Cleavage of human serum immunoglobulin G by an immobilized pepsin preparation

In order to obtain an efficacious and safe immunoglobulin G (IgG) preparation for intravenous use, the digestion of IgG with an immobilized pepsin (EC 3.4.23.1) preparation was studied. Thus, pepsin was immobilized onto glutaraldehyde-activated AH-Sepharose 4B under acidic conditions. The enzymatic properties, such as proteolytic activity, pH-activity profile and heat stability, of the immobilized pepsin preparation were examined. The immobilized pepsin retained more than 40% of its proteolytic activity toward $\text{N-}\text{acetyl-}\text{l}\text{-phenylalanyl-}\text{l}\text{-3,5-diiodotyrosine}$ and more than 30% toward IgG, and also remarkable stability as compared with free pepsin. The immobilized pepsin thus prepared was efficiently used for the limited cleavage of IgG and the gel-filtration effect of the column made it easily possible to yield the F(ab′)₂-rich fraction for intravenous use.