An RNA‐Dependent Nucleoside Triphosphate Hydrolase from Krebs‐II Ascites Tumor Cells

Abstract

A novel enzymatic activity, RNA-dependent NTPase, was isolated from [mouse] Krebs-II ascites tumor cells. This activity is associated with ribosomes and can be detached from them by washing in KCl solutions of a > 0.3 M concentration. The enzyme hydrolyzes all the 4 nucleoside triphosphates to the corresponding nucleoside diphosphates and Pi. The rate of NTP hydrolysis increases about 10-fold in the presence of natural RNA and synthetic polyribonucleotides [except poly(G)]. Natural DNA, both double- and single-stranded, are poor cofactors, although poly(dA) and poly(dT) stimulate, to a certain extent, the rate of ATP hydrolysis. Possible involvement of RNA-dependent NTPase in protein biosynthesis is discussed.