On the specificity of bacteriophage-induced hydroxymethylcytosine glucosyltransferases I. Specificity difference between the hydroxy-methylcytosine α-glucosyl transferases induced by bacteriophages T2, T4 and T6

T2 DNA has been further glucosylated in vitro by the hydroxymethylcytosine α-glucosyltransferase (UDPglucose: hydroxymethylcytosine α-glucosyltransferase) specific for T4 and T6 bacteriophage in the presence of uridine disphosphate [¹⁴C] glucose. Analysis of formic acid-diphenylamine digests prepared from [¹³⁴C]DNA preparations thus synthesized has shown that it is possible to formulate differences in enzymic specificity between the various HMC α-glucosyltransferases in terms of the primary structrue of the substrat DNA. The α-transferases specific for T4 and T6 bacteriophage glucosylate HMC residues present in 5-hydroxymethyldeoxycytidine-purine doexyriboside sequences rapidly, while T2 HMC α-glucosyltransferase reacts with HMC residues at those sites at about one-twelfth of the rate.

It is also shown that the further glucosylation in excess of 28% of the free HMC residues¹ is mainly the result of an exchange reaction.