Purification of B. megatherium phage G and evidence for a muralytic enzyme as an integral part of the phage

Abstract

The purification of B. megatherium G phage is described and it is shown that DEAE cellulose chromatography combined with conventional methods gave a phage preparation which was at least 95 per cent pure, and contained 2.16 #g nitrogen/10 n infective particles. The phage particle weight in molecular weight units was 91 × 106. The small amount of contaminating material appeared to represent phage "ghosts." An essentially 1 : I ratio of particles to infective units was found when data from electron microscopic counts or data from chemical analysis were related to phage infectivity. Comparison, by several methods, of the G phage and coliphage T2 shows that T2 is 2.6 times larger than G phage. The specific activity of the muralytic component obtained by disintegration of phage preparations with urea was unchanged by the purification indicating that the phage-"bound" muralytic activity is an integral part of the phage structure. © 1962, Rockefeller University Press., All rights reserved.