Structural Studies of Three IgG K Proteins from a Patient with Multiple Myeloma

Abstract

Three distinct IgG proteins of similar concentration and the same light-chain type were demonstrated in a [human] 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 IgG heterogeneity was apparently due to differences in the primary structure of the variable (V) 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.