Reaction: GTP + H2O = 7,8-dihydroneopterin 2',3'-cyclic phosphate + formate + diphosphate
For diagram of reaction click here.
Glossary: 7,8-dihydroneopterin 2',3'-cyclic phosphate = 2-amino-6-{(S)-hydroxy[(4R)-2-hydroxy-2-oxido-1,3,2-dioxaphospholan-4-yl]methyl}-7,8-dihydropteridin-4(1H)-one = 2-amino-6-[(1S,2R)-1,2,3-trihydroxypropyl]-7,8-dihydro-4(1H)-pteridinone 1,2-cyclic phosphate
Other name(s): MptA; GTP cyclohydrolase MptA
Systematic name: GTP 7,8-8,9-dihydrolase (cyclizing, formate-releasing, diphosphate-releasing)
Comments: Requires Fe2+. A zinc protein. The enzyme is involved in methanopterin biosynthesis in methanogenic archaea. cf. GTP cyclohydrolase I (EC 3.5.4.16), GTP cyclohydrolase II (EC 3.5.4.25) and GTP cyclohydrolase IIa (EC 3.5.4.29).
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
References:
1. Grochowski, L.L., Xu, H., Leung, K. and White, R.H. Characterization of an Fe2+-dependent archaeal-specific GTP cyclohydrolase, MptA, from Methanocaldococcus jannaschii. Biochemistry 46 (2007) 6658-6667. [PMID: 17497938]