GENERAL HISTOLOGY

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: -Pepsin is active in acidic pH like that in the gastric portion and can hydrolyze several proteins, except for mucins, spongins, conchiolin, keratin, or low molecular weight peptides (Sumner and Somers, 1947 apud Fange and Grove, 1979).

Detailed explanation-3: -Pepsin is an aspartic protease that acts in food digestion in the mammal stomach. An optimal pH of around 2 allows pepsin to operate in its natural acidic environment, while at neutral pH the protein is denatured.

Detailed explanation-4: -The reason pepsin functions best at pH 2 is because the carboxylic acid group on the amino acid in the enzyme’s active site must be in its protonated state, meaning bound to a hydrogen atom. At low pH the carboxylic acid group is protonated, which allows it to catalyze the chemical reaction of breaking chemical bonds.

Detailed explanation-5: -Effect of pH on substrate hydrolysis by pepsin This observation is as expected since the optimal pH for pepsin’s proteolytic activity is 1.6, and is consistent with the observation that pepsin optimally degrades dietary proteins between a pH range of 1.2 to 2.5 [26, 27].