5,10-Methylenetetrahydrofolate (MTHF)

5,10-Methylenetetrahydrofolate (5,10-CH2-THF, MTHF) is the substrate used by methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate (5-MTHF). 5,10-CH2-THF is also a coenzyme used in thymidine biosynthesis by thymidylate synthase (FAD).
5-Methyltetrahydrofolate (5-Me-THF, 5-Me-H4F), or 5-methyltetrahydrofolic acid (5-Me-THFA, 5-Me-H4FA) the predominant metabolic form of folate, is a methylated derivate of tetrahydrofolate (THF, H4F). It is generated by methylenetetrahydrofolate reductase (MTHFR) from 5,10-methylenetetrahydrofolate (5,10-CH2-THF, MTHF) and used to recycle homocysteine back to methionine by 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) or methionine synthase (MS).