Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

omicron-Phenanthroline, a zinc chelating agent, is known to inhibit the DNA polymerase activity of cellular DNA-dependent and viral RNA-dependent DNA polymerases. We find that omicron-phenanthroline does not inhibit the reverse transcriptase-associated RNase H activity of retroviruses. Kinetic studies, using DNA template-primers as an inhibitor of RNase H, suggest that zinc does not play any role in template-primer binding by reverse transcriptase. These results also indicate a distinct binding site for the template and triphosphate substrates. Cellular RNase H from calf thymus and RNase H-II from Rauscher leukemia virus are likewise resistant to omicron-phenanthroline inhibition, implying non-involvement of zinc in the nucleic acid hydrolysis by these enzymes.
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PMID:Reverse transcriptase-associated ribonuclease H does not require zinc for catalysis. 8 44

In the endogenous reverse transcriptase reaction, equine infectious anemia virus is able to synthesize complementary DNA (cDNA) of 8,000 nucleotides in high yield. After 2 h in 50 muM dNTP, about 2.8 mug of cDNA per mg of protein is produced, almost 30% of which is long cDNA. The system thus compares favorably with the other two well-characterized endogenous reaction systems, Moloney murine leukemia virus and avian sarcoma virus. Elongation rates of 100 to 150 nucleotides per min have been observed; these rates are comparable to those seen with purified avian myeloblastosis virus reverse transcriptase and significantly higher than those observed in vivo. In the absence of actinomycin D, equine infectious anemia virus does not require high dNTP levels for either optimal incorporation or long cDNA synthesis. The amount of long cDNA synthesized is maximal at 2 h in 50 muM dNTP; neither longer time nor higher dNTP levels (through 1.8 mM) increased this yield. Half-maximum yield in 2 h was achieved at about 15 muM dNTP, which is very similar to the published K(M)'s for isolated avian and murine reverse transcriptases. Total incorporation, on the other hand, continues to rise slowly through 1 mM dNTP; the half-maximum was 30 to 50 muM dNTP. In the presence of 100 mug of actinomycin D per ml, however, higher dNTP levels are required for long cDNA synthesis. We conclude that equine infectious anemia virus is exceptionally well-suited to studies of the physical organization of the retrovirus genome and to investigations of the mechanism of synthesis of the double-standard cDNA endogenous reaction product.
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PMID:Synthesis of long complementary DNA in the endogenous reaction by equine infectious anemia virus. 8 22

Detergent-disrupted virions of Moloney murine leukemia virus synthesize a 9 kbp double-stranded infectious DNA. It contains mainly full-length, single-stranded DNA, and its infectivity and size are insensitive to digestion by the single-strand-specific S1 nuclease. Analysis of fragmentation of the DNA using restriction endonucleases has shown that it is indistinguishable from the linear double-stranded DNA synthesized in infected cells. On the basis of the positions of the cleavage sites for a number of enzymes, the 9 kbp DNA has a 575 base direct terminal repetition. It is longer than the viral RNA at both ends, evidently due to repetitive copying of segments of the RNA. Virions also synthesize an 8.4 kbp double-stranded circular DNA that lacks one copy of the terminal repetition, as well as viral DNA longer than 9 kbp. The enzymatic machinery in the virions of retroviruses therefore appears to be responsible for all the steps involved in making fully double-stranded linear and one form of circular DNA.
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PMID:In vitro synthesis of a 9 kbp terminally redundant DNA carrying the infectivity of Moloney murine leukemia virus. 8 64

RNA-directed DNA polymerase was purified from spleens of Balb/c and NMRI mice infected with Rauscher murine leukemia virus. The method includes cell fractionation and lysis of microsomal fraction, chromtography on Sephadex G-200 and phosphocellulose. Estimation of molecular weight from the sedimentation rate of the purified enzyme in a glycerol gradient was consistent with a structure containing one polypeptide with a molecular weight of 70,000. Purified RLV DNA polymerase from spleen could transcribe purified DNA polymerase from purified virions. This simple preparation method offers a procedure for large scale preparation of the RNA-directed DNA polymerase which can be used for synthesis of DNA complementary to mRNA.
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PMID:Purification of RNA-directed DNA polymerase from mouse spleen infected with Rauscher leukemia virus. 8 71

We have investigated the process by which the single-stranded RNA genome of Moloney murine leukemia virus is copied into DNA in vitro. DNA synthesis if initiated near the 5' end of the genome, and the elongation of the growing chain occurs by a jumping mechanism whereby the DNA synthesized at the 5' end of the genome is elongated along the 3' end. Unique DNA fragments synthesized beyond the 5' end of the genome in vitro have, at their 5' and 3' ends, copies of unique sequences from the 5' and 3' ends of the genome. These flank a copy of the 49- to 60-nucleotide terminally redundant sequence. These results indicate that the terminal redundancy serves as a "bridge" to allow a DNA molecule synthesized at the 5' end of the genome to serve as a primer for synthesis from the 3' end.
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PMID:Structure of products of the Moloney murine leukemia virus endogenous DNA polymerase reaction. 9 Jan 61

Studies are described on the interrelationships between divalent metals, dNTP's and PPi in determining the properties of complementary DNA (cDNA) product from the in vitro reverse transcriptase reaction with detergent-treated Moloney murine leukemia virus. In spite of the several-fold greater amount of cDNA product with Mn2+ than with Mg2+, net yield of high-molecular-weight cDNA was much greater with Mg2+ thant with Mn2+. This held true, as well, for the reactions containing excess dNTP or dNTP plus PPi, both of which (as has been reported for Mg2+) promote synthesis of high-molecular-weight cDNA product. Hif total dNTP concentration remained important for maximum high-molecular-weight product with Mg2+ and was not replaced by simply providing dNTP in excess over Mg2+. Under the conditions tested here, addition of PPi did not further increase cDNA product size with Mg2+ when compared with dNTP in excess over Mg2+. Extent of degradation of the RNA template during the incubations was correlated with the size of cDNA product.
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PMID:Optimal conditions for synthesis of long complementary DNA product with Moloney murine leukemia virus. 9 Jan 69

An RNA-directed DNA polymerase was purified from a cell line derived from a radiation-induced lymphoma in NIH Swiss mice which produced non-infectious type C virus particles. The enzyme was isolated from a high speed particulate fraction which bands at a density of 1.16--1.19 g/ml in a sucrose gradient, and purified by successive chromatography on DEAE-cellulose, phosphocellulose and hydroxyapatite. The purified DNA polymerase has a molecular weight of 68 000, a pH optimum of 7.5, a KCl optimum of 50 mM, and a Mn2+ optimum of 0.25 mM. It prefers (dT)15 . (A)n to (dT)15 . (dA)n as the primer template and transcribes the poly(C) strand of (dG)15 .(C)n and (dG)15 . (OMeC)n. It transcribes heteropolymeric regions of avian myeloblastosis virus 70 S RNA, and is inhibited by antiserum to Rauscher murine leukemia virus DNA polymerase. Comparison of the properties of DNA polymerase purified from radiation-induced lymphoma cells with the DNA polymerase purified from non-defective murine type C RNA tumor viruses shows that the mouse lymphoma enzyme is both biochemically and immunologically related to murine leukemia virus DNA polymerases.
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PMID:Characterization of an RNA-directed DNA-polymerase from a cell line derived from a radiation-induced lymphoma in mice. 9 May 22

A discrete, 600-nucleotide-long plus-strand DNA has been identified among the products of reverse transcription by virions of Moloney murine leukemia virus. Its polarity was shown by hybridization to minus-strand DNA. It appears to be copied from the right end of minus-strand DNA because (i) its restriction endonuclease cleavage pattern corresponds to the redundant 600-base segment found at either end of the ultimate double-stranded reverse transcription products, (ii) its synthesis is actinomycin D sensitive, and (iii) its synthesis begins during the first hour of a reverse transcription reaction when only the right-hand end of minus-strand DNA is available as template. We therefore call this DNA plus-strong-stop DNA by analogy with the minus-strong-stop DNA copied from the left end of the viral RNA. Both strong-stop DNAs are made early during in vitro reactions and decline in concentration later, consistent with postulated roles as initiators of long minus- and plus-strand DNA. Unlike minus-strong-stop DNA, plus-strong-stop DNA remains as a double-stranded nucleic acid after its synthesis, as shown by S1 nuclease resistance. A primer to initiate plus-strong-stop DNA synthesis has not been identified; the product found thus far has no detectable RNA attached to it.
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PMID:Synthesis of a 600-nucleotide-long plus-strand DNA by virions of Moloney murine leukemia virus. 9 28

The in vitro reaction results of virus-associated DNA polymerases for the demonstration of plasma-suspended particles of avian leukemia virus (AMV) and of hepatitis type B virus (HBV) were compared. AMV particles could be identified by the transcription of the templates poly mC(dG)12-18, poly rAT10, and poly d(AT) using standardized reaction mixtures. With comparable test conditions, no DNA polymerase activity was found in human plasma containing HBV. These findings and the results of a systematic study of factors influencing the polymerization assays are discussed.
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PMID:Problems with particle-associated DNA polymerase assays in the diagnosis of plasma-suspended viruses. 9 14

A cytochemical study of a case of acute myelomonocytic leukaemia, which arose after radiation therapy and polychemotherapy for Hodgkin's disease, is presented. The distribution of the DNA content of the circulating blood cells appears to be different from the unimodal diploid distribution reported in the literature for acute myelomonocytic leukamias not associated with therapy. This finding seems to strengthen the hypothesis, already put forward by Marinone et al. (1979), that a particular pattern of DNA content distribution could be characteristic of leukaemias linked to chemotherapy and radiotherapy.
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PMID:A case of acute myelomonocytic leukaemia associated with therapy: Feulgen-DNA microdensitometric determinations. 9 10


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