Tetrahydrofolic acid

 ( Folates ) 

Tetrahydrofolic acid ( THFA), or tetrahydrofolate, is a folic acid derivative.

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Metabolism In humans, tetrahydrofolic acid is produced from dihydrofolic acid by dihydrofolate reductase. This reaction is inhibited by methotrexate. It is converted into 5,10-methylenetetrahydrofolate by serine hydroxymethyltransferase.

Many bacteria produce tetrahydrofolic acid via dihydropteroate. Humans lack the enzymes to do this, thus molecules that shut down these enzymes are effective antibacterial compounds. For example, sulfonamide antibiotics competitively binds the active site of dihydropteroate synthetase, excluding the binding of the dihydropteroate precuror, 4-aminobenzoic acid (PABA).

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Functions Tetrahydrofolic acid is a cofactor in many reactions, especially in the synthesis (or anabolism) of and . In addition, it serves as a carrier molecule for single-carbon moieties, that is, groups containing one carbon atom e.g. Methyl group, Methylene group, methenyl, Aldehyde, or formimino. When combined with one such single-carbon moiety as in 10-formyltetrahydrofolate, it acts as a donor of a group with one carbon atom. Tetrahydrofolate gets this extra carbon atom by sequestering formaldehyde produced in other processes. These single-carbon moieties are important in the formation of precursors for DNA synthesis. A shortage in tetrahydrofolic acid (FH4) can cause megaloblastic anemia.

Methotrexate acts on dihydrofolate reductase, like pyrimethamine or trimethoprim, as an inhibitor and thus reduces the amount of tetrahydrofolate made. This may result in megaloblastic anemia.

Tetrahydrofolic acid is involved in the conversion of formiminoglutamic acid to glutamic acid; this may reduce the amount of histidine available for decarboxylation and protein synthesis, and hence the urinary histamine and formiminoglutamic acid may be decreased.

Image:Dihydrofolic acid.svg|Dihydrofolic acid
Image:5,10-methylenetetrahydrofolic acid.svg|5,10-Methylenetetrahydrofolic acid
Image:10-formyl-tetrahydrofolic acid.svg|10-Formyltetrahydrofolic acid
     

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External links

• Tetrahydrofolate bound to proteins in the PDB

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