Structural studies of three IgG kappa proteins from a patient with multiple myeloma

Three distinct IgG proteins of similar concentration and the same light-chain type were demonstrated in a myeloma serum. The bonds between the heavy and light chains were split, and the isolated gamma- and kappa-chains were characterized by crossed immunoelectrophoresis, subgroup determination and N-terminal amino acid sequence. The studies showed that the IgG heterogeneity was due to differences in the primary structure of the variable parts of the kappa-chains. Two of the kappa-chains belonged to subgroup V kappa I, and one chain, the most anodic one, belonged to V kappa III The gamma-chains were homogeneous and belonged to subgroup VHIII.