KEGG Orthology (KO) [BR:req00001] 09100 Metabolism 09108 Metabolism of cofactors and vitamins 00790 Folate biosynthesis [PATH:req00790] REQ_05850 GTP cyclohydrolase I K01495 GCH1; GTP cyclohydrolase IA [EC:3.5.4.16] Enzymes [BR:req01000] 3. Hydrolases 3.5 Acting on carbon-nitrogen bonds, other than peptide bonds 3.5.4 In cyclic amidines 3.5.4.16 GTP cyclohydrolase I REQ_05850 GTP cyclohydrolase I K01495 GCH1; GTP cyclohydrolase IA [EC:3.5.4.16]