Phylogeny of immunoglobulin structure and function. XIV. Peptide map and amino acid composition studies of shark antibody light chains.

Light chains from antibodies to the streptococcal A-variant carbohydrate from individual nurse sharks were compared by peptide maps of tryptic digests and amino acid compositions. Although the amino acid compositions of the different chains were quite similar, considerable differences as well as similarities were demonstrable on peptide maps. The peptide maps were interpreted as indicating that shark L chains likely have constant and variable regions as seen in the immunoglobulins of higher animals. Furthermore the unique peptides characteristic of different L chains support the hypothesis that nurse sharks, as a species, possess a relatively large number of different L chain amino acid sequences which are compatible with antibody binding sites to the streptococcal antigen. Hence the repetoire of nurse shark antibody combining sites to this antigen appears to be quite extensive.