The amino acid sequence of an extracellular nuclease of Staphylococcus aureus. II. The amino acid sequences of tryptic and chymotryptic peptides.

Treatment of the extracellular nuclease of Staphylococcus aureus, strain V8, with cyanogen bromide was previously shown to produce five polypeptides which could be arranged in a linear order. Trypsin digestion of these yielded sets of peptides, in each of which the carboxyl-terminal fragment could be identified by the absence of lysine or arginine, or by the presence of homoserine. The amino acid sequence of each tryptic peptide has been determined. These results, together with the isolation and characterization of peptides produced by chymotrypsin digestion of the intact nuclease, account closely for the amino acid composition of the cyanogen bromide fragments.