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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study describes the separation and purification of a reverse transcriptase and cellular DNA polymerases from the human spleen of a patient with myelofibrotic syndrome. The specific requirements with respect to bivalent cations and template-primers for DNA polymerase-alpha, DNA polymerase-beta and DNA polymerase-gamma, as well as for the reverse transcriptase, are reported. Sedimentation-velocity measurements of the purified enzymes gave values of 150000, 40000, 100000 and 70000 daltons for DNA polymerase-alpha DNA polymerase-beta, DNA polymerase-gamma and the reverse transcriptase respectively. Serological studies have shown that the reverse transcriptase from human spleen is not antigenically related to cellular DNA polymerase-alpha, -beta or -gamma, but is antigenically related to reverse transcriptase from simian sarcoma virus and gibbon-ape leukaemia virus.
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PMID:Purification, biochemical characterization and serological analysis of cellular deoxyribonucleic acid polymerases and a reverse transcriptase from spleen of a patient with myelofibrotic syndrome. 7 8

Sequential reverse transcriptase, DNA polymerase, and S1 nuclease reactions can be employed to synthesize double-stranded DNA representing messenger RNA. Using reverse transcriptase products made from partially purified lysozyme, ovomucoid, and ovalbumin messengers from hen oviduct, we have characterized the Escherichia coli DNA polymerase I reaction. We have optimized for a high yield of full length second strands under conditions which require only a small amount of mRNA. The effects of several parameters (time, enzyme levels, salt concentration, monovalent cation, and temperature) on the length of products synthesized by DNA polymerase I have been investigated. Each has a significant influence on the proportion of products which are full length. Under our conditions the three reactions are efficient in synthesizing full length duplex DNA from partially purified mRNA fractions or from total poly(A)-containing RNA.
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PMID:Synthesis of double-stranded DNA complementary to lysozyme, ovomucoid, and ovalbumin mRNAs. Optimization for full length second strand synthesis by Escherichia coli DNA polymerase I. 7 87

Particulate DNA polymerase activity that copied poly(2'-O-methylcytidylate) . oligodeoxyguanylate and banded at a density of 1.15 to 1.20 g/ml in sucrose gradients was detected in 8 of 16 human ovary tumors and in 11 of 16 malignant prostate tissues. None of the 10 nonmalignant ovary and prostate tissues examined contained detectable particulate DNA polymerase activity that copied poly(2'-O-methylcytidylate) . oligodeoxyguanylate. Since poly(2'-O-methylcytidylate) . oligodeoxyguanylate is effectively copied by oncornavirus RNA-directed DNA polymerase (reverse transcriptase) although not by the known species of human cell DNA polymerase, these results are interpreted as supporting the concept that some malignant human tissues contain particle-associated reverse transcriptase activity.
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PMID:Detection in human ovary and prostate tumors of DNA polymerase activity that copies poly(2'-O-methylcytidylate) . oligodeoxyguanylate. 7 7

4'-(9-Acridinylamino)methanesulphon-m-anisidide (AMSA) (NSC 141549), an acridine derivative with activity against a variety of laboratory tumors in vivo, is presently undergoing Phase 1 clinical evaluation. The interaction of AMSA with DNA and its effects on nucleic acid-polymerizing enzymes were examined in an attempt to define the site of cytotoxicity of AMSA. Binding of AMSA to DNA, as demonstrated by equilibrium dialysis and spectrophotometric methods, appears to be similar to other aminoacridines, in that two types of binding sites (type 1 and type 2) were observed. Fluorescence studies and thermal denaturation studies gave strong evidence that AMSA type 1 binding was by intercalation into DNA. The binding of AMSA to DNA was without marked base-pair specificity. Furthermore, the effect of AMSA on nucleic acid-polymerizing enzyme activities (mouse embryo DNA polymerase alpha, avian myeloblastosis virus reverse transcriptase, and Escherichia coli RNA polymerase) was studied. Inhibition of enzyme activity by AMSA appeared to be independent of DNA base sequence. The relatively high concentrations of AMSA required for inhibition of these enzymes as compared to the concentrations of AMSA necessary for cytotoxicity in vitro suggest that the interaction with DNA alone might not fully explain its antitumor activity.
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PMID:Interaction of 4'-(9-acridinylamino)methanesulfon-m-anisidide with DNA and inhibition of oncornavirus reverse transcriptase and cellular nucleic acid polymerases. 7 12

Endogenous cellular genetic information related to the avian leukosis virus gene encoding RNA-directed DNA polymerase was studied, using a marker rescue assay to detect biological activity of subgenomic fragments of virus-related DNAs of uninfected avian cells. Recipient cultures of chicken embryo fibroblasts were treated with sonicated DNA fragments and were infected with a temperature-sensitive mutant of Rous sarcoma virus that encoded a thermolabile DNA polymerase. Wild-type progeny viruses were isolated by marker rescue with fragments of DNA of uninfected chicken, pheasant, quail, and turkey cells. The DNAs of these uninfected avian cells, therefore, appeared to contain endogenous genetic information related to the avian leukosis virus DNA polymerase gene.
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PMID:Marker rescue of endogenous cellular genetic information related to the avian leukosis virus gene encoding RNA-directed DNA polymerase. 7 85

beta-Lapachone is a naturally occuring compound that can be isolated from a number of tropical trees. It is shown to be a potent inhibitor of reverse transcriptase activity from both avian myeloblastosis virus and Rauscher murine leukaemia virus. In addition, it affects eukaryotic DNA-dependent DNA polymerase-alpha activity: 50% inhibition is reached in 60-min incubation time by about 8 micron beta-lapachone. Enzyme activity is inhibited irrespective of the purity of the enzyme used or of the amount or type of template/primer or substrate present. The inhibitory effect of the drug is only observed in the presence of dithiothreitol. The primary site of action of beta-lapachone appears to be the enzyme protein, as is also borne out by the specificity of its action. Eukaryotic DNA-dependent DNA polymerase-beta, prokaryotic DNA-dependent DNA polymerase I, several other nucleic acid polymerases and some completely unrelated enzymes are not affected. Reverse transcriptase and DNA-dependent DNA polymerase-alpha may be in someway related in possessing similarly exposed '--SH structures' in their active sites. beta-lapachone thus affords a novel means of studying such interrelationships and of further characterizing enzymes.
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PMID:beta-Lapachone, an inhibitor of oncornavirus reverse transcriptase and eukaryotic DNA polymerase-alpha. Inhibitory effect, thiol dependence and specificity. 7 23

The microsomal supernatant fraction obtained from a murine cell line chronically infected with and producing Rauscher leukemia virus (JLSV-10) was found to contain two forms of RNA-directed DNA polymerase (reverse transcriptase). The two enzyme forms, neither of which is detectable in uninfected cells (JLSV-9), were initially partially purified by poly(C)-agarose chromatography, and their separation was achieved by phosphocellulose chromatography. The enzyme form eluting first from phosphocellulose (0.3 M KCl), designated PC I, was found to be identical in all parameters tested to that form isolated directly from purified virions. The second enzyme peak, designated PC II, eluted from phosphocellulose at 0.5 M KCl and was not detectable in purified virions. The PC II enzyme has a molecular weight, determined by velocity sedimentation, of approximately 109,000, as compared with 70,000 for the PC I enzyme, and could not be further dissociated by exposure to high salt or nonionic detergent. Mixing purified virion or PC I DNA polymerase with uninfected cells followed by fractionation did not produce the PC II form, suggesting that it is neither an artifact of purification nor the result of fortuitous complexing of reverse transcriptase with normal cellular component(s). Both PC I and PC II enzyme forms appeared antigenically similar to virion DNA polymerase, demonstrated identical divalent cation requirements for various template-primers, and were capable of copying heteropolymeric regions of rabbit globin mRNA. However, kinetic studies of heat inactivation revealed that the PC II enzyme was far more heat labile than the PC I form, which appeared identical to the virion enzyme in this respect. Furthermore, whereas the PC I and virion-derived reverse transcriptase copied poly(C).(dG)12-18 most efficiently at a template-to-primer molar nucleotide ratio of 25:1, the PC II enzyme preferred a ratio of 5:1 for optimal rates of poly(dG) synthesis. Therefore, by these criteria, there appear to exist two intracellular forms of reverse transcriptase in the JLSV-10 Rauscher leukemia virus-producing murine cell line.
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PMID:Resolution and characterization of intracytoplasmic forms of reverse transcriptase from Rauscher leukemia virus-producing cells. 7 32

Lysates of Moloney murine sarcoma-leukemia virus [M-MSV(MLV)], a virus complex grown in the rat cell line 78A-1, were found to contain three RNase H species separable by polycytidylic acid[poly(C)]-agarose chromatography. RNase H activity (RNase H I) associated with RNA-directed DNA polymerase eluted at 0.23 M KCI from poly(C)-agarose. RNase H II, which eluted from poly(C)-agarose at 0.12 M KCI and was not associated with DNA polymerase activity, was shown to be identical to an RNase H species (designated RNase H II) previously isolated from M-MSV(MLV) by a different procedure (G. F. Gerard and D. P. Grandgenett, J. Virol. 15:785-797, 1975). M-MSV(MLV) RNase H II was established to be a random exohybridase that requires free-chain termini in its hybrid substrate for activity. Lysates of Rickard feline leukemia virus also contained RNase H activity not associated with DNA polymerase activity that eluted from poly(C)-agarose at 0.12 M KCl. A third species of enzyme from M-MSV(MLV) lysates, called RNase H III, did not bind to poly(C)-agarose in 0.06 M KCl. RNase H III was purified from lysates of M-MSV(MLV) and M-MLV (grown in mouse cells) by sequential chromatography on poly(C)-agarose, DEAE-cellulose, phosphocellulose, and polyuridylic acid-Sepharose. Purified RNase H III (i) was free of any associated DNA polymerase activity, (ii) had an apparent molecular weight of 30,000 determined by Sephadex G-100 gel filtration, (iii) had an absolute requirement for Mn2+ (1 mM optimum) for the degradation of [3H](A)n.(dT)n, (iv) was inhibited by the presence of any salt in reaction mixtures, and (v) was endoribonucleolytic in its mode of action as indicated by the size distribution of limited degradation products of [3H](A)n.(dT)n. RNase H III was inhibited by antisera prepared against Rauscher MLV and simian sarcoma virus reverse transcriptase, and the quantity of RNase H III and RNase H I present in lysates of M-MLV were reduced and increased proportionately if virus was lysed in the presence of the protease inhibitor phenylmethylsulfonyl fluoride. These results indicate that RNase H III is a proteolytic cleavage product of DNA polymerase-RNase H. Substantial RNase H activity that did not bind to poly(C)-agarose in 0.06 M KCl was also found in lysates of Harvey MSV(MLV), Rauscher MLV, and Rickard feline leukemia virus, but not in lysates of avian myeloblastosis virus.
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PMID:Multiple RNase H activities in mammalian type C retravirus lysates. 7 33

The active sites in reverse transcriptase of avian myeloblastosis virus have been selectively modified by various chemical reagents. The DNA polymerase activity is very sensitive to hydrophobic sulfhydryl reagents such as 5,5'-dithiobis(2-nitrobenzoic acid) and p-hydroxymercuribenzoate but resistant to sulfhydryl reagents with hydrophilic properties. The RNase H activity, on the other hand, is resistant to both hydrophobic and hydrophilic sulfhydryl reagents, indicating the absence of cysteinyl residues essential for RNase H activity. N-Ethylmaleimide (NEM), an amino and sulfhydryl group specific reagent, inactivates both DNA polymerase and RNase H, the later activity being fourfold more stable. Polynucleotides, but not nucleotide triphosphates, protect the two enzymatic activites of reverse transcriptase against NEM. Since pretreatment of the enzyme with 5,5' -dithiobis(2-nitrobenzoic acid) does not prevent N-ethylmaleimide from reacting with a residue necessary for DNA polymerase activity, two different reactive groups are probably involved with this enzymatic activity. The pH profile of reverse transcriptase inhibition by N-ethylmaleimide also suggests the involvement of two reactive groups essential for the DNA polymerase activity with apparent pKas of 5.5 and 6.5. Only one reactive group with a pKa of 7.5 is found associated with the RNase H activity.
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PMID:Discrimination of DNA polymerase and RNase H activities in reverse transcriptase of avian myeloblastosis virus. 7 19

The sequence of 129 nucleotides next to the poly(A) tail of encephalomyocarditis virus RNA has been determined by rapid gel sequencing of cDNA synthesized with DNA polymerase I or reverse transcriptase and a phasing primer, [5'-32P]p(dT)8dC. The sequence is in accord with (a) the pyrimidine tracts which were mapped in blocks along the cDNA, (B) the sequences of seven characteristic T1 RNase oligonucleotides in the RNA transcribed from the cDNA with RNA polymerase, and (c) a limited amount of sequence deduced by partial spleen phosphodiesterase digestion and depurination of endonuclease IV oligonucleotides. The 3' end shows little secondary structure on its own. Ten nonsense codons block all three reading frames such that at least 26 nucleotides do not code for protein. The possible function of a homology A-A-U-A-A-A with other polyadenylated RNAs is discussed.
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PMID:Sequence of 129 nucleotides at the 3'-terminus of encephalomyocarditis virus RNA. 7 85


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