It is generally known that Proteins are denatured when placed in a low pH (acidic) environment. However, in our stomach, the enzyme pepsin (which is also a protein) is not denatured despite the very acidic environment attributed to hydrochloric acid (HCl). What could be the possible reason for this?

Answer: [D] Pepsin is secreted in a different form in stomach

The correct answer is D. We should know that Pepsin is secreted in its precursor form (pepsinogen). Pepsinogen is secreted into the lumen of the stomach. This is the precursor form of pepsin. Hydrochloric acid found within the stomach will hydrolyze pepsinogen. Pepsin will be formed from pepsinogen (after hydrolysis). Only then can pepsin perform its job to breakdown food particles (particularly protein in food) in the stomach.

This question is a part of GKToday's Integrated IAS General Studies Module