coenzymeA

Coenzyme A, often abbreviated as CoA, is a vital molecule found in all living organisms. It plays a crucial role in metabolism, particularly in the synthesis and oxidation of fatty acids, and in the citric acid cycle. CoA is a thiol, meaning it contains a sulfhydryl (-SH) group. This functional group is key to its reactivity, as it readily forms thioester bonds with acyl groups, effectively transferring them within biochemical reactions.

The primary function of coenzyme A is to act as a carrier of acyl groups. It is most famously associated with the acetyl group, forming acetyl-CoA. Acetyl-CoA is a central intermediate in cellular respiration, linking glycolysis and fatty acid breakdown to the citric acid cycle. In this cycle, acetyl-CoA is oxidized to produce ATP, the cell's main energy currency. Beyond energy metabolism, CoA is also essential for the synthesis of numerous important biomolecules, including cholesterol, steroid hormones, neurotransmitters like acetylcholine, and heme.

The synthesis of coenzyme A is a multi-step process that begins with the amino acid cysteine. It involves the addition of pantothenic acid (vitamin B5) and an adenosine triphosphate molecule. Pantothenic acid is a dietary requirement for humans, as it is a precursor to CoA. Deficiencies in vitamin B5 can lead to impaired CoA synthesis, affecting various metabolic pathways. The widespread importance of CoA in cellular processes highlights its fundamental role in life.