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)

Several cholic acid derivatives such as taurolithocholic acid, lithocholic acid 3-sulfate, taurolithocholic acid 3-sulfate, and glycolithocholic acid 3-sulfate were shown to inhibit selectively the replication of human immunodeficiency virus type 1 (HIV-1) in vitro. These compounds completely protected MT-4 cells against HIV-1-induced cytopathogenicity at a concentration of 100 micrograms/ml, whereas no toxicity for the host cells was observed at 200 micrograms/ml. They also inhibited HIV-1 antigen expression in HIV-1-infected CEM cells. The bile acids (cholic acid, deoxycholic acid, chenodeoxycholic acid, and lithocholic acid) did not show any inhibitory effect on HIV-1 replication at concentrations that were not toxic to the host (MT-4) cells. From a structure-function analysis of a number of cholic acid derivatives, the presence of either a sulfonate (as in the tauro conjugates) or a sulfate group as well as the "litho" configuration appeared to be necessary for the expression of anti-HIV-1 activity. The active cholic acid derivatives did not directly inactivate the virus particles at the concentrations that were not toxic to the host cells. Lithocholic acid 3-sulfate, taurolithocholic acid 3-sulfate, and glycolithocholic acid 3-sulfate, but not taurolithocholic acid, partially inhibited virus adsorption to MT-4 cells. These three compounds were also inhibitory to the reverse transcriptase activity associated with HIV-1.
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PMID:Selective activity of several cholic acid derivatives against human immunodeficiency virus replication in vitro. 230 4

Fucoidan and dextran sulfate showed anti-HIV activities against mononuclear cells from AIDS patients, and they abrogated HIV reverse transcriptase (RT) activity by interacting with the HIV envelope in the membranes of target cells. Furthermore, they showed a synergistic effect with azidothymidine (AZT).
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PMID:Further characterization of sulfated homopolysaccharides as anti-HIV agents. 247 88

A sulfate (GE-3-S) prepared by chlorosulfonic acid treatment of GE-3, a partially acetylated beta(1----6) glucan of the lichen Umbilicaria esculenta, inhibited the cytopathic effect of human immunodeficiency virus (HIV) and suppressed the HIV-antigen expression in Molt-4 (clone 8) cells. GE-3-S also suppressed the giant cell formation of HIV-infected Molt-4 cells, and inhibited HIV-induced plaque formation by 50% at the dose of 19.5 micrograms/ml and completely at 250 micrograms/ml in MT4 cells. GE-3-S had no direct effect on the reverse transcriptase of HIV.
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PMID:Inhibitory effect of a lichen polysaccharide sulfate, GE-3-S, on the replication of human immunodeficiency virus (HIV) in vitro. 257 16

We reported previously that homopolysaccharides with sulfate groups revealed immunomodulating activities--lymphocyte mitogens. We further investigated the role of homopolysaccharides in a different system--cultivation of Molt-4. clone no.8 with supernatant from human T cell lymphotropic virus type III (HTLV-III)-infected TALL-1, utilizing cytopathic effects (CPE), fluorescence antibody technique (FAT), reverse transcriptase (RT) assay and cell proliferation assay. Sulfated homopolysaccharides such as fucoidan, dextran sulfate with three different molecular weights, cellulose sulfate and k-carrageenan showed most potent anti-HTLV-III activities at mitogenic doses. However, neutral homopolysaccharides had no effects on anti-HTLV-III activities Sulfated heteropolysaccharides such a heparin and heparan sulfate had a little effect on anti-HTLV-III activities. It is suggested that sulfate group is most important in inhibiting growth of HTLV-III, but the structure of the polysaccharides is also important, because homopolysaccharides are more potent anti-HTLV-III agents than heteropolysaccharides.
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PMID:Sulfated homopolysaccharides with immunomodulating activities are more potent anti-HTLV-III agents than sulfated heteropolysaccharides. 290 62

Several steps in the replicative cycle of human immunodeficiency virus (HIV) could be envisaged as targets for anti-AIDS drugs. The anionic compound PMEA [9-(2-phosphonyl-methoxyethyl)adenine], the 2'3'-dideoxynucleoside analogues D4T (2',3-deidehydro-2',3'-dideoxythymidine), AzddUrd 3'-azido-2',3'-dideoxyuridine), FddUrd (3'-fluoro-2',3-dideoxyuridine), AzddDAPR (3'-azido-2',3'-dideoxy-2,6' diaminopurine riboside) and the sulfated polysaccharides dextran sulfate and pentosan polysulfate are among the most promising candidate anit-AIDS drugs which have been recently described. They are targeted at either virus-cell binding (dextran sulfate, pentosan polysulfate) or virus-associated reverse transcriptase (PMEA, D4T, AzddUrd, FddUrd, AzddDAPR).
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PMID:Perspectives for the chemotherapy of AIDS. 290 40

In the design of selective inhibitors of the human immunodeficiency virus (HIV), the etiologic agent of AIDS, various steps of the virus replicative cycle could be envisaged as targets, i.e. virus adsorption to its cellular receptor (or another early event in virus replication such as penetration or uncoating), transcription of the viral RNA genome to proviral DNA (reverse transcription), trans-activation of viral mRNA transcription and translation, and, finally, virus release ("budding", or another late event in virus replication such as the assembly process). Although some potent HIV inhibitors such as heparin and dextran sulfate may interfere with an early step of the virus replicative cycle (adsorption) and others (interferon and interferon inducers) are assumed to act at a late step (budding), the majority of the anti-HIV agents appear to act at the reverse transcriptase level. Most of these reverse transcriptase inhibitors belong to the class of the 2',3'-dideoxynucleosides (ddN), and within this class of compounds a variety of 2',3'-dideoxy-, 2',3'-didehydro-2',3'-dideoxy-, 3'-azido-2',3'-dideoxy- and 3'-fluoro-2',3'-dideoxyribosides of both purines and pyrimidines have been described as potent and selective anti-HIV agents. Akin to 3'-azido-2',3'-dideoxythymidine (AZT), the sole anti-HIV compound that has so far been licensed for clinical use in the treatment of AIDS, all other ddN analogues are postulated to interact as competitive inhibitors (with respect to the natural substrates) and/or chain terminators of the HIV reverse transcriptase. To do so, the ddN analogues need first to be phosphorylated by cellular kinases to the corresponding 5'-triphosphates (ddNTPs), and together with the affinity of the ddNTPs for the HIV reverse transcriptase (relative to their affinity for the cellular DNA polymerases), the extent by which the ddNs are phosphorylated to the ddNTPs are critical determinants of their potency and selectivity as anti-HIV agents. Much more remains to be learned about the in vivo efficacy of the 2',3'-dideoxynucleoside analogues, and their pharmacokinetic and toxicological properties, before their true potential in the treatment of AIDS can be fully assessed.
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PMID:Perspectives for the chemotherapy of AIDS. 332 34

The location of unpaired adenine residues within the secondary structure of rabbit 18S ribosomal RNA was determined by chemical probing. Naked 18S rRNA was first prepared by digestion of purified 40S subunits with matrix-bound proteinase K in sodium dodecyl sulfate, thereby omitting the use of nucleic acid denaturants. Adenines within naked 18S rRNA were chemically probed by using either diethyl pyrocarbonate or dimethyl sulfate, which specifically react with unpaired nucleotides [Peattie, D. A., & Gilbert, W. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 4679-4682]. Adenine modification sites were identified by polyacrylamide sequencing gel electrophoresis either upon aniline-induced strand scission of 32P-end-labeled intact and fragmented rRNA or by primer extension using sequence-specific DNA oligomers with reverse transcriptase. The data indicate good agreement between the general pattern of adenine reactivity and the location of unpaired regions in 18S rRNA determined by comparative sequence analysis [Chan, Y.-L., Gutell, R., Noller, H. F., & Wool, I. G. (1984) J. Biol. Chem. 259, 224-230]. The overall reactivity of adenine residues toward single-strand-specific chemical probes was, also, similar for both rabbit and Escherichia coli small rRNA. The number of strongly reactive adenines appearing within phylogenetically determined helical segments, however, was greater in rabbit 18S rRNA than for E. coli 16S rRNA. Some of these adenines were found clustered in specific helices. Such differences suggest a greater irregularity of many of the helical elements within mammalian 18S rRNA, as compared with prokaryotic 16S rRNA. These helical irregularities could be important for protein association and also may represent biologically relevant flexible regions of the molecule.
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PMID:Chemical probing of adenine residues within the secondary structure of rabbit 18S ribosomal RNA. 334 49

We have determined the complete nucleotide (nt) sequence of a 2937-bp DNA fragment containing the yeast maltase (EC 3.2.1.20) gene (MAL6S) as well as part of the contiguous maltose permease gene (MAL6T) from the MAL6 locus of Saccharomyces carlsbergensis. The MAL6S gene encodes an alpha-glucosidase that is required for the utilization of maltose as a carbon source by yeast. The 5' transcription initiation sites for both MAL6S and MAL6T were determined by primer extension experiments using reverse transcriptase. The sequence data show one major open reading frame (ORF) of 584 amino acids (aa) for maltase with a calculated Mr of 68 107, somewhat larger than the value of 63 000 previously determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) analysis. The nucleotide sequences upstream of both the MAL6S and MAL6T genes, which are divergently transcribed, show common structural features for the transcription initiation of yeast genes as well as signals required for their translation. The codon bias index shows that the MAL6S gene is moderately expressed. The possible significance of two 17-bp dyad symmetric sequences, found in the intergenic region of MAL6S and MAL6T, for the control of expression of these genes is also discussed.
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PMID:Primary structure of the maltase gene of the MAL6 locus of Saccharomyces carlsbergensis. 351 95

Two structurally distinct forms of RNA-directed DNA polymerase from avian myeloblastosis virus were resolved by chromatography on phosphocellulose and purified. In addition to RNA-directed DNA polymerase activity, both enzymes had ribonuclease H (RNase H) activity, which degraded the RNA moiety of RNA.DNA hybrids. As determined by sodium dodecyl sulfate-polyacrylamide disc-gel electrophoresis, one form had two subunits, alpha (alpha) and beta (beta), with molecular weights of 65,000 and 105,000, respectively. The other had a single subunit, alpha, with a molecular weight of 65,000. The sedimentation coefficients of alphabeta and alpha, determined by glycerol gradient centrifugation in 0.35 M KCl, were 7.8 S and 5.2 S, respectively. Both enzymes had similar antigenic determinants and could not be distinguished by a differential response to several different RNA and DNA templates. We suggest that alpha, which contains both RNA-directed DNA polymerase and RNase H activity, is derived by dissociation of alphabeta; the function of the beta subunit is unknown.
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PMID:A single subunit from avian myeloblastosis virus with both RNA-directed DNA polymerase and ribonuclease H activity. 411 23

The 14S messenger RNA, which contains poly(adenylic acid), of MOPC 41 (mouse plasmocytoma) immunoglobulin light chain, purified to a single peak as shown by polyacrylamide gel electrophoresis, was used to synthesize complementary DNA with the RNA-dependent DNA polymerase of avian myeloblastosis virus. DNA synthesis is entirely dependent on added RNA template and oligo(dT) primer. Both the size and the concentration of the primer affect the reaction. The product behaves similarly to DNA during centrifugation in cesium sulfate density gradients. It is shown by hybridization that the DNA made is complementary to the purified template, light-chain mRNA. The high specific activity of the complementary DNA should make it suitable for gene-dosage experiments. According to alkaline sucrose gradient analyses, some complete complementary DNA transcripts of the 14S mRNA seem to be made. Oligo(dG) can also function as a primer for DNA synthesis, possibly by annealing to an internal cluster of cytidines in the mRNA, that correspond to the bases coding for amino-acids 119 and 120 of the MOPC 41 light chain.
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PMID:Enzymatic synthesis of DNA complementary to purified 14S messenger RNA of immunoglobulin light chain. 412 88


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