FRAGMENTATION OF IMMUNOGLOBULIN DURING STORAGE

Abstract

Solutions of human γ-globulin undergo changes on storage resulting in the formation of fragments similar to those produced by the digestion of human γ-globulin with the enzymes papain and plasmin. Two fragments have been isolated from the naturally fragmented material which resemble the Fab and Fc fragments resulting from digestion by papain. The fragments have been characterized on starch gel, by amino acid analysis, and in the ultracentrifuge, and appear to be identical with similar fragments isolated from plasmin digests of human γ-globulin. The natural Fc-like fragment differs from the papain Fc fragment but the Fab fragments from the three sources appear to be identical. Like the papain Fab fragment, the naturally occurring and plasmin-induced Fab fragments have antibody activity.