Abstract
In order to determine the composition of the PhiX174 coat, PhiX particles labeled in most of the amino acids have been dissociated, and the proteins separated by electrophoresis on polyacrylamide gels. The molar ratios of the four proteins calculated from the fraction of radioactivity in each peak and the molecular weights of the individual proteins suggest that the capsid is composed of 60 molecules of the 48,000 daltons protein and that each of the 12 spikes is composed of one molecule of the 36,000 daltons protein and five each of the 19,000 and 5,000 daltons proteins.