Studies on the Mechanism of Activation of Pepsinogen

Experiments were carried out on the effects of substrate or competitive inhibitor on the rate of appearance of N-terminal isoleucine residue of pepsin and peptides released from pepsinogen in its conversion to pepsin. Assumptions were made from these experiments, that an active site is initially formed in pepsinogen by acidification of its solution, and that peptide bond between 41-glutamyl and 42-isoleucyl residues locates in the juxtaposition to the active site forming an intramolecular enzyme-substrate complex. Thus, N-terminal tail of pepsinogen is released by a hydrolysis catalyzed by its own active site.

It was Indeed ascertained in this study that neither a small amount of pepsin which could be accompanied by pepsinogen preparation used contributes to the initial step of hydrolysis of pepsinogen nor pepsin formed accelerates the following activation process.

Therefore, it was concluded that the conversion of pepsinogen to pepsin is self-degrad-ation process.