Which enzyme helps in the digestion of proteins in the stomach?

Pepsin is the enzyme responsible for the digestion of proteins in the stomach. It is secreted by the gastric lining in an inactive form called pepsinogen. Once in the acidic environment of the stomach, pepsinogen is activated to pepsin, which then breaks down proteins into smaller peptides.

Pepsin is particularly important because it functions optimally in the highly acidic conditions of the stomach, unlike other enzymes that may function in the more neutral pH of the small intestine. This specificity allows the stomach to efficiently begin the process of protein digestion before the proteins are further broken down by enzymes such as trypsin and chymotrypsin in the intestine. These latter enzymes, although also involved in protein digestion, operate in the small intestine rather than the stomach.

Catalase, on the other hand, is not involved in protein digestion at all; it is an enzyme that catalyzes the breakdown of hydrogen peroxide into water and oxygen.