1. Oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

 5. Isomerases

 6. Ligases

   6.1  Forming carbon-oxygen bonds

   6.2  Forming carbon-sulfur bonds

   6.3  Forming carbon-nitrogen bonds

   6.4  Forming carbon-carbon bonds

     6.4.1  Ligases that form carbon-carbon bonds (only sub-subclass identified to date)

       6.4.1.1  pyruvate carboxylase

       6.4.1.2  acetyl-CoA carboxylase

       6.4.1.3  propionyl-CoA carboxylase

       6.4.1.4  methylcrotonoyl-CoA carboxylase

       6.4.1.5  geranoyl-CoA carboxylase

       6.4.1.6  acetone carboxylase

       6.4.1.7  2-oxoglutarate carboxylase

       6.4.1.8  acetophenone carboxylase

       6.4.1.9  coenzyme F430 synthetase

   6.5  Forming phosphoric-ester bonds

   6.6  Forming nitrogen-metal bonds

   6.7  Forming nitrogen-nitrogen bonds

 7. Translocases