RULE OF ANTIBODY STRUCTURE - PRIMARY STRUCTURE OF A HUMAN MONOCLONAL IGAL-IMMUNOGLOBULIN (MYELOMA PROTEIN TRO) .5. ARRANGEMENT OF TRYPTIC PEPTIDES AND A DISCUSSION OF COMPLETE PRIMARY STRUCTURE OF H-CHAIN

Abstract

The sequence work done with tryptic and chymotryptic peptides and some cyanogen bromide splitting products was presented. With these peptides, and if necessary with their splitting peptides, the whole primary structure of the .alpha.1-H chain of myeloma protein Tro is established. The position of the amides is determined by electrophoresis and digestion with aminopeptidase M. The .alpha.1-chain Tro comprises 475 amino acid residues. Because of its specific exchanges and deletions the variable part of .alpha.1-chain Tro belongs to subgroup III of variable parts of H chains. The switch from the variable to the constant part occurs at position 119/120 and is analogous to other chains which were sequenced up to now. The large number of cysteine residues in the .alpha.-chain which may influence the tertiary structure, especially in the hinge and the subsequent CH2[H chain constant region 2]region, is noteworthy. Myeloma protein Tro is compared with the other .alpha.1-chain Bur sequenced in the meantime, and protein But, which is an Ig[immunoglobulin]A2 molecule of the allotype A2m(2).