STRUCTURE AND SYNTHESIS OF A LIPID-CONTAINING BACTERIOPHAGE .3. PURIFICATION OF BACTERIOPHAGE-PM2 AND SOME STRUCTURAL STUDIES ON VIRION

Detailed procedures are given for the purification of bacteriophage PM2, and some of the difficulties met in purifying this virus are discussed. The structure of the purified virus was examined by electron microscopy of intact virus and of virus dissociated under acid or alkaline conditions or by nonionic detergents. The virus is icosahedral in shape with spikes or fibers radiating from the vertices. The diameter of negatively stained particles was 61.4 mμ. In thin sections a bilayer could be seen. This may be either a membrane or two lipoprotein shells. This bilayer was 73 Å thick but the diameter of the particle was now 56.1mμ, indicating some shrinkage during embedding. A number of stages in dissociation of the virion were observed under the conditions mentioned above. Structures which may be interpreted as cores were seen, and these were very labile once the outer envelope was removed. © 1969.