Preparation of F(ab')2 fragments from mouse IgG of various subclasses.

We have investigated the effects of peptic digestion on mouse monoclonal immunoglobulins of each subclass of IgG. F(ab')2 fragments were obtained in good yield from IgG1, IgG2a and IgG3 proteins. The relative rates of digestion were IgG3 greater than IgG2a greater than IgG1. Variations in rate of digestion were noted for individual monoclonal IgG3 proteins. Five different IgG2b proteins were degraded very rapidly without the detectable formation of antigen-binding F(ab')2 fragments. One IgG1 protein out of four tested was also rapidly degraded.