Which enzyme hydrolyzes triglycerides in circulating lipoproteins?

• A. Lipoprotein Lipase
• B. Hormone-Sensitive Lipase
• C. Pancreatic Lipase
• D. Amylase

Answer: (A)

Triglycerides in circulating lipoproteins are hydrolyzed by lipoprotein lipase, an enzyme anchored to the capillary endothelium in tissues like muscle and adipose tissue. It acts on the triglycerides carried in chylomicrons and VLDL in the bloodstream, cleaving them to release free fatty acids that nearby tissues can take up for energy or storage. This reaction is driven by apolipoprotein C-II on the lipoproteins, which activates LPL. The other enzymes don’t target circulating lipoprotein triglycerides: hormone-sensitive lipase works on stored triglycerides inside adipocytes, pancreatic lipase digests dietary fats in the intestinal lumen, and amylase breaks down starch.