Simplified preparation of rabbit Fab fragments

Papain attached to solid-phase CH-Sepharose 4B was used to digest rabbit IgG. Protein A-Sepharose CL-4B was used to remove undigested IgG and Fc fragments. Pure Fab fragments free of IgG, Fc fragments and papain were readily obtained by this procedure with a yield of about 75%. Polyacrylamide gel electrophoresis of the Fab in the presence of sodium dodecyl sulphate gave a single band under both reducing and non-reducing conditions. The molecular weight of the Fab determined by sedimentation equilibrium was 49,200. Unlike the IgG, the Fab obtained did not form precipitin lines when used in immunoelectrophoresis.