Studies on the denaturation of antibody: I. The action of urea on diphtheria antitoxin

Although a great deal of information has been accumulated regarding the stability of antibody under various conditions and treatments (1), the action of urea and similar substamces seems to have been largely neglected. Since the action of urea in denaturing proteins involves weakening the secondary bonds about the peptide linkages (2, 3) it is of interest to know the effect of urea on antibody. Pappenheimer, Lundgren, and Williams (4) report that diphtheria antitoxin is unaffected by "strong" urea solutions. Very recently Erickson and Neurath (5) have reported some experiments on the action of guanidine hydrochloride on horse antipneumococcus antibody. The present investigation of the stability of antibody in urea was undertaken because of the presumable importance of the results to the theory of antibody structure. Diphtheria antitoxin has been chosen as the antibody for study because the accurate neutralization methods available for its determination permit direct measurement of the fundamental property of antibody, its ability to combine with antigen.