Amino acid sequence of rabbit light chains: variable region of a light chain from a homogeneous immunoglobulin raised by streptococcal immunization.

The variable region sequence has been determined for the light chain (L) from a rabbit homogeneous immunoglobulin (3547) produced by immunization with group A streptococcal vaccine. Unlike most immunoglobulins produced by these vaccines, this immunoglobulin had no binding activity for the group A polysaccharide nor for any of a wide range of streptococcal cell components tested, nor did it have binding activity for rabbit IgG. Tryptic digestion of the citraconylated L chain and acid hydrolysis of the aspartyl-proline bond at positions 109-110 were used to obtain two variable region peptides comprising residues 1-61 and 62-109, respectively. Automated sequence analysis of these peptides and the peptides obtained from them by complete tryptic digestion gave sequence data for the entire L-chain variable (V) region. Comparison of the 3547 L chain V region sequence with other data supports the observations that only two hypervariable regions are present in rabbit kappa chains and that the hypervariable region beginning at residue 90 may vary in length by as much as six residues.