Which enzyme is active in the stomach and what is its primary substrate?

Which enzyme is active in the stomach and what is its primary substrate?

• A. Pepsin; proteins
• B. Amylase; carbohydrates
• C. Lipase; fats
• D. Trypsin; proteins

Answer: (A)

In the stomach, digestion relies on enzymes that can function in a highly acidic environment. Pepsin is the enzyme active there, produced as pepsinogen by the stomach lining and activated by hydrochloric acid. Once active, pepsin cleaves peptide bonds, beginning the breakdown of proteins. Its primary substrate is proteins. Other options don’t fit because amylase digests carbohydrates and is inactivated by stomach acid, lipase targets fats (with gastric lipase playing a minor role), and trypsin is a pancreatic enzyme that works in the small intestine, not the stomach.

In the stomach, digestion relies on enzymes that can function in a highly acidic environment. Pepsin is the enzyme active there, produced as pepsinogen by the stomach lining and activated by hydrochloric acid. Once active, pepsin cleaves peptide bonds, beginning the breakdown of proteins. Its primary substrate is proteins.

Other options don’t fit because amylase digests carbohydrates and is inactivated by stomach acid, lipase targets fats (with gastric lipase playing a minor role), and trypsin is a pancreatic enzyme that works in the small intestine, not the stomach.