Acetoin racemase  In enzymology, an acetoin racemase () is an enzyme that catalyzes the chemical reaction  This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on hydroxy acids and derivatives. The systematic name of this enzyme class is acetoin racemase. This enzyme is also called acetylmethylcarbinol racemase. This enzyme participates in butanoate metabolism.