Hydrolases;
Acting on carbon-nitrogen bonds, other than peptide bonds;
In cyclic amidines
BRITE hierarchy

5,10-methenyltetrahydrofolate 5-hydrolase (ring-opening)

5,10-methenyltetrahydrofolate + H2O = 10-formyltetrahydrofolate [RN:R01655]

R01655
Reaction

5,10-methenyltetrahydrofolate [CPD:C00445];
H2O [CPD:C00001]

In eukaryotes, the enzyme occurs as a trifunctional enzyme that also has methylenetetrahydrofolate dehydrogenase (NADP+) (EC 1.5.1.5) and formate---tetrahydrofolate ligase (EC 6.3.4.3) activity. In some prokaryotes, it occurs as a bifunctional enzyme that also has dehydrogenase (EC 1.5.1.5) activity or formimidoyltetrahydrofolate cyclodeaminase (EC 4.3.1.4) activity.

EC 3.5.4.9 created 1961