tetrahüdrofolaat

Tetrahydrofolate, often abbreviated as THF, is a vital coenzyme in biological systems. It is the reduced form of folic acid, also known as vitamin B9. THF plays a crucial role in one-carbon metabolism, acting as a carrier for various one-carbon units such as methyl (-CH3), methylene (-CH2-), and formyl (-CHO) groups. These one-carbon transfers are essential for numerous metabolic pathways.

The primary function of THF is in the synthesis of purines and pyrimidines, the building blocks of DNA and RNA. Without sufficient THF, DNA synthesis is impaired, which can lead to megaloblastic anemia, a condition characterized by enlarged red blood cells. Furthermore, THF is involved in the interconversion of amino acids, particularly in the metabolism of serine, glycine, and methionine. It is also implicated in the methylation of various molecules, including DNA and proteins, which are important for gene regulation and protein function.

THF is generated from dihydrofolate (DHF) by the enzyme dihydrofolate reductase (DHFR), a reaction that requires NADPH. DHF, in turn, is derived from dietary folic acid. The folate cycle, a complex series of reactions involving THF and its derivatives, is tightly regulated to ensure adequate supply of one-carbon units for cellular processes. Due to its critical role in cell division and growth, THF metabolism is a target for certain drugs, such as methotrexate, which inhibits DHFR and is used in chemotherapy and as an immunosuppressant.