Metabolic differences in deoxyribonucleoside triphosphate hydrolysis between rat liver and Yoshida sarcoma cell...

Enzymatic activities for deoxyribonucleoside triphosphate hydrolysis associated with Yoshida sarcoma and normal rat liver chromatins were comparatively studied. Deoxyribonucleoside triphosphate-hydrolyzing activities were isolated from purified chromatins of Yoshida sarcoma cells and normal rat liver, and gel-filtered on Sephadex G-200 columns. A single peak of dUTP-hydrolyzing activity from the Yoshida sarcoma chromatin and three peaks from the normal liver chromatin were observed. The first peak from the normal chromatin hydrolyzed dATP, dCTP and TTP mainly to the corresponding deoxyribonucleoside diphosphates, and dUTP and dGTP to the corresponding di- and mononucleotide forms. The activity in the first peak from the normal liver chromatin had an apparent Km of 2.5 X 10(-4) M for dUTP, required divalent cations and was inhibited by NaF. The peak from the Yoshida sarcoma chromatin corresponding to the first peak from the normal liver chromatin hydrolyzed all five deoxyribonucleoside triphosphates to deoxyribonucleoside diphosphates with minor co-production of mononucleotides. The enzyme activity from the malignant cells had an apparent Km of 2.5 X 10(-5) M for dUTP, required Mg2+, but was not inhibited by NaF.