Epimerase and racemase

The epimerases are enzymes and are among the subgroup of isomerases. In the structure transformation of organic molecules often epimers play a role. Epimers are molecules that differ only in the asymmetrical arrangement of the substituents on a carbon atom. Epimerases are enzymes thus may alter the three-dimensional arrangement of the four different substituents on this carbon atom ( = stereocenter ).

Examples

• UDP glucose ↔ UDP-galactose ( enzyme: UDP-glucose 4-epimerase )