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

---

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

Several analogues of 2',3'-dideoxythymidine 5'-triphosphate [i.e., 3'-azido-2', 3'-dideoxythymidine 5'-triphosphate(Azdd TTP), 2',3'-didehydro-2',3'-dideoxythymidine 5'-triphosphate (ddeTTP), alpha, beta-methylene 3'-azido-2',3'-dideoxythymidine 5'-diphosphate, alpha, beta-methylene 3'-azido-2',3'-dideoxythymidine 5'-triphosphate, and beta, gamma-methylene 3'-azido-2',3'-dideoxythymidine 5'-triphosphate] and 2',3'-didehydro-2',3'-dideoxycytidine 5'-triphosphate (ddeCTP) have been evaluated for their inhibitory effects on murine retroviral reverse transcriptase and various other DNA polymerases, including DNA polymerases alpha, beta, and gamma, terminal deoxynucleotidyl transferase, and DNA polymerase I. None of the compounds inhibited the activity of DNA polymerase alpha under the reaction conditions employed. When Mg2+ was replaced by Mn2+, however, DNA polymerase alpha was strongly inhibited only by ddeTTP. DNA polymerase beta activity was inhibited only by ddeTTP and ddeCTP. All the compounds, except for ddeCTP, inhibited DNA polymerase gamma activity, ddeTTP being a particularly strong inhibitor of gamma-polymerase (Ki = 3.5 nM). Terminal deoxynucleotidyl transferase was only slightly inhibited by any of the compounds. AzddTTP was a potent inhibitor of reverse transcriptase (Ki = 42 nM), but it also inhibited the activities of DNA polymerase gamma and DNA polymerase I.
...
PMID:Differential inhibitory effects of several pyrimidine 2',3'-dideoxynucleoside 5'-triphosphates on the activities of reverse transcriptase and various cellular DNA polymerases. 247 Oct 54

The reverse transcriptase from human immunodeficiency virus type 1 was purified from the virus to near homogeneity. The enzyme was shown to possess both RNA-dependent and DNA-dependent DNA-synthesizing activity. Activated DNA as a heteropolymeric substrate was used as efficiently as was the homopolymeric substrate poly(rA)-oligo(dT). The Michaelis-Menten constants were determined for each of the four nucleotides needed to elongate a natural template primer. Azidothymidine triphosphate, a well-known inhibitor of the enzyme, inhibited the enzyme competitively with respect to dTTP and noncompetitively with respect to the other nucleotides. Azidothymidine triphosphate acted as an efficient inhibitor of cellular DNA polymerase gamma, whereas other enzymes of eucaryotic DNA metabolism, namely, DNA polymerase alpha-primase and DNA polymerase beta, were not inhibited. This finding may explain why some acquired immunodeficiency syndrome patients suffer side effects during azidothymidine therapy.
...
PMID:Azidothymidine triphosphate is an inhibitor of both human immunodeficiency virus type 1 reverse transcriptase and DNA polymerase gamma. 248 2

A number of reports have suggested that platelets from polycythemia vera patients contain reverse transcriptase activity that might be correlated with C-type retrovirus-like particles. As described herein, we devised a new assay method for reverse transcriptase activity using MS-2 phage RNA hybridized with synthetic oligodeoxynucleotide (18-mer) as a template/primer. Using this new, sensitive assay method, we examined the platelet enzyme. By the conventional assay method using poly(rA)-oligo(dT), extracts of platelets showed a considerable amount of incorporation. However, by the new assay method using MS-2 RNA, no incorporation was observed. The poly(rA)-oligo(dT)-dependent activity was purified on Mono Q column, and it was shown that this activity coincided with that of DNA polymerase gamma.
...
PMID:Re-examination by improved reverse transcriptase assay of DNA polymerase in platelets from myelodysplastic disease patients. 248 74

5-(p-Chlorobenzyl)-6-aminouracil (5-ClAU) inhibited RNA-dependent DNA polymerase (reverse transcriptase) from avian myeloblastosis virus. Inhibition was expressed only in the presence of a polyribonucleotide template such as mRNA or poly(rA), and kinetic analysis suggested that the action of 5-ClAU is competitive with template:primer. 5-ClAU did not inhibit HeLa DNA polymerase gamma, an enzyme that efficiently copies polyribonucleotide templates. A mechanism is proposed in which a 5-ClAU:template complex interferes with enzyme function, based partly on NMR studies indicating that 5-ClAU can form a hydrogen-bonded complex with deoxyadenosine in solution.
...
PMID:Inhibition of RNA-directed DNA polymerase from avian myeloblastosis virus by a 5-benzyl-6-aminouracil. 257 88

Poly(2'-fluoro-2'-deoxyadenylic acid) (poly(dAfl)) and poly(2'-deoxycytidylic acid) (poly(dCfl)) were tested as templates in DNA synthesis reactions catalyzed by Xenopus laevis oocytes DNA polymerase alpha, mouse cell DNA polymerase gamma and avian myeloblastis virus (AMV) reverse transcriptase. Poly(dAfl).(dT)12 can fully substitute for poly(rA).(dT)12 as template with DNA polymerase gamma, to 50% with reverse transcriptase, but was poorly recognized by DNA polymerase alpha. DNA synthesis by reverse transcriptase with poly(dCfl).(dG)12 as template was 50% of that with poly(rC).(dG).(dG)12. The use of 2'-fluoropolymers as templates was more efficient at 37 degrees C than at 25 degrees C. No appreciable differences on the fidelity of DNA synthesis by reverse transcriptase were observed when dCMP misincorporation was measured with poly(dAfl).(dT)12 or poly(rA).(dT)12 as template primers. Poly(C) and poly-2'-O-methylcytidylic acid had no significant effect on the reaction catalyzed by DNA polymerase gamma and reverse transcriptase, independent of the synthetic polynucleotide complex utilized as template. On the other hand, poly(dCfl) was an inhibitor when poly(rA).(dT)12 or poly(dA).(dT)12 were used as templates, but not when poly(dAfl).(dT)12 was employed. Analogous results have been obtained with activated DNA and AMV 70 S RNA as templates in the reverse transcriptase reaction. The inhibition by poly(dCfl) was noncompetitive with regard to TTP, poly(dA) and poly(rA). Xenopus laevis oocytes DNA polymerase alpha was not inhibited by poly(dCfl).
...
PMID:2'-Fluoro-2'-deoxypolynucleotides as templates and inhibitors for RNA- and DNA-dependent DNA polymerases. 257 20

The diterpene ester promoter of mouse skin tumors, 12-O-tetradecanoylphorbol-13-acetate (TPA), efficiently induces Epstein-Barr virus (EBV)-associated DNA polymerase (DNA nucleotidyltransferase) activity in the EBV-producing lymphoblastoid cell line, P3HR-1. With the use of intervent dilution chromatography followed by sequential DEAE-cellulose and phosphocellulose column chromatography, the virus-associated enzyme has been isolated and purified 300-fold. The partially purified EBV DNA polymerase activity could be distinguished from cellular polymerases by its activation with salt and its degree of sensitivity to N-ethylmaleimide and phosphonoacetic acid. The enzyme showed maximum activity for copying activated calf thymus DNA in the presence of 100 mM ammonium sulfate. In the absence of salt, the enzyme utilized with high efficiency deoxyoligomer-homopolymer templates, but failed to copy poly(rA) . oligo(dT)10 and oligo(dT)10, showing that the enzyme had properties distinct from DNA polymerase gamma, reverse transcriptase, and terminal deoxynucleotidyltransferase. The partially purified enzyme is strongly inhibited by acyclovir triphosphate and thus has properties similar to herpes simplex virus DNA polymerase.
...
PMID:Induction of Epstein-Barr virus-associated DNA polymerase by 12-O-tetradecanoylphorbol-13-acetate. Purification and characterization. 624 99

Retrovirus particles with type C morphology were found in two T-cell lymphoblastoid cell lines, HUT 102 and CTCL-3, and in fresh peripheral blood lymphocytes obtained from a patient with a cutaneous T-cell lymphoma (mycosis fungoides). The cell lines continuously produce these viruses, which are collectively referred to as HTLV, strain CR(HTLV(CR)). Originally, the production of virus from HUT 102 cells required induction with 5-iodo-2'-deoxyuridine, but the cell line became a constitutive producer of virus at its 56th passage. Cell line CTCL-3 has been a constitutive producer of virus from its second passage in culture. Both mature and immature extracellular virus particles were seen in thin-section electron micrographs of fixed, pelleted cellular material; on occasion, typical type C budding virus particles were seen. No form of intracellular virus particle has been seen. Mature particles were 100-110 nm in diameter, consisted of an electron-dense core surrounded by an outer membrane separated by an electron-lucent region, banded at a density of 1.16 g/ml on a continuous 25-65% sucrose gradient, and contained 70S RNA and a DNA polymerase activity typical of viral reverse transcriptase (RT; RNA-dependent DNA nucleotidyltransferase). Under certain conditions of assay, HTLV(CR) RT showed cation preference for Mg(2+) over Mn(2+), distinct from the characteristics of cellular DNA polymerases purified from human lymphocytes and the RT from most type C viruses. Antibodies to cellular DNA polymerase gamma and anti-bodies against RT purified from several animal retroviruses failed to detectably interact with HTLV(CR) RT under conditions that were positive for the respective homologous DNA polymerase, demonstrating a lack of close relationship of HTLV(CR) RT to cellular DNA polymerases gamma or RT of these viruses. Six major proteins, with sizes of approximately 10,000, 13,000, 19,000, 24,000, 42,000, and 52,000 daltons, were apparent when doubly banded, disrupted HTLV(CR) particles were chromatographed on a NaDodSO(4)/polyacrylamide gel. The number of these particle-associated proteins is consistent with the expected proteins of a retrovirus, but the sizes of some are distinct from those of most known retroviruses of the primate subgroups.
...
PMID:Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma. 626 Dec 56

(-)-2'-deoxy-3'-thiacytidine (3TC) has been shown to be a potent, selective inhibitor of HIV replication in vitro, which requires phosphorylation to its 5'-triphosphate for antiviral activity. The intracellular concentration of 3TC 5'-triphosphate in phytohaemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PBL) shows a linear dependence on the extracellular concentration of 3TC up to an extracellular 3TC concentration of 10 microM. At this extracellular concentration of 3TC, the resulting intracellular concentration of 3TC 5'-triphosphate is 5 microM. This value is similar to the inhibition constant (Ki) values for the competitive inhibition of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and human DNA polymerases (10-16 microM) by 3TC 5'-triphosphate. Since the concentration of 3TC producing 90% inhibition (IC90) of HIV replication in PBLs has been reported to be 76 nM, the antiviral activity of 3TC requires intracellular concentrations of 3TC 5'-triphosphate, which would result in very little inhibition of reverse transcriptase if its sole mode of action was competitive inhibition. This apparent discrepency may be explained by the ability of 3TC 5'-triphosphate to act as a substrate for reverse transcriptase. Primer extension assays have shown that 3TC 5'-triphosphate is a substrate for HIV-1 reverse transcriptase and DNA polymerase gamma, resulting in the incorporation of 3TC 5'-monophosphate into DNA. In the case of DNA polymerase gamma, the product of this reaction (i.e. double-stranded DNA with 3TC 5'-monophosphate incorporated at the 3'-terminus of the primer strand) is also a substrate for the 3'-5' exonuclease activity of this enzyme. This may explain the low levels of mitochondrial toxicity observed with 3TC.
...
PMID:The intracellular phosphorylation of (-)-2'-deoxy-3'-thiacytidine (3TC) and the incorporation of 3TC 5'-monophosphate into DNA by HIV-1 reverse transcriptase and human DNA polymerase gamma. 757 60

Transfer RNA(Lys)SUU, with a 5-modified-2-thiouridine at wobble position 34, facilitates -1 frameshifts for correct translation of the Escherichia coli DNA polymerase gamma subunit and retroviral polymerases. Peptidyl-tRNA(Lys)SUU prematurely terminates translation more often than other tRNAs. In order to determine if the anticodon structures of bacterial and mammalian tRNA(Lys)SUU species explain these observations, oligonucleotides corresponding to the anticodon regions of mammalian and E. coli tRNA(Lys)SUU were synthesized and their physicochemical properties compared with that of E. coli tRNA(Glu)SUC. The anticodon region of tRNA(Lys)SUU was stabilized by an unusual interaction between the side chains of the 5-modified-s(2)U34 and N-6-threonylcarbamoyl-adenosine-37 (t(6)A37), a combination of modified nucleosides unique to tRNA(Lys)SUU species. This first observation of modified nucleoside side-chain interactions is analogous to the interactions of amino acid side chains in proteins. The tRNA(Lys)SUU anticodon structure was determined from NMR restraints on model oligonucleotides. With only two of three anticodon bases available for codon pairing, this unconventional anticodon structure is a reasonable explanation for the bacterial and mammalian tRNA(Lys)SUU tendency to frameshift. A two-out-of-three reading of coding triplets also explains the increased rate at which peptidyl-tRNA(Lys)SUU prematurely terminates translation. In addition, modified nucleoside interaction distorts the anticodon loop. The distorted loop is a possible structural determinant for the preferential selection of tRNA(Lys3)SUU as primer of HIV-1 reverse transcriptase in vivo.
...
PMID:Unconventional structure of tRNA(Lys)SUU anticodon explains tRNA's role in bacterial and mammalian ribosomal frameshifting and primer selection by HIV-1. 908 48

(-)-beta-D-2,6-Diaminopurine dioxolane (DAPD), is a nucleoside reverse transcriptase (RT) inhibitor with activity against human immunodeficiency virus type 1 (HIV-1). DAPD, which was designed as a water-soluble prodrug, is deaminated by adenosine deaminase to give (-)-beta-D-dioxolane guanine (DXG). By using calf adenosine deaminase a K(m) value of 15 +/- 0.7 microM was determined for DAPD, which was similar to the K(m) value for adenosine. However, the k(cat) for DAPD was 540-fold slower than the k(cat) for adenosine. In CEM cells and peripheral blood mononuclear cells exposed to DAPD or DXG, only the 5'-triphosphate of DXG (DXG-TP) was detected. DXG-TP is a potent alternative substrate inhibitor of HIV-1 RT. Rapid transient kinetic studies show the efficiency of incorporation for DXG-TP to be lower than that measured for the natural substrate, 2'-deoxyguanosine 5'-triphosphate. DXG-TP is a weak inhibitor of human DNA polymerases alpha and beta. Against the large subunit of human DNA polymerase gamma a K(i) value of 4.3 +/- 0.4 microM was determined for DXG-TP. DXG showed little or no cytotoxicity and no mitochondrial toxicity at the concentrations tested.
...
PMID:Mechanism of action of 1-beta-D-2,6-diaminopurine dioxolane, a prodrug of the human immunodeficiency virus type 1 inhibitor 1-beta-D-dioxolane guanosine. 1112 Sep 59


<< Previous 1 2 3 4 Next >>

---