Gentiobiose, a constituent of deoxyribonucleic acid from coliphage T6.

The deoxyribonucleic acid of the T-even coliphages contains glucosylated and nonglucosylated 5-hydroxymethylcytosine in place of cytosine (l-6). In the case of deoxyribonucleic acid from phage T6, 72y0 of the 5-hydroxymethylcytosine residues are diglucosylated. In T2 deoxyribonucleic acid, 70% of the 5-hydroxymethylcytosine residues are monoglucosylated, but 5% bear diglucosyl units. A recent investigation of the configuration of the disaccharides bound to the 5-hydroxymethylcytosine nucleotides of deoxyribonucleic acid from T2 and T6 showed the glucose units to be p linked to each other and joined to the hydroxymethyl group of the 5-hydroxymethylcytosine by an cr linkage (6). In the present study, the disaccharide from T6 deoxyribonucleic acid was identified as gentiobiose,