Protein Components of Bacteriophages Lambda and Lambda Virulent

Parallel studies have been made of the protein coats of the temperate bacteriophage lambda and of a deletion mutant, lambda virulent. A new method for preparing ghosts of both phages by the action of Cu(++) is described. Protein ghosts of both phages can be dissolved in citrate at pH values below 3, more rapidly in the presence of 8 m urea. Both phages yielded three apparently identical protein components which can be separated by thin-layer gel filtration and thin-layer gel electrophoresis. The protein of molecular weight 47,000 +/- 1,500 represents about 55% of the protein of the ghosts and is therefore likely to be the subunit of the head. The other proteins of molecular weight 30,000 +/- 1,500 and 16,000 +/- 1,500 represent approximately 25% and 20% of the protein, respectively. Amino acid analyses of the ghosts from the two phages have been carried out and show no significant differences. The buoyant density of phage lambda virulent is 0.016 g/ml less than that of lambda. Since no differences have been found in the protein components of the two phages, this indicates that the virulent mutant contains approximately 16% less deoxyribonucleic acid than the temperate phage.