Amino acid sequence of beta-galactosidase. V. Isolation and sequences of chymotryptic peptides.

The amino acid sequence of 72 chymotryptic peptides isolated from 14C-, 3H-labeled carboxymethyl-beta-galactosidase has been determined. A variety of techniques were used in the isolation procedures including separation by solubility, size, and ion exchange and paper chromatography. These peptides contain approximatley 500 amino acids, range in size from 2 to 26 residues, and give overlaps with tryptic peptides of 16 to 55 residues. Peptides from this digest and those reported earlier from tryptic digests account together for the sequence of about 600 of the 1021 residues in the subunit.