EC Explorer

4.1.99.22

GTP 3′,8-cyclase

GTP + S-adenosyl-L-methionine + reduced electron acceptor = (8S)-3′,8-cyclo-7,8-dihydroguanosine 5′-triphosphate + 5′-deoxyadenosine + L-methionine + oxidized electron acceptor

MOCS1A (gene name), moaA (gene name), cnx2 (gene name)

GTP 3′,8-cyclase [(8S)-3′,8-cyclo-7,8-dihydroguanosine 5′-triphosphate-forming]

The enzyme catalyses an early step in the biosynthesis of the molybdenum cofactor (MoCo). In bacteria and plants the reaction is catalysed by MoaA and Cnx2, respectively. In mammals it is catalysed by the MOCS1A domain of the bifunctional MOCS1 protein, which also catalyses EC 4.6.1.17, cyclic pyranopterin monophosphate synthase. The enzyme belongs to the superfamily of radical S-adenosyl-L-methionine (radical SAM) enzymes, and contains two oxygen-sensitive FeS clusters.

created 2011 as EC 4.1.99.18, part transferred 2016 to EC 4.1.99.22