1. Oxidoreductases

 2. Transferases

   2.1  Transferring one-carbon groups

     2.1.1  Methyltransferases

     2.1.2  Hydroxymethyl-, formyl- and related transferases

       2.1.2.1  glycine hydroxymethyltransferase

       2.1.2.2  phosphoribosylglycinamide formyltransferase 1

       2.1.2.3  phosphoribosylaminoimidazolecarboxamide formyltransferase

       2.1.2.4  glycine formimidoyltransferase

       2.1.2.5  glutamate formimidoyltransferase

       2.1.2.7  D-alanine 2-hydroxymethyltransferase

       2.1.2.8  deoxycytidylate 5-hydroxymethyltransferase

       2.1.2.9  methionyl-tRNA formyltransferase

       2.1.2.10  aminomethyltransferase

       2.1.2.11  3-methyl-2-oxobutanoate hydroxymethyltransferase

       2.1.2.13  UDP-4-amino-4-deoxy-L-arabinose formyltransferase

       2.1.2.14  GDP-perosamine N-formyltransferase

     2.1.3  Carboxy- and carbamoyltransferases

     2.1.4  Amidinotransferases

     2.1.5  Methylenetransferases

   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

   2.8  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

   6.1  Forming carbon-oxygen bonds

   6.2  Forming carbon-sulfur bonds

   6.3  Forming carbon-nitrogen bonds

     6.3.1  Acid-D-ammonia (or amine) ligases (amide synthases)

     6.3.2  Acid-D-amino-acid ligases (peptide synthases)

     6.3.3  Cyclo-ligases

       6.3.3.1  phosphoribosylformylglycinamidine cyclo-ligase

       6.3.3.2  5-formyltetrahydrofolate cyclo-ligase

       6.3.3.3  dethiobiotin synthase

       6.3.3.4  (carboxyethyl)arginine beta-lactam-synthase

       6.3.3.5  O-ureido-D-serine cyclo-ligase

       6.3.3.6  carbapenam-3-carboxylate synthase

       6.3.3.7  Ni-sirohydrochlorin a,c-diamide reductive cyclase

     6.3.4  Other carbon-nitrogen ligases

     6.3.5  Carbon-nitrogen ligases with glutamine as amido-N-donor

   6.4  Forming carbon-carbon bonds

   6.5  Forming phosphoric-ester bonds

   6.6  Forming nitrogen-metal bonds

   6.7  Forming nitrogen-nitrogen bonds

 7. Translocases