Endogenous polymerases

Likewise, endogenous polymerase activity of isolated nuclei from these strains is significantly less sensitive to phenylamides than that of nuclei from sensitive strains (Table IV). This indicates that in both species a change in the target site of metalaxyl is responsible for resistance. Apparently both mutagen induced... 

Studies have demonstrated that one such method is to examine the effects of disinfectants on endogenous RNA-dependent DNA polymerase (i.e. reverse transcriptase) activity. In essence, HIV is an RNA virus after it enters a cell the RNA is converted to DNA under the influence of reverse transcriptase. The virus induces a cytopathic effect on T lymphocytes, and in the assay reverse transcriptase activity is determined after exposure to different concentrations of various disinfectants. However, it has been suggested that monitoring residual viral reverse transcriptase activity is not a satisfactory alternative to tests whereby infectious HIV can be detected in systems employing fresh human peripheral blood mononuclear cells. 

Burlde A (2005) Poly(ADP-ribose). The most elaborate metabolite of NAD. Febs J 272 4576-4589 Burlde A, Brabeck C, Diefenbach J, Beneke S (2005) The emerging role of poly(ADP-ribose) polymerase-1 in longevity. Int J Biochem Cell Biol 37 1043—1053 Cardenas-Corona M, Jacobson E, Jacobson M (1987) Endogenous polymers of ADP-ribose are associated with the nuclear matrix. J Biol Chem 262 14863—14866 Chang P, Jacobson MK, Mitchison TJ (2004) Poly(ADP-ribose) is required for spindle assembly and structure. Nature 432 645-649... 

Relationships between histone methylation and DNA methylation and histone acetyation and DNA methylation have been reported [191,314,315], A similar relationship may exist between poly(ADP ribosylated) HI and DNA methylation. Inhibition of poly(ADP-ribose) polymerase with 3-aminobenzamide increases the susceptibility of L929 mouse fibroblast nuclei to be methylated by endogenous DNA methyltransferases [316,317], Further, there is evidence that poly(ADP ribosylation) protects CpG islands located at the 5 end of housekeeping genes from methylation [318], Future studies will likely reveal an interesting dynamic relationship between histone methylation, histone acetylation, and histone poly(ADP-ribosylation). 

Vidarabine inhibits vitally induced DNA polymerase more strongly than it does the endogenous enzyme. Its use is now limited to topical treatment of severe herpes simplex infection. Before the introduction of the better tolerated acyclovir, vidarabine played a major part in the treatment of herpes simplex encephalitis. 

Davidse, L.C., Hofman, A.E., Velthuis, G.C.M. 1983. Specific interference of metalaxyl with endogenous RNA polymerase activity in isolated nuclei of Phytophthora megasperma f.sp.medicaginis. Exp. Mycol. 344-361. 

Fig. 9. Inhibition of endogenous RNase-sensitive FLV-DNA-polymerase activity by tilorone and congeners...

The inhibition of the endogenous activity of FLV-DNA polymerase by tilorone and congeners is shown in Fig. 9. A maximum inhibition was obtained with DEAP-fluoranthene. The inhibitory responses of tilorone (DEAE-fluorenone), DMAA-dibenzothiophene and DEAA-fluorene were of the same magnitude whereas, DMAA-dibenzofuran showed a weak response. It is interesting to note that the mono-substituted congener MEAA-fluorene did not inhibit the endogenous reaction at any concentration. 

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