t2 and other bacterial viruses 469 



comparison with the synthetically prepared compound (Wyatt and Cohen, 

 1953; Miller, 1955).i 



The presence of glucose was first reported by Jesaitis in T4 (1954), and 

 was discovered independently in T2 by Sinsheimer (1954), and in T6 by 

 Volkin (1954). The identity of the compound was estabhshed by its behavior 

 on cliromatographic analysis. As indicated in Table II the amount of glucose 

 present varies with the coliphage strain. Cohen (1956) has reported data for 

 the glucose content of mutant strains of the coliphages and has suggested 

 on the basis of his figures that the difference between T2r+ and T2r, for 

 example, can be associated with the presence of an increased amount of 

 glucose in the DNA of the latter. Sinsheimer (1956), on the basis of analytical 

 figures for other strains, does not concur. 



While enzymatic degradation with DNAase and diesterase from snake 

 venom causes a practically quantitative breakdown of DNA to the mono- 

 nucleotide stage with T7 (Lmian and Sinsheimer, 1956), and presumably with 

 T3 and other odd-numbered phages, this is not the case with those coliphages 

 containing 5-HMC and glucose. With these, enzymatic degradation yields only 

 about 60-70 % of the total phosphorus in the form of the mononucleotide. In 

 T6, for example, while 60 % of the total thymydylic, deoxyadenylic, and de- 

 oxyguanyhc acids is found as mononucleotide, only 23 % of the hydroxy- 

 methylcytidylic acid is liberated as mononucleotide (Jesaitis, 1957). In T2 

 (Sinsheimer, 1954) and T4 (Volkin, 1954) the quantity of 5-HMC nucleotide 

 is somewhat higher (about 17 %), the percentage of the other mononucleo- 

 tides remaining the same. It will be noted that the molar proportion of glu- 

 cose to 5-HMC is below 1 in the case of T2, about 1 in T4, and is almost 2 in 

 the case of T6. These facts are of interest in connection with the conclusion 

 that the point of attachment of glucose is via the hydroxyl group of 5-HMC. 

 In the case of the hydroxymethyl cytidylic acid from T2 (Sinsheimer, 1954), 

 somewhat less than half was present as the free mononucleotide, with the 

 rest present as the monoglucose derivative. With T4 (Volkin, 1954), all of 

 the hydroxymethyl cytidylic acid liberated was in the form of the mono- 

 glucoside. With T6 (Jesaitis, 1957), on the other hand, somewhat more than 

 20 % of the liberated hydroxymethyl cytidyhc acid is present in the unsub- 

 stituted form, the remainder being found as a diglucoside. While the exact 

 structure of the latter is not known, it seems very probable that the two mole- 

 cules of the hexose are linked as a disaccharide to the 5-hydroxymethyl group 

 of the pyrimidine. Whether the major portion of the glucose present in the 

 enzyme-resistant polynucleotide residue is attached in the same fashion or 

 not is imcertain. The observation that the monoglucoside of hydroxymethyl 



^ A synthesis permitting the incorporation of C^^ into the 2 position has been recently 

 described (Weygand and Swoboda, 195G). 



