5,10-Methenyltetrahydrofolate (5,10-CH=THF) is a form of tetrahydrofolate that is an intermediate in metabolism

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

. 5,10-CH=THF is a coenzyme that accepts and donates methenyl (CH=) groups.

It is produced from 5,10-methylenetetrahydrofolate

5,10-Methylenetetrahydrofolate

5,10-Methylenetetrahydrofolate is the substrate used by the enzyme methylenetetrahydrofolate reductase to generate 5-methyltetrahydrofolate ....

 by either a NAD+ dependent methylenetetrahydrofolate dehydrogenase

Methylenetetrahydrofolate dehydrogenase (NAD+)

In enzymology, a methylenetetrahydrofolate dehydrogenase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are 5,10-methylenetetrahydrofolate and NAD+, whereas its 3 products are 5,10-methenyltetrahydrofolate, NADH, and H+.This enzyme belongs to the family...

, or a NADP+ dependent dehydrogense

Methylenetetrahydrofolate dehydrogenase (NADP+)

In enzymology, a methylenetetrahydrofolate dehydrogenase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are 5,10-methylenetetrahydrofolate and NADP+, whereas its 3 products are 5,10-methenyltetrahydrofolate, NADPH, and H+.This enzyme belongs to the family...

. It can also be produced as an intermediate in histidine

Histidine

Histidine Histidine, an essential amino acid, has a positively charged imidazole functional group. It is one of the 22 proteinogenic amino acids. Its codons are CAU and CAC. Histidine was first isolated by German physician Albrecht Kossel in 1896. Histidine is an essential amino acid in humans...

 catabolism, by formiminotransferase cyclodeaminase

Formiminotransferase cyclodeaminase

Formiminotransferase cyclodeaminase is an enzyme that catalyzes the conversion of formiminoglutamate and tetrahydrofolate into formiminotetrahydrofolate and glutamate....

, from 5-formiminotetrahydrofolate

5-Formiminotetrahydrofolate

5-Formiminotetrahydrofolate is an intermediate in the catabolism of histidine. It is produced by glutamate formimidoyltransferase and then converted into 5,10-methenyltetrahydrofolate by formiminotransferase cyclodeaminase....

.

5,10-CH=THF is a substrate for methenyltetrahydrofolate cyclohydrolase

Methenyltetrahydrofolate cyclohydrolase

In enzymology, a methenyltetrahydrofolate cyclohydrolase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are 5,10-methenyltetrahydrofolate and H2O, whereas its product is 10-formyltetrahydrofolate....

, which converts it into 10-formyltetrahydrofolate.