Proteins in multiple myeloma. VI. Cryoglobulins

Abstract

Eight cryoglobulins (abnormal human plasma globulins that have diminished solubility in the cold) have been investigated by means of the analytical ultracentrifuge, electrophoresis, N-terminal amino acid analysis, and serological classification. Although no systematic correlation among the physical constants, amino end groups, and antigenic type was apparent, all the cryoglobulins but one were closely related to normal human γ-globulin. The cryoglobulins differed most notably from normal γ-globulin and from each other in the nature of their amino end groups. In the N-terminal position, three proteins had essentially only aspartic acid, three essentially only glutamic acid, and two had both dicarboxylic acids. The hypothesis is suggested that cryoglobulins are truly unnatural proteins formed only in disease.