Formimidoyltransferase cyclodeaminase or formiminotransferase cyclodeaminase (gene symbol FTCD in humans) is a bifunctional enzyme that catalyzes the following reactions:^[1]

• conversion of formiminoglutamate and tetrahydrofolate into formiminotetrahydrofolate and glutamate (glutamate formimidoyltransferase activity, EC 2.1.2.5)
• subsequent deamination of formiminotetrahydrofolate to 5,10-methenyltetrahydrofolate and ammonia (formimidoyltetrahydrofolate cyclodeaminase activity, EC 4.3.1.4)

Its name comes from the two activities it catalyzes.

Mutations of the FTCD gene cause glutamate formiminotransferase deficiency.^[1]

• Glutamate-1-semialdehyde