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)

Procedures were established for the isolation and partial purification of DNA polymerase, RNA polymerase and poly(A) polymerase activities from the cytoplasm and nuclei of NIH-Swiss mouse embryos. Based on the elution pattern of these enzyme activities from DEAE-cellulose and phosphocellulose columns in Tris-HCl buffer, pH 8.0, the apparent basicities of the enzymes can be arranged as follows: cytoplasmic(C) poly(A) polymerase greater than (C)DNA polymerase beta greater than (C)DNA polymerase alpha and nuclear(N) poly(A) polymerase greater than (N)DNA polymerase greater than (N)RNA polymerase I greater than (N)RNA polymerase II. Twenty rifamycins, including rifamycin B, rifamycin S, rifamycin SV, and rifamycin SV derivatives, were examined for their ability to inhibit the above mentioned nucleic acid polymerizing enzymes and Simian sarcoma virus type I (SSV-1) reverse transcriptase. Rifamycin SV 3'-formyldiphenylhydrazone, rifamycin SV 3'-formyl-n-octyloxime (AF/013) and rifamycin SV 3'-formyldiphenylmethyloxime (AF/05) inhibited all the tested enzyme activities. Rifamycin SV 3'-formylpropylphenyloxime (AF/015) inhibited cellular nucleic acid polymerase activities but not SSV-1 DNA polymerase activity. Rifamycin SV 3'-formyldinitrophenylhydrazone (AF/DNFL) strongly inhibited reverse transcriptase activity but did not inhibit cellular DNA polymerase activities. AF/DNFI slightly inhibited RNA and poly(A) polymerase activities. Rifamycin SV 3'-formyldipropylhydrazone (AF/DPI) and 2,6-dimethyl-4-N-benzyldemethyl-rifampicin (AF/ABDMP) slightly inhibited reverse transcriptase activity but did not inhibit cellular nucleic acid polymerase activities. Active rifamycin derivatives inhibited enzyme reactions by interacting with the enzyme proteins. Nascent polynucleotide chain elongation continued although at a reduced rate in the presence of inhibitor. The addition of increasing concentrations of nonionic detergent (Triton X-100) to rifamycin-inhibited enzyme reactions fully restored enzyme activities. The presence of highly lipophilic 3'-side chains on active rifamycins and the reversibility of enzyme inhibition by Triton X-100 suggest that the tested nucleic acid polymerizing enzymes may have hydrophobic regions with which inhibitory rifamycins interact.
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PMID:Interaction of rifamycins with mammalian nucleic acid polymerizing enzymes. 6 93

DNA complementary to ovalbumin mRNA and covalently bound to cellulose (cDNA-cellulose) was synthesized using avian myeloblastosis virus RNA-directed DNA polymerase. High concentrations of actinomycin D (200 migrogram/ml) were required to produce 97% inhibition of double-stranded DNA synthesis, but mRNA transcription was only slightly inhibited (14%). The conditions used for binding of mRNA to cDNA-cellulose permitted complete hybridization of ovalbumin mRNA in 10 min while stable poly(A):(dT) hybrids failed to form. The temperature at which 50% of the ovalbumin mRNA activity was eluted from cDNA-cellulose was 62 degrees in 0.01 M Tris.HCl. When a batchwise procedure of hybridization and elution was used, the total recovery of ovalbumin mRNA activity applied to the cDNA-cellulose was greater than 98%, indicating little if any degradation of mRNA. Ovalbumin mRNA activity eluted in each chromatographic run was 50 to 70% of that originally used for the synthesis of the cDNA-cellulose. When total polysomal RNA was subjected to chromatography, the bound fraction consisted of ovalbumin mRNA, rRNA, and material behaving like fragments of ovalbumin mRNA. Applying this fraction to cDNA-cellulose a second time eliminated the rRNA but not the presumptive fragments. Ovalbumin mRNA purified either once or twice was enriched between 43- and 56-fold over polysomal RNA in translational activity.
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PMID:Chromatography of ovalbumin messenger ribonucleic acid on complementary deoxyribonucleic acid-cellulose. 7 8

The use of exclusionary techniques in the procurement of donors for bone allografts greatly reduces chances for disease transmission. Furthermore, treatment of HIV with either chemical agents or strong acids will effectively inactivate the AIDS virus. These data are taken as indirect proof that the risk of obtaining AIDS from a freeze-dried bone allograft is highly remote. The purpose of this study is to obtain direct evidence that the processing of a demineralized freeze-dried bone allograft would render the allograft safe for human use. In Part I, human cortical bone was obtained from a cadaveric source and tested to be free of HIV contamination. The bone was spiked with 5.26 x 10(9) viral particles. This corresponded to 148 micrograms of total viral protein. In Part II, cortical bone was procured from a donor who died of AIDS. In both Parts I and II, the cortical bone was ground to yield particle sizes of 90 to 500 microns. Test samples were treated with a virucidal agent and demineralized in HCl. Control samples were left untreated. All samples were cocultivated with stimulated peripheral blood lymphocytes and assayed for p24 core protein, reverse transcriptase, and viral gag gene by polymerase chain reaction (PCR). In Part I, the HIV spiking experiment, untreated virus infected particulate bone was positive for HIV replication. Treated samples were negative when assayed for HIV. Bone samples in Part II, HIV infected bone, were positive by PCR. Replication of viable HIV could not be demonstrated after treatment. It was concluded that demineralization and treatment with a virucidal agent inactivates HIV in spiked and infected bone.
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PMID:HIV inactivation in a bone allograft. 128 53

An aqueous extract from the marine red alga, Schizymenia pacifica has been tested in a cell free system for its effect on reverse transcriptase from avian retrovirus (avian myeloblastosis virus), and mammalian retrovirus (Rauscher murine leukemia virus). The extract inhibited reverse transcriptase from both these retroviruses but showed almost no effect, if any, on the activity of cellular DNA polymerase alpha and RNA polymerase II in vitro. Consequently it is unlikely to have an adverse effect on the growth of cultured cell. The inhibitory activity of the extract was stable over a relatively wide pH range (pH 1-11) and was not lost after pronase digestion. Inhibitory activity of the extract was lost after boiling at 100 degrees C in 0.67 N HCl, and after treatment with 100 mM NaIO4. The active principle in the extract has an apparent molecular weight in excess of 100,000 daltons. This new reverse transcriptase inhibitor is probably a polysaccharide.
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PMID:Antiretroviral activity in a marine red alga: reverse transcriptase inhibition by an aqueous extract of Schizymenia pacifica. 244 71

Polyspermine-ribonuclease (Mr approximately 17 000) and the enzyme transcriptase from Rauscher-leukaemia virus (Mr approximately 70 000) form a complex Mr approx. 160 000) such that the molar ratio of polyspermine-ribonuclease to reverse transcriptase is 5:1. The most favourable condition for complex-formation is in a solution consisting of 0.01 M-Tris/HCl buffer, pH 7.5, 0.25 M-KCl and 1 mM-Mn2+ at 37 degrees C. The association of the two enzymes retains full RNAase activity, but reverse-transcriptase activity is completely inhibited when ribonuclease-sensitive polymers such as (dG)12 x (rC)n or viral 70S RNA are used as primer templates.
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PMID:Complexing reverse transcriptase with polyspermine-ribonuclease. 616 6

mRNA, isolated from the ligamentum nuchae of fetal sheep by guanidine HCl extraction and oligo(dT) cellulose chromatography, was used to synthesize blunt-ended cDNA molecules by the successive application of AMV reverse transcriptase, DNA polymerase and S1 nuclease. The cDNA was centrifuged on a 15-30% sucrose gradient and molecules greater than 700 bp were tailed with dCTP and cloned into the PstI site of pBR322 which had been tailed with dGTP. Ampicillin-sensitive and tetracycline-resistant colonies were screened by in situ hybridization with elastin-enriched mRNA that had been terminally labeled with 32p. Recombinant plasmids prepared from strongly hybridizing colonies were characterized by restriction mapping and the plasmid with the largest insert (1300 bp) thought to contain elastin sequences was characterized in more detail. The nick-translated cDNA hybridized to a single 3.5 kb mRNA species upon blot hybridization, a size identical to that previously identified for chick elastin mRNA (Burnett et al. (1982) J. Biol. Chem. 259, 1569-1572). Nucleotide sequencing of the 5' end of the cDNA demonstrated a sequence which was extremely GC rich and which corresponded to an amino acid sequence partially homologous to that previously identified in porcine tropoelastin (Foster et al. (1973) J. Biol. Chem. 248, 2876-2879). This is the first report of the identification of a plasmid containing sequences complementary to a translated region of elastin mRNA.
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PMID:Characterization of a sheep elastin cDNA clone containing translated sequences. 632 Aug 24

The reverse transcriptase (RT) of the human immunodeficiency virus type 1 (HIV-1) is the major target for antiretroviral therapy of the acquired immunodeficiency syndrome (AIDS). While some inhibitors exhibit activity against most retroviral RTs, others are specific for the HIV-1 enzyme. To develop an animal model for the therapy of the HIV-1 infection with RT inhibitors, the RT of the simian immunodeficiency virus (SIV) was replaced by the RT of HIV-1. Macaques infected with this SIV/HIV-1 hybrid virus developed AIDS-like symptoms and pathology. The HIV-1-specific RT inhibitor LY300046.HCl, but not zidovudine [3'-azido-3'-deoxythymidine (AZT)] delayed the appearance of plasma antigenemia in macaques infected with a high dose of the chimeric virus. Infection of macaques with the chimeric virus seems to be a valuable model to study the in vivo efficacy of new RT inhibitors, the emergence and reversal of drug resistance, the therapy of infections with drug-resistant viruses, and the efficacy of combination therapy.
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PMID:Animal model for the therapy of acquired immunodeficiency syndrome with reverse transcriptase inhibitors. 754 97

To identify the minimal structural elements necessary for biological activity, the rigid tricyclic nucleus of the known human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitor tetrahydroimidazobenzodiazepinthione was subjected to systematic bond disconnection to obtain simpler structures. A rational selection and testing of modeled analogs containing these potential pharmacophoric moieties led to the discovery of a new series of nonnucleoside inhibitors of RT. The lead compound of this new PETT series of nonnucleoside RT inhibitors, N-(2-phenylethyl)-N'-(2-thiazolyl)thiourea (LY73497), was found to inhibit HIV-1 but not HIV-2 or simian immunodeficiency virus in cell culture at micromolar concentrations. This derivative was also found to inhibit HIV-1 RT. Through an integrated effort involving synthesis and molecular modeling, compounds with nanomolar potency against HIV-1 in cell culture were developed. In these studies, LY300046-HCl was identified as a potent nonnucleoside inhibitor of HIV-1 RT possessing favorable pharmacokinetic properties.
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PMID:The PETT series, a new class of potent nonnucleoside inhibitors of human immunodeficiency virus type 1 reverse transcriptase. 757 25

In amphibians and mammals, luminal H+ secretion by the stomach requires Cl-. It is widely accepted that a basolateral Cl-/HCO3- exchanger in the acid-secreting oxyntic cell restores the Cl- deficit resulting from apical HCl secretion. In this study, we used reverse transcriptase-polymerase chain reaction (RT-PCR) to generate a 1,200-bp fragment specific to a basolateral isoform of the Na(+)-K(+)-Cl- cotransporter in the gastric fundus of Necturus maculosus. By Northern analysis, we observed that gastric mucosa expresses greater than fivefold higher levels of mRNA encoding this cotransporter than any other tissue in the gastrointestinal tract. Feeding results in > 100% increases in mRNA levels in acid-secreting fundic mucosa but does not alter mRNA levels in the neighboring and non-acid-secreting antral mucosa or duodenum. Flux measurements using in vitro fundic mucosae indicate that acid secretion requires Na+ in the nutrient (i.e., serosal side) perfusate, is modulated by changes in nutrient K+ levels, and is inhibited by nutrient solutions containing 50 microM bumetanide, a recognized blocker of Na(+)-K(+)-Cl- cotransport. These findings suggest that this basolateral transporter plays a dominant and previously unsuspected role in secretion of HCl across the apical membrane.
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PMID:Role of basolateral Na(+)-K(+)-Cl- cotransport in HCl secretion by amphibian gastric mucosa. 763 51

Plasmodium vivax-infected blood samples were collected from patients in the field during malaria transmission season. Total RNA of the parasites was extracted by guanidine HCl/cesium chloride centrifugation. mRNA was purified through oligo-dT cellulose. Double stranded cDNA were synthesized with AMV reverse transcriptase by Huynh's method. lambda gt11 phage was used as the vector. A cDNA library of the erythrocytic stage P. vivax was constructed after recombination of DNA and package in vitro.
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PMID:[Construction of a cDNA library of the erythrocytic stage of Plasmodium vivax]. 795 56


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