|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Most BioCyc compounds have been protonated to a reference pH value of 7.3, and some reactions have been computationally balanced for hydrogen by adding free protons. 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 synθse (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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