1. Oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

 5. Isomerases

   5.1  Racemases and epimerases

   5.2  cis-trans-Isomerases

   5.3  Intramolecular oxidoreductases

   5.4  Intramolecular transferases

   5.5  Intramolecular lyases

   5.6  Isomerases altering macromolecular conformation

     5.6.1  Enzymes altering polypeptide conformation or assembly

     5.6.2  Enzymes altering nucleic acid conformation

       5.6.2.1  DNA topoisomerase

       5.6.2.2  DNA topoisomerase (ATP-hydrolysing)

       5.6.2.3  DNA 5'-3' helicase

       5.6.2.4  DNA 3'-5' helicase

       5.6.2.5  RNA 5'-3' helicase

       5.6.2.6  RNA 3'-5' helicase

       5.6.2.7  DEAD-box RNA helicase

   5.99  Other isomerases

 6. Ligases

 7. Translocases