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

       5.1.3.1  ribulose-phosphate 3-epimerase

       5.1.3.2  UDP-glucose 4-epimerase

       5.1.3.3  aldose 1-epimerase

       5.1.3.4  L-ribulose-5-phosphate 4-epimerase

       5.1.3.5  UDP-arabinose 4-epimerase

       5.1.3.6  UDP-glucuronate 4-epimerase

       5.1.3.7  UDP-N-acetylglucosamine 4-epimerase

       5.1.3.8  N-acylglucosamine 2-epimerase

       5.1.3.9  N-acylglucosamine-6-phosphate 2-epimerase

       5.1.3.10  CDP-paratose 2-epimerase

       5.1.3.11  cellobiose epimerase

       5.1.3.12  UDP-glucuronate 5'-epimerase

       5.1.3.13  dTDP-4-dehydrorhamnose 3,5-epimerase

       5.1.3.14  UDP-N-acetylglucosamine 2-epimerase (non-hydrolysing)

       5.1.3.15  glucose-6-phosphate 1-epimerase

       5.1.3.16  UDP-glucosamine 4-epimerase

       5.1.3.17  heparosan-N-sulfate-glucuronate 5-epimerase

       5.1.3.18  GDP-mannose 3,5-epimerase

       5.1.3.19  chondroitin-glucuronate 5-epimerase

       5.1.3.20  ADP-glyceromanno-heptose 6-epimerase

       5.1.3.21  maltose epimerase

       5.1.3.22  L-ribulose-5-phosphate 3-epimerase

       5.1.3.23  UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase

       5.1.3.24  N-acetylneuraminate epimerase

       5.1.3.25  dTDP-L-rhamnose 4-epimerase

       5.1.3.-  

     5.1.99  Acting on other compounds

     5.1.-  Racemases and epimerases

   5.2  cis-trans-Isomerases

   5.3  Intramolecular oxidoreductases

   5.4  Intramolecular transferases

   5.5  Intramolecular lyases

   5.99  Other isomerases

   5.-  

 6. Ligases