Partial amino acid sequence in the N-terminal region of an anti-pneumococcal immunoglobulin heavy chain of allotype a2

Abstract
The amino acid sequence of the N-terminal 48 residues of the heavy chain derived from a homogeneous rabbit antibody to type III pneumococci is described. This chain of allotype a2 is compared with other rabbit heavy chains of allotypes a1, a2 and a3. Within the N-terminal 25 positions, two chains which carry the same allotype a2 possess identical amino acid sequences, but differ markedly from heavy chains of allotypes a1 and a3. Sequence variability is observed in residues 26–27 and 30–34, but not in residues 35–48.