Which enzyme hydrolyzes chylomicron triglycerides into monoglycerides and free fatty acids?

• A. Hepatic lipase
• B. Endothelial lipase
• C. Lipoprotein lipase
• D. CETP

Answer: (C)

Lipoprotein lipase is the enzyme that acts on triglycerides carried in chylomicrons and VLDL within capillaries, breaking them down into monoglycerides and free fatty acids for uptake by tissues. This enzyme sits on the luminal surface of endothelial cells, especially in adipose tissue and muscle, and requires apolipoprotein C-II as a cofactor to become active. The fatty acids released are taken up by nearby cells for energy or storage, and the chylomicron remnants are cleared by the liver. The other enzymes serve different roles: hepatic lipase mainly acts on triglycerides in IDL/HDL, endothelial lipase targets HDL phospholipids and triglycerides, and CETP transfers cholesteryl esters between lipoproteins rather than hydrolyzing triglycerides. So the enzyme responsible for hydrolyzing chylomicron triglycerides in capillaries is lipoprotein lipase.