Acetyl-CoA

Acetyl-CoA is a coenzyme-bound two-carbon acetyl group that supplies carbon to pathways including the citric acid cycle, fatty acid synthesis, and ketone-body production.

Coenzyme A: Coenzyme A is a carrier molecule that transfers acyl groups in metabolic reactions. It is the carrier portion of acetyl-CoA and provides the reactive thiol.
Acetyl group: An acetyl group is a two-carbon acyl group with the structure CH₃CO–. It is the carbon unit carried by acetyl-CoA.
Fatty acid synthesis: Fatty acid synthesis is the pathway that builds fatty acids from acetyl-derived two-carbon units. Acetyl-CoA supplies the starting carbon, largely after conversion to malonyl-CoA.
Citrate shuttle: The citrate shuttle transfers mitochondrial acetyl units to the cytosol in the form of citrate. Acetyl-CoA itself cannot cross the inner mitochondrial membrane, so this route supplies cytosolic synthesis.
Thioester: A thioester is a compound containing a carbonyl group bonded to sulfur. Acetyl-CoA’s thioester bond makes acetyl transfer energetically favorable.
Pantothenic acid: Pantothenic acid, or vitamin B5, is a nutrient used to synthesize coenzyme A. Its atoms contribute to the coenzyme portion of acetyl-CoA.
Ketogenesis: Ketogenesis is the production of ketone bodies from acetyl-CoA, mainly in liver mitochondria. When carbohydrate availability is low, excess acetyl-CoA can be diverted into ketone bodies.
Malonyl-CoA: Malonyl-CoA is a three-carbon coenzyme A derivative used in fatty acid synthesis and regulation of fatty acid oxidation. It is produced from acetyl-CoA and helps prevent simultaneous fatty acid synthesis and breakdown.
Citric acid cycle: The citric acid cycle is a sequence of reactions that oxidizes acetyl groups and captures energy in cells. It accepts acetyl-CoA to begin oxidation of the acetyl group.
Pyruvate dehydrogenase complex: The pyruvate dehydrogenase complex converts pyruvate into acetyl-CoA, carbon dioxide, and NADH. It makes acetyl-CoA from glucose-derived pyruvate.

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