1. Oxidoreductases

 2. Transferases

 3. Hydrolases

   3.1  Acting on ester bonds

     3.1.1  Carboxylic-ester hydrolases

     3.1.2  Thioester hydrolases

     3.1.3  Phosphoric-monoester hydrolases

     3.1.4  Phosphoric-diester hydrolases

     3.1.5  Triphosphoric-monoester hydrolases

     3.1.6  Sulfuric-ester hydrolases

     3.1.7  Diphosphoric-monoester hydrolases

     3.1.8  Phosphoric-triester hydrolases

     3.1.11  Exodeoxyribonucleases producing 5'-phosphomonoesters

     3.1.12  Exodeoxyribonucleases producing 3'-phosphomonoesters

     3.1.13  Exoribonucleases producing 5'-phosphomonoesters

       3.1.13.1  exoribonuclease II

       3.1.13.2  exoribonuclease H

       3.1.13.3  oligonucleotidase

       3.1.13.4  poly(A)-specific ribonuclease

       3.1.13.5  ribonuclease D

     3.1.14  Exoribonucleases producing 3'-phosphomonoesters

     3.1.15  Exonucleases that are active with either ribo- or deoxyribonucleic acids and produce 5'-phosphomonoesters

     3.1.16  Exonucleases that are active with either ribo- or deoxyribonucleic acids and produce 3'-phosphomonoesters

     3.1.21  Endodeoxyribonucleases producing 5'-phosphomonoesters

     3.1.22  Endodeoxyribonucleases producing 3'-phosphomonoesters

     3.1.25  Site-specific endodeoxyribonucleases that are specific for altered bases

     3.1.26  Endoribonucleases producing 5'-phosphomonoesters

     3.1.27  Endoribonucleases producing 3'-phosphomonoesters

     3.1.30  Endoribonucleases that are active with either ribo- or deoxyribonucleic acids and produce 5'-phosphomonoesters

     3.1.31  Endoribonucleases that are active with either ribo- or deoxyribonucleic acids and produce 3'-phosphomonoesters

   3.2  Glycosylases

   3.3  Acting on ether bonds

   3.4  Acting on peptide bonds (peptidases)

   3.5  Acting on carbon-nitrogen bonds, other than peptide bonds

   3.6  Acting on acid anhydrides

   3.7  Acting on carbon-carbon bonds

   3.8  Acting on halide bonds

   3.9  Acting on phosphorus-nitrogen bonds

   3.10  Acting on sulfur-nitrogen bonds

   3.11  Acting on carbon-phosphorus bonds

   3.12  Acting on sulfur-sulfur bonds

   3.13  Acting on carbon-sulfur bonds

 4. Lyases

 5. Isomerases

 6. Ligases

 7. Translocases