[Effect of D-penicillamine and 2-mercaptoethanol on human IgM in normal serum]

Serum from healthy blood donors (O Rh+) was fractionated on a Sephadex-G-200 column before and after incubation with equal volumes of either 0.2 m 2-Mercaptoethanol or D-Penicillamine. Immunoelectrophoretic analyses revealed that addition of these two sulphhydryl-containing compounds resulted in disappearance of the typical IgM-precipitate within the first peak. A new precipitate specific for M-chains appeared within the second peak. The data indicate that the smaller subunits with M-chain specificity result from splitting of disulphide bonds of the IgM molecules by the D-Penicillamine and the 2-Mercaptoethanol.