The Enzymatic Phosphorylation of Ribonucleic Acid and Deoxyribonucleic Acid

Abstract

The specificity of the enzyme purified from T2-infected Escherichia coli which catalyzes the phosphorylation of 5'-hydroxyl ends of ribonucleic acid and deoxyribonucleic acid has been examined. The enzyme also catalyzes the phosphorylation of 5'-hydroxyl groups of polynucleotides as well as 3'-mononucleotides. There is no detectable phosphorylation of nucleosides and adenosine 2'-phosphate is virtually inactive as a phosphate acceptor. The enzyme is also capable of using guanosine, cytidine, and uridine triphosphates as well as adenosine triphosphate as the phosphorylating agent. The enzyme catalyzes the quantitative phosphorylation of available 5'-hydroxyl groups occurring in a variety of different DNA preparations. When used in conjunction with alkaline phosphatase, the enzymatic phosphorylation of DNA measures the total amount of 5'-hydroxyl and 5'-phosphate ends present in DNA. The 5'-hydroxyl polynucleotide kinase was used to measure the amount of 5'-hydroxyl ends formed in DNA degraded by sonic oscillation and alkali and heat denaturation. In all of the cases, virtually no additional 5'-hydroxyl groups were formed. The 5'-hydroxyl kinase has also been detected in nuclei of rat liver and the activity partially characterized.