Effect of mercaptans and other agents on the human complement component beta-1c-globulin.

Immunoelectrophoretic analyses and complement titrations of whole human serum show that a number of physical, chemical and immunological agents affect the β/β-globulin system which is considered to represent the third component of complement (C′). The transformation from β-globulin to β-globulin is the normal result of ageing, while antigen-antibody complexes, polylysine, hydrazine and cobra venom accelerate this change. In addition, α-globulin fragments of β-globulin appear after interaction of normal sera with antigen-antibody complexes, treatment with cobra venom, and by storage under nitrogen in glass tubes or in polyethylene containers. Similar α-fragments are seen in the aged sera of some patients with glomerulonephritis or renal allografts. With prolonged storage these α-fragments can reform β-globulin. On the other hand, 2-mercaptoethanol and penicillamine produce complete dissolution of β-globulin into rapidly migrating, poorly defined fragments in the α-globulin and albumin regions, and transform β-globulin into a stable β-globulin. The reduced fragments of β-globulin, if not alkylated, can subsequently form the β-globulin, but not the β-globulin. These results indicate that β-globulin is composed of several subunits, some of which are joined by disulphide bonds, but that the α-globulin fragments seen in some pathological sera are not a result of disulphide bond reduction.