Atsetaatkoensüüm

Atsetaatkoensüüm, often abbreviated as acetyl-CoA, is a crucial molecule in cellular metabolism. It acts as a central hub, linking the breakdown of carbohydrates, fats, and proteins to the citric acid cycle and fatty acid synthesis. Atsetaatkoensüüm is formed when a two-carbon acetyl group is attached to the carrier molecule coenzyme A. This acetyl group typically originates from the breakdown of pyruvate, a product of glycolysis, or from the oxidation of fatty acids. The thioester bond between the acetyl group and coenzyme A is a high-energy bond, making acetyl-CoA a reactive intermediate.

In aerobic respiration, acetyl-CoA enters the citric acid cycle (also known as the Krebs cycle) where its acetyl group is completely oxidized to carbon dioxide, generating ATP, NADH, and FADH2. These electron carriers then proceed to the electron transport chain to produce a large amount of ATP. Additionally, acetyl-CoA is the building block for the synthesis of fatty acids, cholesterol, and other important lipids. The balance of acetyl-CoA levels is tightly regulated, influencing both energy production and biosynthesis pathways. Its central role makes it indispensable for the survival and function of virtually all living organisms.