Deoxycytidine Di- and Triphosphate Cleavage by an Enzyme Formed in Bacteriophage-infected Escherichia coli

The deoxyribonucleic acid of bacteriophages T2, T4, and T6, in contrast to the deoxyribonucleic acid of their host, has hydroxymethylcytosine in place of cytosine ( 1)) with a fixed fraction of these bases linked to one or more glucose residues (2).Infection of Escherichia coli by these bacteriophages leads to the development of new enzymes which are responsible for the synthesis of the deoxyribonucleic acid peculiar to these viruses.Among these enzymes are one which converts deoxycytidine 5'-monophosphate to 5-hydroxymethyl deoxycytidine 5'-monophosphate (3), another which phosphorylates this monophosphate (4, 5), a group of enzymes which add glucose to the hydroxymethylcytosine residues after their incorporation into a deoxyribonucleic acid polymer (4, 6), and further, an enzyme which degrades deoxycytidine triphosphate, making it unavailable for deoxyribonucleic acid synthesis (4, 7, 8).A detailed study of the latter enzyme was the purpose of the present work.Reports of the preliminary investigations (4,8) did not provide adequate descriptions of the purification and properties of the deoxycytidine triphosphate-splitting activity.A recent study by Koerner et al. ( 7) supplies some of these data.The present