations of manganous ions. Enzyme activity can be inhibited by pretreatment with RNase or deletion of one or more deoxyribonucleoside triphosphates from the reaction mixture. In contrast, actinomycin D has little effect in initial DNA synthesis. The results from both velocity and equilibrium centrifugation indicate that the nascent chains of product DNA are associated with 60S viral RNA. The DNA product of the endogenous DNA polymerase reaction is hybridizable to REV RNA, but not to avian leukosis virus RNA.
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PMID:Characterization of endogenous RNA-directed DNA polymerase activity of reticuloendotheliosis viruses. 5 36

Particles with the density and enzymatic activity characteristic of known oncornavirus have been previously described in bone marrow cells from patients with leukemia in relapse and in remission. We have confirmed these findings and studied two patients in whom preleukemia was among the diagnostic considerations. Following cultivation of bone marrow from these patients for 1 week in conditioned media with dexamethasone, a high-speed pellet of the supernatant fluid and disrupted cells was prepared and analyzed on a sucrose gradient for enzymatic activity characteristic of RNA-directed DNA polymerase (reverse transcriptase). Peaks of endogenous DNA polymerase activity showing ribonuclease sensitivity and/or stimulation with the synthetic template poly(rC)-(dG)12-18 were demonstrated in both patients at densities of 1.15 to 1.19 and 1.21 to 1.24 g/ml. Subsequently, diagnosis 2 and 4 months after initial evaluation revealed acute myelogenous leukemia and malignant histiocytosis, respectively. Prior studies have suggested a possible etiological significance of such particles in human leukemia. The demonstration of similar particles preceding clinically overt disease in these patients supports this hypothesis and offers the possibility of early diagnosis and treatment.
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PMID:Oncornavirus-like particles from cultured bone marrow cells preceding leukemia and malignant histiocytosis. 5 58

DNA transcripts, ranging from 1,500 to 4,500 nucleotides in length, can be identified in the DNA product synthesized in vitro by the Rous sarcoma virus-associated RNA-directed DNA polymerase. Although these DNA transcripts are considerably larger than the size classes of the DNA product previously reported, they only represent a minor proportion (less than 5%) of the total DNA synthesized in standard reaction mixtures containing rate-limiting concentration of one of the four deoxynucleoside triphosphates. However, the proportion of these larger transcripts relative to the total DNA product increases substantially when the enzymatic synthesis of DNA is performed in the presence of equimolar concentrations of deoxynucleoside triphosphate precursors. Both rate-zonal sedimentation in alkaline sucrose and nucleic acid hybridization techniques have confirmed the length and genetic complexity of these larger DNA transcripts. The identification of large DNA chains in the DNA product synthesized in vitro by the avian oncornavirus RNA-directed DNA polymerase provides an explanation for the paradox that exists between the limited number of primer sites per 70S RNA genome, the small size of the bulk of the DNA product, and the extent of the Rous sarcoma virus genome represented by the DNA product.
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PMID:In vitro transcription of DNA from the 70S RNA of Rous sarcoma virus: identification and characterization of various size classes of DNA transcripts. 5 25

Type-C RNA tumor virus particles were released from three different human lymphoblastoid cell lines after incubation in arginine-deficient medium. The released virus-like particles were characterized by (a) their ability to band in sucrose gradients at a density of 1.16-1.18 g/ml; (b) the presence of an RNA-directed DNA polymerase activity resembling that of the oncornaviruses; and (c) isolation of cores that band at a density of 1.26-1.27 g/ml in sucrose gradients. Examination of the arginine-deprived human lymphoblastoid cell line strain P3HR-1 by electron microscopy revealed the presence of C-type particles in the intracellular spaces.
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PMID:Oncornavirus-like particles released from arginine-deprived human lymphoblastoid cell lines. 5 42

A preliminary analysis of an RNA-directed DNA polymerase was made and a C-type virus-like particle was identified in platelets from 2 patients with the myeloproliferative disorder thrombocythemia (primary, essential, hemorrhagic, or idiopathic thrombocythemia). Platelet homogenates were centrifuged through a sucrose equilibrium density gradient. Both endogenous and exogenous DNA polymerase activity was found at a density of 1.19 g/ml. No activity was seen at comparable densities in control gradients. Electron micrographs of thin sections of these platelets revealed a particle with the morphologic characteristics of a C-type virus; however, the diameter of this particle was about 80 nm, slightly lower than that commonly found for C-type particles. Critical-point dried specimens, from the fractions of the sucrose gradient at which DNA polymerase activity was found, contained particles of the same size and morphology as those in the thin sections.
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PMID:Analysis of platelets from patients with thrombocythemia for reverse transcriptase and virus-like particles. 5 32

The influence of Rous sarcoma virus (RSV)-associated RNase H on the in vitro synthesis of DNA by the RSV RNA-directed DNA polymerase was determined under conditions whereby RNase H activity was selectively inhibited with NaF. Not only were we unable to detect any effect on the size, structure, or genetic complixity of the DNA product synthesized in the absence of RNase H activity, but the displacement of DNA from the 70S RNA:DNA hybrid structures was also unaffected. The suitability of 70S RNA:DNA hybrid structures synthesized in vitro to serve as a substrate for RNase H is discussed.
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PMID:In vitro transcription of 70S RNA by the RNA-directed DNA polymerase of Rouse sarcoma virus: lack of influence of RNase H. 5 43


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