Which enzyme digests fats in the pancreas, and what aids its activity at the lipid-water interface?

• A. Pancreatic amylase; glucose
• B. Chymotrypsin; bile acids
• C. Pancreatic lipase; bile salts and colipase
• D. Trypsin; enterokinase

Answer: (C)

Fat digestion in the small intestine is carried out by pancreatic lipase, which acts on triglycerides at the lipid–water interface formed when fats are emulsified. To work effectively at this interface, lipase relies on two helpers: bile salts and colipase. Bile salts emulsify dietary fats, increasing surface area for the enzyme to act, but they can also displace lipase from the surface. Colipase binds to pancreatic lipase and anchors it to the lipid surface, allowing the enzyme to function despite the presence of bile salts. Colipase is secreted with lipase and activated in the intestine by trypsin. So the correct pairing is pancreatic lipase with bile salts and colipase, which together enable fat digestion at the interface.