Reaction: 5-formimidoyltetrahydrofolate = 5,10-methenyltetrahydrofolate + NH3
For diagram of reaction click here (another example).
Other name(s): formiminotetrahydrofolate cyclodeaminase; 5-formimidoyltetrahydrofolate ammonia-lyase (cyclizing)
Systematic name: 5-formimidoyltetrahydrofolate ammonia-lyase (cyclizing; 5,10-methenyltetrahydrofolate-forming)
Comments: In eukaroytes, occurs as a bifunctional enzyme that also has glutamate formimidoyltransferase (EC 2.1.2.5) activity.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9032-05-7
References:
1. Rabinowitz, J.C. and Pricer, W.E. Formimino-tetrahydrofolic acid and methenyltetrahydrofolic acid as intermediates in the formation of N10-formyltetrahydrofolic acid. J. Am. Chem. Soc. 78 (1956) 5702-5704.