1. Oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

 5. Isomerases

   5.1  Racemases and epimerases

     5.1.1  Acting on amino acids and derivatives

     5.1.2  Acting on hydroxy acids and derivatives

     5.1.3  Acting on carbohydrates and derivatives

     5.1.99  Acting on other compounds

       5.1.99.1  methylmalonyl-CoA epimerase

       5.1.99.2  16-hydroxysteroid epimerase

       5.1.99.3  allantoin racemase

       5.1.99.4  alpha-methylacyl-CoA racemase

       5.1.99.5  hydantoin racemase

       5.1.99.6  NAD(P)H-hydrate epimerase

       5.1.99.7  dihydroneopterin triphosphate 2'-epimerase

       5.1.99.8  7,8-dihydroneopterin epimerase

   5.2  cis-trans-Isomerases

   5.3  Intramolecular oxidoreductases

   5.4  Intramolecular transferases

   5.5  Intramolecular lyases

   5.6  Isomerases altering macromolecular conformation

   5.99  Other isomerases

 6. Ligases

 7. Translocases