Coenzyme A

Coenzyme A (CoA, CoASH, or HSCoA) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle. It is adapted from cysteamine, pantothenate, and adenosine triphosphate.

Biosynthesis
Coenzyme A is synthesized in a five-step process from pantothenate:
 * 1) Pantothenate is phosphorylated to 4'-phosphopantothenate by the enzyme pantothenate kinase
 * 2) A cysteine is added to 4'-phosphopantothenate by the enzyme phosphopantothenoylcysteine synthetase to form 4'-phospho-N-pantothenoylcysteine (PPC)
 * 3) PPC is decarboxylated to 4'-phosphopantetheine by phosphopantothenoylcysteine decarboxylase
 * 4) 4'-phosphopantetheine is adenylylated to form dephospho-CoA by the enzyme phosphopantetheine adenylyl transerase
 * 5) Finally, dephospho-CoA is phosphorylated using ATP to coenzyme A by the enzyme dephosphocoenzyme A kinase.

Function
Since coenzyme A is chemically a thiol, it can react with carboxylic acids to form thioesters, thus functioning as an acyl group carrier. It assists in transferring fatty acids from the cytoplasm to mitochondria. A molecule of coenzyme A carrying an acetyl group is also referred to as acetyl-CoA. When it is not attached to an acyl group it is usually referred to as 'CoASH' or 'HSCoA'.

List of coenzyme A activated acyl groups

 * Acetyl-CoA
 * Propionyl-CoA
 * Acetoacetyl-CoA
 * Coumaroyl-CoA (used in flavonoid and stilbenoid biosynthesis)
 * Acyl derived from dicarboxylic acids
 * Malonyl-CoA
 * Succinyl-CoA
 * Hydroxymethylglutaryl-CoA (used in isoprenoid biosynthesis)
 * Pimelyl-CoA (used in biotin biosynthesis)


 * Butyryl CoA