|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 18.104.22.168
The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the Enzyme Commission system.
Most BioCyc compounds have been protonated to a reference pH value of 7.3. Please see the PGDB Concepts Guide for more information.
Mass balance status: Balanced.
Enzyme Commission Primary Name: methenyltetrahydrofolate cyclohydrolase
Enzyme Commission Synonyms: Citrovorum factor cyclodehydrase, cyclohydrolase, formyl-methenyl-methylenetetrahydrofolate synthetase (combined)
Standard Gibbs Free Energy (ΔrG'° in kcal/mol): -5.2422333 [Latendresse13]
Enzyme Commission Summary:
In eukaryotes, the enzyme occurs as a trifunctional enzyme that also has methylenetetrahydrofolate dehydrogenase (NADP+) ( EC 22.214.171.124) and formatetetrahydrofolate ligase ( EC 126.96.36.199) activity. In some prokaryotes, it occurs as a bifunctional enzyme that also has dehydrogenase ( EC 188.8.131.52) activity or formimidoyltetrahydrofolate cyclodeaminase ( EC 184.108.40.206) activity.
This reaction is involved in folic acid synthesis and is necessary for the biosynthesis of purines, thymydylate, methionine, histidine, pantothenate and formyl tRNA-MET.
Tabor59: Tabor, H., Wyngarden, L. (1959). "The enzymatic formation of formiminotetrahydrofolic acid, 5,10-methenyltetrahydrofolic acid, and 10-formyltetrahydrofolic acid in the metabolism of formiminoglutamic acid." J Biol Chem 234(7);1830-46. PMID: 13672973
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