Polymerase activity

Manganese ions enzyme activators, 6,578 probes, 6,563 RNA polymerases activation, 6, 585 transport microbes, 6, 569 plants, 6, 572 Manganese oxide colloidal... 

DNA polymerase I has been purified to homogeneity. When the pure enzyme is treated with subtilisin, a proteolytic enzyme from Bacillus subtilis, the polymerase is cleaved into two pieces. The small fragment retains the 5 to 3 nuclease activity, whereas the larger piece, called a Klenow fragment, has both polymerase activity and the 3 to 5 exonuclease activity. The Klenow fragment is sold commercially for use in labeling DNA for use in detecting recombinant DNA. 

This enzyme is associated with the virions of RNA tumor viruses such as the Rous sarcoma virus (RSV). The enzyme has remarkable enzymatic activity in that it can catalyze several seemingly diverse steps in the synthesis of double-stranded DNA from the single-stranded RNA viral genome. The enzyme uses a tRNA for tryp-tophan as a primer to make a copy of DNA that is complementary to the viral RNA. The resulting RNA-DNA hybrid is converted to a double-stranded DNA molecule by ribon-uclease (RNase)H and DNA-dependent DNA polymerase activities that are intrinsic to reverse transcriptase. 

Zhuang, Z. X., Shen, Y., Shen, H. M., Ng, V. andOng, C. N. (1996). DNA strand breaks and poly(ADP-ribose) polymerase activation induced by crystalline nickel subsulfide in MRC-5 lung fibroblast cells, Human Exper. Toxicol., 15, 891-897. 

Decker P, Muller S (2002) Modulating poly (ADP-ribose) polymerase activity potential for the prevention and therapy of pathogenic situations involving DNA damage and oxidative stress. Curr Pharm Biotechnol 3 275-283... 

Escargueil AE, Poindessous V, Soares DG Sarasin A, Cook PR, Larsen AK. (2008) Influence of irofulven, a transcription-coupled repair-specific antitumor agent, on RNA polymerase activity, stability and dynamics in living mammalian cells. J Cell Sci 121 1275-1283. 

Linn, S Kairis, M. and Holliday, R. Decreased Fidelity of DNA Polymerase Activity Isolated from Aging Human Fibroblasts , Proc. Natl, Acad. Sci. (1976) 73, 2818. 

Pharmacology Rifampin inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase, but does not inhibit the mammalian enzyme. Cross-resistance has only been shown with other rifamycins. Rifampin at therapeutic levels has demonstrated bactericidal activity against intracellular and extracellular Mycobacterium tuberculosis organisms. Pharmacokinetics ... 

Pharmacology Lamivudine is a synthetic nucleoside analog with activity against HIV and hepatitis B virus (HBV). Lamivudine is phosphorylated intracellularly to lamivudine 5 -triphosphate (L-TP). Incorporation of the monophosphate form into viral DMA by HBV polymerase results in DMA chain termination. L-TP also inhibits the RNA- and DNA-dependent DMA polymerase activities of HIV-1 reverse transcriptase. 

Nevirapine binds directly to reverse transcriptase (RT) and blocks the RNA-dependent and DNA-dependent DNA polymerase activities by causing a disruption of the enzyme s catalytic site. The activity of nevirapine does not compete with P.1118... 

LysS/LysE an additional chloramphenicol resistant plasmid carries the gene forT7 lysozyme under constitutively active promoters. T7 lysozyme inhibits the activity of T7 polymerase thereby reducing basal (uninduced) polymerase activity/ protein expression. LysE express higher levels of T7 lysozyme for tighter control. pLacI an additional chloramphenicol resistant plasmid carries the gene for high level production of the lac repressor to reduce basal expression. 

So far this class of carbazole alkaloids contains only two natural products, calothrixin A and its N-deoxy-derivative calothrixin B. These two pentacyclic metabolites with a quinolino[4,3- 7]carbazole-l,4-quinone framework displayed potent inhibitory effects on the in vitro growth of both human malarial parasites and human cancer cells and inhibition of RNA polymerase activity. Owing to this pharmaceutical potential, these natural products have attracted the synthetic interest of various research groups (8). 

Sethi, V. S. 1976. Inhibition of mammalian and oncornavirus nucleic acid polymerase activities by alkoxybenzophenantridine alkaloids. Cancer Research, 36 2390-2395. 

DNA polymerase and also acts as an alternative substrate. The incorporation of one cidofovir molecule into the growing DNA chain slows replication sequential incorporation of two molecules halts DNA polymerase activity. 

Vidarabine s specific mechanism of action is not fully understood. Cellular enzymes convert this drug to a triphosphate that inhibits DNA polymerase activity. Vidarabine triphosphate competes with deoxyadeno-sine triphosphate (dATP) for access to DNA polymerase and also acts as a chain terminator. Although vidarabine is incorporated into host DNA to some extent, viral DNA polymerase is much more susceptible to inhibition by vidarabine. Vidarabine also inhibits ri-bonucleoside reductase and other enzymes. Resistance occurs as a result of DNA polymerase mutation. 

Anabolic activities of testosterone, such as increases in amino acid incorporation into protein and in RNA polymerase activity, have been demonstrated in skeletal muscle. Apart from the direct anabolic effects in specific tissue, androgens antagonize the protein catabolic action of glucocorticoids. The androgen compounds with the greatest ratio of protein anabolic effects to virilizing effects are the 19-nortestosterone derivatives. Compounds that are used clinically (Table 63.3) include nandrolone phenpropionate (Durabolin), nandrolone decanoate... 

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