The Amino Acid Sequence of T4 Phage Lysozyme

T4 phage lysozyme was partially hydrolyzed in dilute acid (pH 2) at 105°. By this treatment, hydrolysis occured mainly at the peptide bonds involving the NH2 and COOH groups of aspartic acid and asparagine residues in the protein. The peptide fragments thus obtained were purified by means of column chromatography, gel filtration, paper chromatography, and paper electrophoresis. In addition to free aspartic acid, leucine, valine, and glutamic acid, nine peptides were isolated and their complete or partial structures were determined. These peptides confirmed the linkages of tryptic peptides proposed on the basis of earlier studies with chymotryptic and peptic peptides. The primary structure of T4 phage lysozyme was thus established.