Studies on the optimum pH for the action of pepsin on "native" and denatured bovine serum albumin and bovine hemoglobin.

Several studies (2-6) of the hydrolysis of proteins by proteolytic eneymes have led to the suggestion that only denatured forms of the substrate are acted on; and that where an equilibrium between native (N) and denatured (D) forms, N $ D, is not spontaneous, the initial action of a protease may be a nonhydrolytic denaturation of native substrate. Green and Neurath (7) have suggested that native as well aa denatured proteins can serve as protease substrates, a view also held by Chernikov (8). A simplified version of the scheme proposed by Green and Neurath to depict these ideas is shown below,