Coenzymes and catalysis

The role that the coenzyme pyridoxyl phosphate plays in the metabolism of amino acids is an example of the role that coenzymes play in catalysis. In this reaction the coenzyme (pyridoxal phosphate) and the amino acid histidine (substrate) both bind to the active site of the enzyme, histidine decarboxylase which, as the name indicates in involved in the removal of carbon dioxide from histidine.

Catalysis occurs in a number of steps involving the enzyme, substrate and coenzyme as seen in the next figure.