1. Oxidoreductases

 2. Transferases

 3. Hydrolases

 4. Lyases

   4.1  Carbon-carbon lyases

   4.2  Carbon-oxygen lyases

   4.3  Carbon-nitrogen lyases

   4.4  Carbon-sulfur lyases

   4.5  Carbon-halide lyases

   4.6  Phosphorus-oxygen lyases

     4.6.1  Phosphorus-oxygen lyases (only sub-subclass identified to date)

       4.6.1.1  adenylate cyclase

       4.6.1.2  guanylate cyclase

       4.6.1.6  cytidylate cyclase

       4.6.1.12  2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase

       4.6.1.13  phosphatidylinositol diacylglycerol-lyase

       4.6.1.14  glycosylphosphatidylinositol diacylglycerol-lyase

       4.6.1.15  FAD-AMP lyase (cyclizing)

       4.6.1.16  tRNA-intron lyase

       4.6.1.17  cyclic pyranopterin monophosphate synthase

       4.6.1.18  pancreatic ribonuclease

       4.6.1.19  ribonuclease T2

       4.6.1.20  ribonuclease U2

       4.6.1.21  Enterobacter ribonuclease

       4.6.1.22  Bacillus subtilis ribonuclease

       4.6.1.23  ribotoxin

       4.6.1.24  ribonuclease T1

       4.6.1.25  bacteriophage T4 restriction endoribonuclease RegB

       4.6.1.26  uridylate cyclase

   4.7  carbon-phosphorus lyases

   4.8  Nitrogen-oxygen lyases

   4.98  ATP-independent chelatases

   4.99  Other lyases

 5. Isomerases

 6. Ligases

 7. Translocases