1. Oxidoreductases

 2. Transferases

   2.1  Transferring one-carbon groups

   2.2  Transferring aldehyde or ketonic groups

   2.3  Acyltransferases

   2.4  Glycosyltransferases

   2.5  Transferring alkyl or aryl groups, other than methyl groups

   2.6  Transferring nitrogenous groups

   2.7  Transferring phosphorus-containing groups

     2.7.1  Phosphotransferases with an alcohol group as acceptor

     2.7.2  Phosphotransferases with a carboxy group as acceptor

     2.7.3  Phosphotransferases with a nitrogenous group as acceptor

     2.7.4  Phosphotransferases with a phosphate group as acceptor

     2.7.6  Diphosphotransferases

     2.7.7  Nucleotidyltransferases

     2.7.8  Transferases for other substituted phosphate groups

     2.7.9  Phosphotransferases with paired acceptors

     2.7.10  Protein-tyrosine kinases

     2.7.11  Protein-serine/threonine kinases

     2.7.12  Dual-specificity kinases (those acting on Ser/Thr and Tyr residues)

       2.7.12.1  dual-specificity kinase

       2.7.12.2  mitogen-activated protein kinase kinase

     2.7.13  Protein-histidine kinases

     2.7.14  Protein-arginine kinases

     2.7.99  Other protein kinases

   2.8  Transferring sulfur-containing groups

   2.9  Transferring selenium-containing groups

   2.10  Transferring molybdenum- or tungsten-containing groups

 3. Hydrolases

 4. Lyases

 5. Isomerases

 6. Ligases

 7. Translocases