STRUCTURAL STUDIES OF IMMUNOGLOBULINS .3. SUSCEPTIBILITY OF HUMAN GAMMAG GLOBULINS TO PEPTICHYDROLYSIS AND PAPAIN SENSITIVITY OF F(AB')2 FRAGMENTS

Peptic proteolysis of human γG globulins at pH 4·2 was found to result in the formation of a bivalent fragment analogous with the rabbit F(ab′)2. This fragment is split into monovalent fragments by reductive treatment. Evidence is presented on the heterogeneity of human γG globulins with respect to peptic susceptibility. The F(ab′)2 fragments of papain resistant and papain sensitive γG globulins were found to retain the resistance or sensitivity to papain characteristic of the corresponding intact protein. © 1969.