Tetrahydrofolic acid is a folic acid derivative.
Metabolism
Human synthesis
It is produced from dihydrofolic acid by dihydrofolate reductase. This reaction is inhibited by trimethoprim.
It is converted into 5,10-methylenetetrahydrofolate by serine hydroxymethyltransferase.
Bacterial synthesis
Many bacteria use dihydropteroate synthetase to produce dihydropteroate in bacteria, an enzyme without function in humans. This makes it a useful target for sulfonamide antibiotics, which compete with the PABA precursor.
Functions
It is a coenzyme in many reactions, especially in the metabolism of amino acids and nucleic acids. It acts as a donor of a group with one carbon atom. It gets this carbon atom by sequestering formaldehyde produced in other processes. A shortage in THF can cause anemia.
Tetrahydrofolic acid is reduced by the drug methotrexate, which is used to impair nucleotide synthesis. This drug is a potent chemotherapy and anti rheumatic.
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