Kolesteroliesteröityä

Kolesteroliesteröityä, or cholesterol esterification, is a crucial metabolic process in which cholesterol is converted into a cholesterol ester. This transformation involves the enzymatic addition of a fatty acid to the hydroxyl group of cholesterol. The primary enzyme responsible for this reaction is acyl-CoA:cholesterol acyltransferase (ACAT), also known as sterol O-acyltransferase (SOAT). Cholesterol esters are more hydrophobic than free cholesterol, meaning they are less soluble in water. This property makes them ideal for storage within cells, particularly in lipid droplets, and for packaging into lipoproteins for transport in the bloodstream.

The esterification of cholesterol plays a vital role in various physiological functions. In the liver, it facilitates the packaging of cholesterol into very-low-density lipoproteins (VLDL) and high-density lipoproteins (HDL), which are essential for cholesterol transport throughout the body. Adipose tissue also esterifies cholesterol for storage. In steroidogenic tissues, such as the adrenal glands and gonads, cholesterol esterification is a key step in the synthesis of steroid hormones. Furthermore, cholesterol esterification is important for the absorption of dietary cholesterol in the intestine. The process is reversible, with cholesterol ester hydrolase (CEH) catalyzing the hydrolysis of cholesterol esters back into free cholesterol and a fatty acid when needed. Imbalances in cholesterol esterification and de-esterification can contribute to various health conditions, including atherosclerosis.