MEDICAL PHYSIOLOGY

Detailed explanation-1: -Pepsin is a stomach enzyme that serves to digest proteins found in ingested food. Gastric chief cells secrete pepsin as an inactive zymogen called pepsinogen. Parietal cells within the stomach lining secrete hydrochloric acid that lowers the pH of the stomach. A low pH (1.5 to 2) activates pepsin.

Detailed explanation-2: -Protein digestion occurs as a result of the hydrolysis of the peptide bonds that bind the individual amino acids in the polypeptide chain. These reactions are catalyzed by enzymes called proteases.

Detailed explanation-3: -Introduction. During food digestion, proteins are hydrolysed into polypeptides and ultimately down to single amino acids, prior to absorption into the bloodstream. The first protease that catalyses the hydrolysis of these intact proteins is pepsin, which is secreted in the stomach.

Detailed explanation-4: -Pepsin cleaves peptide bonds in the amino-terminal side of the cyclic amino acid residues (tyrosine, phenylalanine, and tryptophan), breaking the polypeptide chains into smaller peptides (Fange and Grove, 1979).