Lipases, a family of enzymes, break down triglycerides into glycerol and free fatty acids. Lipases are expressed and active in multiple tissues; for instance, hormone-sensitive lipases are in adipocytes, hepatic lipases are in the liver, pancreatic lipase is in the small intestine, and lipoprotein lipase is in the vascular endothelial surface. Lipases in pancreatic secretions play role in digestion and hydrolysis of fat and absorption of fat-soluble vitamins. Understanding the lipase function is vital for the pathophysiology of fat necrosis and chronic and acute pancreatitis. Lipases also play a critical role in the mechanism of some cholesterol-lowering medications.

Molecular Level

Lipase belongs to the alpha/beta-hydrolase fold superfamily of enzymes. They function by employing chymotrypsin-like hydrolysis, which utilizes a histidine base, an aspartic acid and serine nucleophile.

Function

Lipase is an enzyme which breaks down triglycerides into glycerol and free fatty acids by catalyzing the hydrolysis of the ester bonds in triglycerides. These are present in pancreatic secretions and participate in fat digestion and metabolism. Lipases play an essential role in lipid transport and serve individual functions in several tissues including hormone-sensitive lipases in the adipocytes, hepatic lipase in the liver, pancreatic lipase in the small intestine, and lipoprotein lipase in the endothelial cells.

Hepatic lipases in the liver degrade the triglycerides that stay in intermediate-density lipoprotein (IDL). Hormone-sensitive lipase is found within fat tissue and is accountable for hydrolyzing the triglycerides accumulated within adipocytes. Lipoprotein lipase can be found in the vascular endothelial cells and is accountable for degrading triglycerides that circulate from chylomicrons and very low-density lipoproteins (VLDLs). Pancreatic lipase can be found within the small intestine and is indulged in degrading dietary triglycerides.

The LDL ultimately serves up to transport cholesterol from the liver to peripheral tissue. Hepatic lipase plays an essential role in developing and delivering low-density lipoprotein (LDL). The LDL is created by modifying the IDL in the peripheral tissue and liver by hepatic lipase. These LDL particles are in use, or endocytosed, through receptor-mediated endocytosis by target cell tissue. The LDL ultimately serves up to transfer cholesterol from the liver to peripheral tissue.