GTP cyclohydrolase activity GTP cyclohydrolase I activity https://github.com/geneontology/go-ontology/issues/26710 https://github.com/geneontology/go-ontology/issues/30193 Reactome:R-HSA-1474146 guanosine triphosphate cyclohydrolase activity KEGG_REACTION:R00424 EC:3.5.4.16 RHEA:17473 GTP 8-formylhydrolase activity dihydroneopterin triphosphate synthase activity molecular_function GTP 7,8-8,9-dihydrolase activity GO:0003934 Catalysis of the reaction: GTP + H2O = 7,8-dihydroneopterin 3'-triphosphate + formate + H+. guanosine triphosphate 8-deformylase activity MetaCyc:GTP-CYCLOHYDRO-I-RXN