Methenyltetrahydrofolate cyclohydrolase

In enzymology, a methenyltetrahydrofolate cyclohydrolase (EC 3.5.4.9) is an enzyme that catalyzes the chemical reaction

methenyltetrahydrofolate cyclohydrolase
Methenyltetrahydrofolate cyclohydrolase dimer, Human
Identifiers
EC no.	3.5.4.9
CAS no.	9027-97-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

5,10-methenyltetrahydrofolate + H₂O ${\displaystyle \rightleftharpoons }$ 10-formyltetrahydrofolate

Thus, the two substrates of this enzyme are 5,10-methenyltetrahydrofolate and H₂O, whereas its product is 10-formyltetrahydrofolate.

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amidines.

This enzyme participates in glyoxylate and dicarboxylate metabolism and one carbon pool by folate.

Synonyms

The systematic name of this enzyme class is 5,10-methenyltetrahydrofolate 5-hydrolase (decyclizing).

Other names in common use include:

• Citrovorum factor cyclodehydrase
• cyclohydrolase
• formyl-methenyl-methylenetetrahydrofolate synthetase (combined).

Structural studies

As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1A4I, 1DIA, 1DIB, 1DIG, 2C2X, and 2C2Y.

References

• Rabinowitz JC, Pricer WE (1956). "The enzymatic synthesis of N10-formyltetrahydrofolic acid and its role in ATP formation during formiminoglycine degradation". J. Am. Chem. Soc. 78 (16): 4176–4178. doi:10.1021/ja01597a094.
• Tabor H, Wyngarden L (July 1959). "The enzymatic formation of formiminotetrahydrofolic acid, 5,10-methenyltetrahydrofolic acid, and 10-formyltetrahydrofolic acid in the metabolism of formiminoglutamic acid". The Journal of Biological Chemistry. 234 (7): 1830–46. PMID 13672973.