5,10-Methylenetetrahydrofolate
![](/Images/godic/202501/27/5,10-methylenetetrahydrofolic_acid.svg0912.png")
![MTHFR metabolism: folate cycle, methionine cycle, trans-sulfuration and hyperhomocysteinemia. 5-MTHF: 5-methyltetrahydrofolate; 5,10-methyltetrahydrofolate; BAX: Bcl-2-associated X protein; BHMT: betaine-homocysteine S-methyltransferase; CBS: cystathionine beta synthase; CGL: cystathionine gamma-lyase; DHF: dihydrofolate (vitamin B9); DMG: dimethylglycine; dTMP: thymidine monophosphate; dUMP: deoxyuridine monophosphate; FAD+ flavine adenine dicucleotide; FTHF: 10-formyltetrahydrofolate; MS: methionine synthase; MTHFR: mehtylenetetrahydrofolate reductase; SAH: S-adenosyl-L-homocysteine; SAME: S-adenosyl-L-methionine; THF: tetrahydrofolate.](/Images/godic/202501/27/MTHFR_metabolism.svg0913.png")
5,10-Methylenetetrahydrofolate (5,10-CH2-THF) is the substrate used by the enzyme methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate (5-MTHF, or levomefolic acid).
5,10-CH2-THF can also be used as a coenzyme in the biosynthesis of thymidine. To be specific, it is the C1-donor in the reactions catalyzed by thymidylate synthase and thymidylate synthase (FAD). It also acts as a cofactor in the synthesis of serine from glycine via the enzyme serine hydroxymethyl transferase.