In enzymology , an UDP-N-acetylglucosamine 2-epimerase ( EC 5.1.3.14 ) is an enzyme that catalyzes the chemical reaction UDP-N-acetyl-D-glucosamine UDP-N-acetyl-D-mannosamine Hence, this enzyme has one substrate , UDP-N-acetyl-D-glucosamine , and one product , UDP-N-acetyl-D-mannosamine . This enzyme belongs to the family of isomerases , specifically those racemases and epimerases acting on