Antigenic structure of sperm whale myoglobin. I. Partition of specificities between antibodies reactive with peptides and native protein.

We have resolved anti-sperm whale Mb antibodies into two distinct populations: One population is reactive only with the native molecule, and the second is reaction with both Mb and peptide fragments. CNBr cleavage of sperm whale Mb yields three peptides: peptide I (1-55), peptide II (56-131), and peptide III (132-153). Immunoadsorbent columns made with these three peptides were used to fractionate antibody to sperm whale Mb. These columns cumulatively bind 60 to 70% of the total antibody present in the four sera studied (the amount of antibody bound by each peptide was proportional to its size). The remaining 30 to 40% of antibody could only bind specifically to an immunoadsorbent column of native Mb. This result indicates that not all antigenic determinants on the native Mb molecule are represented on peptide fragments.