Subtilisin Amylosacchariticus. II. Isolation and sequence of the tryptic and cyanogen bromide peptides.

Previous work on the primary structures of subtilisins BPN’ (1, 2), Novo (3), and Carlsberg (4) had shown that tryptic digestion and resolution of the resulting peptides by either ion exchange chromatography or gel filtration served as a useful first step in determining the amino acid sequences of these proteins. Accordingly, the diisopropylphosphoryl derivative of subtilisin Amylosacchariticus was digested with L-l-tosylamido2-phenylethyl chloromethyl ketone-trypsin as the initial step in the determination of its primary structure. To provide overlaps for the tryptic peptides as well as to obtain additional sequence information, cyanogen bromide cleavage was also performed on this protein. This paper reports the results of these studies. In the following paper (5) the results of chymotryptic hydrolysis are presented, as well as the complete sequence of the protein.