COMPARISON OF THE AMINO ACID COMPOSITION OF T2 AND T3 BACTERIOPHAGES* BY DEAN FRASERt

By using the apparatus (2) and medium (3) previously described, we have prepared two 4 to 5 liter batches of T2 bacteriophage by infection of the usual host, Escherichia coli, strain B. The raw titers were 1 and 3 X 1Ol2 infectious T2 particles per ml. Purification of these lysates by three or four cycles of deliberately wasteful differential centrifugation yielded some 1.5 to 2 gm. each of lyophilized T2 bacteriophage which was dried in an Abderhalden drier at 56” (boiling acetone). All batches were prepared from a master stock of T2 derived from a starting stock provided originally by Dr. Max Delbriick. The master stock and the purified T2 were typical in their behavior toward anti-T2 rabbit serum (1). As evidence of its biological homogeneity, the purified T2 was shown to give no extraneous plaque types and no more than the expected slight titer against E. coli, strain B/2, a host cell specifically resistant to T2. The purified T2 was also examined in the analytical ultracentrifuge and the electron microscope (4). Both tests indicated no discernible contaminants. In the electron microscope the phage appeared uniform and essentially free from empty membranes. The T3 preparation has been described previously (3). The amino acid analyses were made chromatographically by the Moore and Stein technique (5, 6), with use of columns of Dowex 50, with slight modifications (3, 7). For each determination a 2 to 3 mg. sample of dried virus was accurately weighed into a 13 X 100 mm. acid-cleaned test tube and mixed with 0.5 ml. of glass-distilled, constant boiling hydrochloric