The Isolation and Characterization of the Tryptic, Chymotryptic, Peptic, and Cyanogen Bromide Peptides from Bovine α-Lactalbumin

Abstract

Abstract Reaction of S-aminoethyl-α-lactalbumin with cyanogen bromide results in the cleavage of the one methionyl peptide bond in the molecule to give two unique polypeptide fragments. One fragment contains the first 90 residues from the NH2-terminus of α-lactalbumin and the other contains the remaining 33 residues in the molecule including the COOH-terminus. The tryptic, chymotryptic, and peptic peptides from these fragments, or from S-carboxymethyl-α-lactalbumin, have been purified by ion exchange chromatography and gel filtration. These peptides represent the necessary overlaps in sequence that are required to deduce the complete amino acid sequence of α-lactalbumin.