1. Oxidoreductases

   1.1  Acting on the CH-OH group of donors

   1.2  Acting on the aldehyde or oxo group of donors

   1.3  Acting on the CH-CH group of donors

   1.4  Acting on the CH-NH2 group of donors

   1.5  Acting on the CH-NH group of donors

   1.6  Acting on NADH or NADPH

   1.7  Acting on other nitrogenous compounds as donors

     1.7.1  With NAD+ or NADP+ as acceptor

     1.7.2  With a cytochrome as acceptor

     1.7.3  With oxygen as acceptor

     1.7.5  With a quinone or similar compound as acceptor

       1.7.5.1  nitrate reductase (quinone)

       1.7.5.2  nitric oxide reductase (menaquinol)

     1.7.6  With a nitrogenous group as acceptor

     1.7.7  With an iron-sulfur protein as acceptor

     1.7.99  With unknown physiological acceptors

   1.8  Acting on a sulfur group of donors

   1.9  Acting on a heme group of donors

   1.10  Acting on diphenols and related substances as donors

   1.11  Acting on a peroxide as acceptor

   1.12  Acting on hydrogen as donor

   1.13  Acting on single donors with incorporation of molecular oxygen (oxygenases)

   1.14  Acting on paired donors, with incorporation or reduction of molecular oxygen

   1.15  Acting on superoxide as acceptor

   1.16  Oxidizing metal ions

   1.17  Acting on CH or CH2 groups

   1.18  Acting on iron-sulfur proteins as donors

   1.19  Acting on reduced flavodoxin as donor

   1.20  Acting on phosphorus or arsenic in donors

   1.21  Catalysing the reaction X-H + Y-H = X-Y

   1.23  Reducing C-O-C group as acceptor

   1.97  Other oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

 5. Isomerases

 6. Ligases

 7. Translocases