1. Oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

 5. Isomerases

   5.1  Racemases and epimerases

   5.2  cis-trans-Isomerases

     5.2.1  cis-trans Isomerases (only sub-subclass identified to date)

       5.2.1.1  maleate isomerase

       5.2.1.2  maleylacetoacetate isomerase

       5.2.1.4  maleylpyruvate isomerase

       5.2.1.5  linoleate isomerase

       5.2.1.6  furylfuramide isomerase

       5.2.1.8  peptidylprolyl isomerase

       5.2.1.9  farnesol 2-isomerase

       5.2.1.10  2-chloro-4-carboxymethylenebut-2-en-1,4-olide isomerase

       5.2.1.12  zeta-carotene isomerase

       5.2.1.13  prolycopene isomerase

       5.2.1.14  beta-carotene isomerase

   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