Acid hydrolysis of monoclonal antibodies

For analysis of monoclonal antibodies using polyacrylamide gel electrophoresis, two hydrolytic fragments derived from the heavy chain of mouse IgG1 were produced during incubation of the antibodies in Laemmli reducing sample buffer at 100 degrees C for 5 min. The cleavage sites were identified by amino terminal sequencing. Results indicate that the final pH of the mixture is critical for the production of the fragments which are generated when the pH is approximately 6.0. At pH 8.0, no fragments are detected. The relevance of this finding to those working with monoclonal antibodies is discussed.