5,10-CH2-THF is synthesized from tetrahydrofolate (THF) through a series of enzymatic reactions. The enzyme methylenetetrahydrofolate reductase (MTHFR) catalyzes the transfer of a methylene group from 5,10-methenyltetrahydrofolate (5,10-CH=THF) to THF, forming 5,10-CH2-THF. Metabolic Functions...