510metylentetrahydrofolat

5,10-methylene tetrahydrofolate, also written as 5,10-CH2-THF, is a reduced form of tetrahydrofolate (THF) that serves as a carrier of single-carbon units in one-carbon metabolism. It is one of several folate cofactors involved in nucleotide synthesis and amino acid metabolism, and is sometimes referred to by names such as 5,10-methylenetetrahydrofolate or 5,10-CH2-THF.

Biochemically, 5,10-CH2-THF is produced from THF by serine hydroxymethyltransferase, which transfers a methylene group from serine. It is a key substrate in the synthesis of deoxythymidine monophosphate (dTMP) via thymidylate synthase, contributing to DNA synthesis by converting dUMP to dTMP and generating dihydrofolate, which is recycled back to THF by dihydrofolate reductase. It can also be reduced by methylenetetrahydrofolate reductase (MTHFR) to 5-methyl-THF, the principal circulating form of folate used to remethylate homocysteine to methionine in collaboration with vitamin B12 and methionine synthase.

Physiological significance and clinical relevance arise from its roles in DNA synthesis and methylation reactions. Adequate folate levels support normal cell division and development; deficiency can lead to anemia and elevated homocysteine, while antifolate drugs such as methotrexate disrupt THF cycling to treat certain cancers and autoimmune conditions. Variants in enzymes regulating the folate cycle, including MTHFR, can influence folate metabolism and disease risk.