title: Characterization of an RNA-directed DNA polymerase from mouse spleen infected with leukaemia virus activated during N-methyl-N-nitroso urea-induced leukaemogenesis.
abstract: An RNA-directed DNA polymerase was purified from mouse spleen infected with leukaemia virus activated during N-methyl-N-nitroso urea- (MNU-) induced leukaemogenesis. The enzyme was isolated from the microsomal fraction and purified by successive chromatography of Sephadex G-200 and phosphocellulose. Estimation of molecular weight from the sedimentation rate of the purified enzyme in a sucrose gradient gave a value of 70,000. The enzyme had a pH optimum of 7.4, a KC1 optimum of 50 mmol/l, an Mn2+ optimum of 0.2 mmol/l, and a temperature optimum of 25 degrees C, when (rA)n . (dT) 10 was used as the template-primer. It preferred (rA)n . (dT)10 as the template-primer and transcribed (rC)n . (dG) 12 and (OMeC)n . (dG)12. A comparison of the properties of this DNA polymerase with the enzyme purified from murine type C retroviruses showed that the MNU-activated virus enzyme was both biochemically and biophysically indistinguishable from murine leukaemia virus DNA polymerases.
mesh_terms: D000818:Animals; D002501:Centrifugation, Zonal; D002850:Chromatography, Gel; D007700:Kinetics; D009052:Leukemia Virus, Murine / Q000201:enzymology*; D007942:Leukemia, Experimental / Q000201:enzymology*; D008770:Methylnitrosourea / Q000494:pharmacology; D051379:Mice; D008970:Molecular Weight; D012194:RNA-Directed DNA Polymerase / Q000302:isolation & purification* / Q000378:metabolism; D013154:Spleen / Q000201:enzymology*
chemical_list: D008770:Methylnitrosourea; D012194:RNA-Directed DNA Polymerase