Pantothenic acid is made up of two units—pantoic acid and β-alanine—which are joined together by a peptide linkage. A-form pantothenate occurs in a series of reactions. Pantothenate is first phosphorylated, to which cysteine is added. Decarboxylation followed by addition of AMP moiety and a phosphate results in coenzyme A. The structure of coenzyme A or CoA (A for acetylation) consists of pantothenic acid joined to β-mercaptoethylamine on one end. On the other side, pantothenic acid is held by a phosphate bridge to adenylic acid, which is made up of adenine, and a phosphate linked to carbon-3 of ribose.