Which of the following is the autocatalytic cleavage enzyme?

T is secreted by the chief cells of stomach as inactive pepsinogen. The conversion of pepsinogen to pepsin is brought about by removal of 44 amino acids from the N-terminal end, by the hydrochloric acid. The optimum pH for activity of pepsin is around 2. Pepsin is an endopeptidase, (Table 14.1). Pepsin catalyzes the hydrolysis of the bonds formed by carboxyl groups of Phe, Tyr, Trp, and Met. By the action of pepsin, proteins are broken into proteoses and peptones.Ref: DM Vasudevan, Page no: 171