Amino Acid Sequence of Human λ Chains: II. CHYMOTRYPTIC PEPTIDES AND SEQUENCE OF PROTEIN Ha

Abstract

Abstract The primary structure of the variable region of the human λ Bence-Jones Protein Ha has been determined by sequence analysis of the tryptic and chymotryptic peptides; the primary structure of the constant region has been deduced by partial sequence analysis of these peptides and by homology. Twenty-nine chymotryptic peptides covering all but eight of the total of 217 residues were isolated from the carboxymethylated protein. The complete sequence was determined for 14 chymotryptic peptides; of these, nine are in the variable region and five are in the constant region. For the remaining peptides only the partial sequence or the amino acid composition and the end groups were obtained. These results permitted the ordering of all of the tryptic peptides. Of the 15 chymotryptic peptides from the variable region, only a tripeptide was identical with any previously reported for human λ chains. Most of the chymotryptic peptides of the constant region appeared identical with those previously reported for the human λ chain, Protein Sh. No evidence was obtained for variation in sequence of the last 105 residues, but the variable region differed in from 29 to 54 residues from others previously reported.