[Kinetic study of human immunoglobulin G fragmentation by pepsin].

The rate of pepsin hydrolysis of the four subclasses of human IgG has been studied. The levels of undegraded IgG and of pep-F'c fragments have been determined by radial immunodiffusion using specific antisera against Cgamma2 and Cgamma3 domain antigenic determinants. This study shows that the four IgG subclasses have different susceptibilities to pepsin hydrolysis and defines the optimum conditions (times of hydrolysis) for the preparation of maximum yields of F (ab)'2 fragments and/or pep-F'c fragments.