cholesterylesters

Cholesteryl esters are a class of lipids formed by the esterification of cholesterol with a fatty acid. In this reaction, the hydroxyl group of cholesterol at the C3 position reacts with the carboxyl group of a fatty acid to form an ester linkage and release a molecule of water. This process is typically catalyzed by an enzyme called acyl-CoA:cholesterol acyltransferase (ACAT) in cells, or lecithin-cholesterol acyltransferase (LCAT) in the blood plasma.

Cholesteryl esters are significantly more hydrophobic than free cholesterol. This property makes them an efficient way to store cholesterol within cells and in lipid droplets. They are a major component of lipoproteins, such as low-density lipoprotein (LDL) and high-density lipoprotein (HDL), which are responsible for transporting lipids throughout the body. In HDL particles, LCAT esterifies cholesterol picked up from peripheral tissues, facilitating its transport back to the liver for excretion.

In the body, cholesteryl esters serve as a reservoir of both cholesterol and fatty acids. When the body requires cholesterol, the ester bond can be hydrolyzed by enzymes like cholesteryl ester hydrolase (CEH) to release free cholesterol. This free cholesterol can then be used for various cellular functions, such as membrane synthesis or steroid hormone production. High levels of cholesteryl esters, particularly within LDL particles, are associated with an increased risk of atherosclerosis.