Purification And Characterization Of Ribouridylyl Terminal Transferase And Ribocytidylyl Terminal Transferase Activities From RNA Tumor Virus-Infected Avian Myeloblasts

Abstract

Two enzymes, one which catalyzes the addition of one or more cytidine 5'-monophosphate residue from cytidine 5’-triphosphate to the 3'-terminus of a ribonucleic acid primer, referred to as ribocytidylyl terminal transferase, and one which catalyzes the addition of one or more uridine 5’-monophosphate residue from uridine 5'-triphosphate to the 3'-terminus of a ribonucleic acid primer, referred to as ribouridylyl terminal transferase, have been purified from RNA tumor virus-infected avian myeloblasts. The purification procedure involved cation and anion exchange chromatography. Both enzymes were stimulated by the divalent cations Mg++ and Mn++ with optimal concentrations of 0.0001 M Mn++ and between 0.001 M and 0.004 M Mg++. The molecular weight of ribocytidylyl terminal transferase was approximately 60,000 and the molecular weight of ribouridylyl terminal transferase was approximately 56,000.