Triacylglycerol lipase is a hormonally regulated enzyme (Figure 18.11) that catalyzes the hydrolytic release of fatty acid from carbon 1 or 3 of the glycerol moiety. The fatty acid release is followed by the action of a diacylglycerol lipase and a monoacylglycerol lipase, in turn.

Together these three enzymes degrade the original molecule to glycerol and three unesterified fatty acids. In adipose tissue, the primary hormonal effects are mediated by epinephrine in stress situations and by glucagon during fasting.