Common peptides from the N-terminal half of heavy chain of immunoglobulin G from normal rabbit serum and a specific antibody.

Fragment C-1, the N-terminal half of the heavy chain of rabbit immunoglobulin G, was prepared by cyanogen bromide cleavage from the heavy chain of immunoglobulin G obtained both from the pooled serum of normal rabbits and from specific anti-dinitrophenyl antibody. Tryptic digestion of fragment C-1 after the lysine residues had been allowed to react with S-ethyl trifluorothioacetate led to the isolation of six peptides from inert immunoglobulin G and specific antibody that appear to account for most of this section of the heavy chain. This approach should make possible comparative sequence studies of the Fd section of the heavy chain from different allotypes and from specific antibodies.