acetilCoA

Acetyl-CoA is a central metabolite in energy production and biosynthesis. It is the thioester formed when an acetyl group is linked to coenzyme A, via a high-energy bond. The acetyl unit carried by CoA serves as a versatile donor in multiple cellular pathways.

Most acetyl-CoA in animals is produced in mitochondria. The pyruvate dehydrogenase complex converts pyruvate, from glycolysis, into acetyl-CoA, linking glycolysis to the citric acid cycle. Fatty acid beta-oxidation also generates acetyl-CoA within mitochondria, while amino acids classified as ketogenic can feed into acetyl-CoA formation. Because acetyl-CoA cannot readily cross the inner mitochondrial membrane, cytosolic acetyl-CoA is typically generated from exported citrate, which is cleaved back to acetyl-CoA and oxaloacetate by ATP citrate lyase.

In the citric acid cycle, acetyl-CoA condenses with oxaloacetate to form citrate, yielding NADH and FADH2 for the electron transport chain. Acetyl-CoA is also a substrate for biosynthetic processes, including fatty acid and cholesterol synthesis in the cytosol, ketone body production in the liver, and various acetylation reactions that modify proteins and other molecules.

Regulation occurs at several levels, notably the pyruvate dehydrogenase complex, which is inhibited by high NADH, ATP, and acetyl-CoA and activated by specific phosphatases. The synthesis of CoA requires pantothenic acid (vitamin B5), and acetyl-CoA serves as a key link between energy production and macromolecule synthesis across cell types.