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)

Analogues of 2',5'-oligoadenylates (2-5A), the cordycepin (3'-deoxyadenosine) core trimer (Co3) and its 5'-monophosphate derivative (pCo3), were shown to display pronounced anti-human immunodeficiency virus type 1 (HIV-1) activity in vitro. Treatment of HIV-1 infected H9 cells with 1 microM Co3 or pCo3 resulted in an almost 100% inhibition of virus production. The compounds were encapsulated in liposomes targeted by antibodies specific for the T-cell receptor molecule CD3. Substitution of one or two cordycepin units in Co3 or pCo3 decreased the antiviral activity of the compounds. pCo3 did not stimulate 2-5A-dependent ribonuclease L activity and displayed no effect on the amount of cellular RNA and protein. At a concentration of 10 microM the cellular DNA polymerases alpha, beta, and gamma were almost insensitive toward Co3 or pCo3. In contrast, these compounds reduced the activity of HIV-1 reverse transcriptase (RT) by 90% at a concentration of 10 microM if the viral RNA genome and the cellular tRNALys.3 was used as template/primer system; if the synthetic poly(A).(dT)10 was used as template/primer, no marked inhibition was observed. Dot-blot, gel-retardation, and cross-linking assays showed that Co3 or pCo3 interfere with the binding site of tRNALys.3 to RT. These results indicate that inhibition of RT at the level of initiation of the enzymic reaction is a novel approach to inhibit HIV-1 replication.
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PMID:Cordycepin analogues of 2',5'-oligoadenylate inhibit human immunodeficiency virus infection via inhibition of reverse transcriptase. 170 37

Several different nucleoside analogs have been demonstrated to inhibit retroviral RNA-dependent DNA polymerase activity in preference to cellular DNA-dependent DNA polymerases. 3'-Amino derivatives of 3-deoxyadenosine was analyzed for their antiviral activity toward HIV-1 and for their host cell toxicity. Puromycin aminonucleoside (PANS), PANS 5'-monophosphate, and 3'-amino-3'-deoxyadenosine triphosphate all inhibited HIV-1 replication in acutely infected cells. No significant antiviral effects of PANS were demonstrated in chronically infected cells. The effect of PANS was demonstrated at an early step in HIV-1 replication, most likely reverse transcription. 3'-Aminonucleoside analogs are a novel class of inhibitors of HIV-1 replication that require further analysis in cell culture and animal studies.
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PMID:Analogs of 3'-amino-3'-deoxyadenosine inhibit HIV-1 replication. 261 Oct 44

2-Chloro-3'-deoxyadenosine (2-chlorocordycepin), 2-chloro-2',3'-dideoxyadenosine (2-ClddAdo), and 2-chloro-2',3'-didehydro-2',3'-dideoxyadenosine (2-ClddeAdo) were synthesized from 2-chloroadenosine (2-ClAdo) as candidate antiretroviral agents on the basis that 2-chloro substitution would prevent enzymatic deamination and increase efficacy relative to 2',3'-dideoxyadenosine (ddAdo). Reduction of 2-chloro-5'-(4,4'-dimethoxytrityl)-2',3'-O-thiocarbonyladenosine with n-Bu3SnH, followed by detritylation with AcOH, unexpectedly gave a mixture of 2-chlorocordycepin and 2-chloroadenine. Treatment of the crude n-Bu3SnH reduction product with 1,1'-thiocarbonyldiimidazole, followed by another cycle of n-Bu3SnH reduction and detritylation with silica gel afforded 2-ClddAdo and a byproduct identified as 2-chloro-2',3'-O-methyleneadenosine. Treatment of 2-chloro-5'-O-(4,4'-dimethoxytrityl)-2',3'-thiocarbonyladenosine with 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine followed by silica gel detritylation afforded 2-ClddeAdo. 2-ClddAdo and 2-ClddeAdo were tested for activity against human immunodeficiency virus (HIV) in a cultured human T4+ lymphocyte cell line. At a concentration of 100 microM, 2-ClddAdo inhibited reverse transcriptase (RT) production by 97%, while 2',3'-dideoxyadenosine (ddAdo) gave greater than 99% inhibition. In growth assays against uninfected T4+ cells, however, 100 microM 2-ClddAdo gave 23% inhibition while 100 microM ddAdo was nontoxic. At a nontoxic concentration of 20 microM, RT production was 75% inhibited by ddAdo but only 43% inhibited by 2-ClddAdo. Thus, a 2-chloro substituent increased host cell toxicity but decreased antiretroviral activity. The unsaturated analogue 2-ClddeAdo was more cytotoxic than 2-ClddAdo, and antiviral effects could not be measured above 20 microM, where there was only 75% inhibition of RT production. Because of the decreased therapeutic index of 2-ClddeAdo relative to 2-ClddAdo and ddAdo, greater than 90% inhibition of viral protein synthesis at a noncytotoxic concentration could not be achieved. In growth assays with cultured human T and B lymphocytes, 100 microM 2-chlorocordycepin gave 60-70% growth inhibition, while the IC50 against mouse fibroblasts was only 30 microM. The high cytotoxicity of 2-chlorocordycepin precluded consideration of this compound as an antiviral agent.
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PMID:Synthesis of the 2-chloro analogues of 3'-deoxyadenosine, 2',3'-dideoxyadenosine, and 2',3'-didehydro-2',3'-dideoxyadenosine as potential antiviral agents. 278 12

It has not been unambiguously demonstrated whether the priming reaction of human immunodeficiency virus, type 1 (HIV-1) cDNA synthesis initiates with either the 2'-OH or 3'-OH group of the 3'-terminal adenosine residue of tRNA(Lys-3). In this report, we synthesized tRNA(Lys-3) of which the 3'-terminal adenosine residue lacks either a 2'-OH or 3'-OH. These tRNA molecules were used for the HIV-1 cDNA-priming reaction in a cell-free system consisting of a 141-base RNA template and purified HIV-1 reverse transcriptase. It was found that under the conditions used, the tRNA containing the 2'-deoxyadenosine was able to initiate the cDNA synthesis, while the tRNA with the 3'-deoxyadenosine was not. The results show that retroviral reverse transcriptase specifically primes cDNA synthesis from the 3'-OH group. This is in contrast to bacterial reverse transcriptase, which initiates cDNA synthesis from the 2'-OH group of an internal guanosine residue of a template RNA.
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PMID:Specificity of priming reaction of HIV-1 reverse transcriptase, 2'-OH or 3'-OH. 750 35

DNA polymerase photoprobes 2-[(4-azidophenacyl)thio]-2'-deoxyadenosine 5'-triphosphate (1), 2-[(4-azidophenylsulfenyl)thio]-2'-deoxyadenosine 5'-triphosphate (2), and 2-[(4-azido-2-nitrophenyl)-thio]-2'-deoxyadenosine 5'-triphosphate (3) were designed from a thermodynamic model of DNA polymerase 1-substrate interactions such that the triphosphate would anchor the inhibitor and allow the phenyl azide to interact with the complementary template binding site. Photoprobes 1-3 were synthesized by condensation of 2-thio-2'-deoxyadenosine or its phosphate with p-azidophenacyl bromide, N-(4-azidophenylsulfenyl)phthalimide, and 4-azido-1-fluoro-2-nitrobenzene, respectively, and characterized as reversible and photoinduced irreversible inhibitors of the DNA polymerase I Klenow fragment and HIV I reverse transcriptase. The aryl azides decomposed with irradiation at 300 and 350 nm with half-lives ranging from 0.98 to 2.33 min and 2.15 to 5.38 min, respectively, with quantum efficiencies ranging from 0.29 to 0.55 and no apparent photodecomposition of the 2-thio-2'-deoxyadenosine nucleotide. Photoprobes 1-3 showed mixed noncompetitive inhibition of the Klenow fragment polymerase activity versus poly(dA).(T)10 as variable substrate with apparent competitive inhibition constants of 2.1, 36, and 29 microM, respectively, evidence suggesting that these photoprobes bind to both the free enzyme form and the enzyme-template-primer binary complex. Of the three photoprobes, only nucleotide 1 photoinactivates the Klenow fragment; in the presence of a 200-fold excess of nitrene scavenger, photoprobe 1 inactivates 92% of the Klenow fragment polymerase activity with saturation observed at 9.7 microM and an IC50 of about 2 microM. This evidence demonstrates that photoprobe 1 does bind to the Klenow fragment in the absence of template-primer and that it is an efficient photoprobe.
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PMID:Deoxyadenosine-based DNA polymerase photoprobes: design, synthesis, and characterization as inhibitors of the Escherichia coli DNA polymerase I Klenow fragment. 879 43

A series of 4'-ethynyl (4'-E) nucleoside analogs were designed, synthesized, and identified as being active against a wide spectrum of human immunodeficiency viruses (HIV), including a variety of laboratory strains of HIV-1, HIV-2, and primary clinical HIV-1 isolates. Among such analogs examined, 4'-E-2'-deoxycytidine (4'-E-dC), 4'-E-2'-deoxyadenosine (4'-E-dA), 4'-E-2'-deoxyribofuranosyl-2,6-diaminopurine, and 4'-E-2'-deoxyguanosine were the most potent and blocked HIV-1 replication with 50% effective concentrations ranging from 0.0003 to 0.01 microM in vitro with favorable cellular toxicity profiles (selectivity indices ranging 458 to 2,600). These 4'-E analogs also suppressed replication of various drug-resistant HIV-1 clones, including HIV-1(M41L/T215Y), HIV-1(K65R), HIV-1(L74V), HIV-1(M41L/T69S-S-G/T215Y), and HIV-1(A62V/V75I/F77L/F116Y/Q151M). Moreover, these analogs inhibited the replication of multidrug-resistant clinical HIV-1 strains carrying a variety of drug resistance-related amino acid substitutions isolated from HIV-1-infected individuals for whom 10 or 11 different anti-HIV-1 agents had failed. The 4'-E analogs also blocked the replication of a non-nucleoside reverse transcriptase inhibitor-resistant clone, HIV-1(Y181C), and showed an HIV-1 inhibition profile similar to that of zidovudine in time-of-drug-addition assays. The antiviral activity of 4'-E-thymidine and 4'-E-dC was blocked by the addition of thymidine and 2'-deoxycytidine, respectively, while that of 4'-E-dA was not affected by 2'-deoxyadenosine, similar to the antiviral activity reversion feature of 2',3'-dideoxynucleosides, strongly suggesting that 4'-E analogs belong to the family of nucleoside reverse transcriptase inhibitors. Further development of 4'-E analogs as potential therapeutics for infection with multidrug-resistant HIV-1 is warranted.
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PMID:4'-Ethynyl nucleoside analogs: potent inhibitors of multidrug-resistant human immunodeficiency virus variants in vitro. 1130 24

We report the design, synthesis and activity studies on a novel class of template-competitive reverse transcriptase inhibitors (TCRTIs). The TCRTIs are 1,N(6)-etheno analogues of a series of dATP-based template-competitive DNA polymerase inhibitors synthesized in our laboratory (Moore, B. M.; Jalluri, R.; Doughty, M.B. Biochemistry 1996, 35, 11634). Thus, nucleotides 2-(4-azidophenacyl)thio-1,N(6)-etheno-2'-deoxyadenosine 5'-triphosphate 1, the tetrafluoro analogue 2-(4-azido-2,3,5,6-tetrafluorophenacyl)thio-1,N(6)-etheno-2'-deoxyadenosine 5'-triphosphate 2 and its analogues were synthesized by alkylation of 2-thio-1,N(6)-etheno-2'-deoxyadenosine 5'-monophosphate with the corresponding chloro- or bromo-alkyl halides and converted to the triphosphate. Kinetically, nucleotides 1 and 2 are both competitive inhibitors of reverse transcriptase versus template/primer with K(i)'s of 8.0 and 7.4 microM, respectively, and non-competitive inhibitors versus TTP with K(i)'s of 15 and 10 microM, respectively. Nucleotide 3, which differs from 1 only in that it lacks the etheno group, non-complementary nucleotide triphosphates, and related monophosphates and nucleosides, are completely inactive as inhibitors of reverse transcriptase at concentrations up to 1 mM. Photoinactivation of RT by 1 was both time- and concentration-dependent, and protected by template/primer but not by dNTPs. The concentration-dependent inactivation data gave a K(D,app) of 17.2 microM and maximum inactivation of 90%, and radiolabeled [beta, gamma-32P]-1 photoincorporated specifically and covalently into the p66 subunit of RT. Thus the photoinactivation data support our main conclusion from the kinetic data that this class of RT inhibitors are non-substrate and template-competitive.
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PMID:Template-competitive inhibitors of HIV-1 reverse transcriptase: design, synthesis and inhibitory activity. 1181 36

Analogues of a novel class of template-competitive reverse transcriptase inhibitors (Li, K.; Lin, W.; Chong, K. H.; Moore, B. M.; Doughty, M. B. Bioorg. Med. Chem. 2002, 10, 507) were analyzed as photoprobes of HIV-1 reverse transcriptase (RT) heterodimer. The two photoprobes, 2-(4-azidophenacyl)thio-1,N(6)-etheno-2'-deoxyadenosine 5'-triphosphate 2 and the tetrafluoro analogue 2-(4-azido-2,3,5,6-tetrafluorophenacyl)thio-1,N(6)-etheno-2'-deoxyadenosine 5'-triphosphate 3, photodecomposed at 3500 A with half-lives of 4.0 and 2.5 min, respectively. Analysis of the photoproducts of 2m demonstrated that the etheno group is stable but the azido decomposes primarily to the 2-(S-[3H-diazepinon-4-yl]thio)-1,N(6)-etheno-dAMP. Photolysis of both 2 and 3 with RT resulted in a time-dependent loss of activity, with maximum inactivation of 83 and 60%, respectively. Both 2 and 3 showed concentration-dependent photoinactivation of RT in the concentration range from 0 to 100 microM, with EC(50)s of 20 and 25 microM and maximum inactivation of 80 and 60%, respectively. Both the time and concentration dependent photoinactivation were strongly protected by template-primer, but only poorly inhibited by even high concentrations of TTP. Radiolabeled analogues [beta,gamma-(32)P]-2 and [beta,gamma-(32)P]-3 photoincorporated into the p66 subunit, an incorporation also protected by template primer. Identification of the site of incorporation was problematic for both photoprobes, but evidence presented is consistent with labeling sites for the phenacyl side chains of both 2 and 3 in the template grip. Nevertheless, the photoinactivation and incorporation data are consistent with our earlier conclusions from the kinetic data that these inhibitors are specific for the free form of RT in competition with template/primer, and thus represent a novel class of inhibitors.
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PMID:Characterization of a binding site for template competitive inhibitors of HIV-1 reverse transcriptase using photolabeling derivatives. 1241 67

In the past years, a variety of 4'-C-substituted-2'-deoxynucleosides (4'SdNs) were designed, synthesized, and examined as potential therapeutics against human immunodeficiency virus (HIV) infection and certain such analogues proved to exert potent activity against HIV-1 in vitro. Unlike currently available nucleoside reverse transcriptase (RT) inhibitors such as 3'-azido-3'-deoxythymidine (AZT), which have the 2',3'-dideoxy configuration and thereby cause DNA chain termination in the elongating proviral DNA, 4'SdNs do retain the 3'-alpha-OH moiety but also appear to work against retrovirus as proviral DNA chain terminators. Several 4'SdNs have been shown to be active against various laboratory and clinical HIV-1 strains including known drug-resistant HIV-1 variants. Among such 4'SdNs is 4'-azido-2'-deoxythymidine (4'-AZT) which exerts potent antiviral activity against wild type and AZT-resistant clinical HIV strains. More anti-HIV 4'SdNs have recently been reported including 4'-ethynylthymidine, 4'-ethynyl-2'-deoxy-D-ribofuranosyl-2,6-diaminopurine (4'-E-dDAP), 4'-ethynyl-2'-deoxyguanosine (4'-E-dG) and 4'-ethynyl-2'-deoxyadenosine (4'-E-dA). The latter three analogues are highly potent against HIV-1 and HIV-2 with EC50 values ranging from 0.0003 to 0.01 microM and have favorable cytotoxicity profiles with selective index (SI) values ranging from 975 to 2600. These 4'-ethynyl-2'-deoxynucleosides also exert potent activity against all known drug-resistant HIV-1 variants including the multi-dideoxynucleoside-resistant HIV and the variants with the 6-base pair inserts. Some of these compounds have favorable pharmacological properties and further development as potential therapeutics against HIV-1 infection is warranted.
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PMID:4'-C-substituted-2'-deoxynucleosides: a family of antiretroviral agents which are potent against drug-resistant HIV variants. 1245 29

Nucleotides 2-(4-azidophenacyl)thio-1,N6-etheno-2'-deoxyadenosine 5'-triphosphate 1 and its tetrafluoro analog 2 inhibit HIV-1 reverse transcriptase (RT) competitively relative to template. These template-competitive RT inhibitors (TCRTIs) were analyzed for conformational properties by molecular modeling and NMR analysis. Both inhibitors prefer sugar conformations of C2'-endo/C3'-exo with a high-anti glycosidic bond rotation and +sc/ap phosphate conformation (gamma). The major effect of the etheno group is to favor an extended, fully staggered anti conformation in the N1-C2-S-CH2 psi1 side chain rotation, and NMR analysis detects a long range sugar H4' to side chain phenyl meta-H NOE, a result consistent with this compact structure as an important contributor to the solution structure. The binding model generated places the phenyl side chain in a lipophilic pocket in the template grip region of the RT polymerase domain with the Mg-triphosphate complexed to active site carboxylates. The structures of the TCRTIs are compared with that of the template-competitive DNA polymerase inhibitor 2-(4-azidophenacyl)thio-2'-deoxyadenosine 5'-triphosphate 3, and a theoretical model for selectivity is proposed.
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PMID:Conformational properties of nucleotide-based template-competitive HIV-1 reverse transcriptase inhibitors: analysis of enzyme binding modes. 1281 87


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