Proteolysis of rat IgG subclasses by Staphylococcus aureus V8 proteinase

Monoclonal IgG belonging to the four rat IgG subclasses (IgG1, IgG2a, IgG2b, IgG2c) and some IgG subclasses from normal rat serum were subjected to enzymatic degradation with Staphylococcus aureus V8 proteinase. The results show that only one subclass, IgG2b, is significantly cleaved by the enzyme, with the release of two main products identified as F(ab)2 and Fc-like fragments. This unique susceptibility of the IgG2b subclass represents therefore an easy means of identification and also offers a simple procedure for a preparation of F(ab)2 fragments from monoclonal IgG2b antibodies.