The mechanism of activation of pepsinogen was studied. It was found that no peptide bond cleavage occurred in the molecule of denatured pepsinogen at pH 2. It was inferred from this that a specific secondary and tertiary structure is formed in the molecule of pepsinogen in acid and that it might be necessary for the hydrolysis of the peptide bond. From the circular dichroism studies on pepsinogen and pepsin, it was found that there is a conformational change in the molecule of pepsinogen at pH 4.3~4.5 and that this change is followed by a gradual formation of pepsin.
Köster, U. (2001). How to produce intense and pure ISOL beams. Progress in Particle and Nuclear Physics, 46(1), 411–412. https://doi.org/10.1016/S0146-6410(01)00148-X