Chemistry:Tetrahydrofolic acid

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Tetrahydrofolic acid
Skeletal formula of tetrahydrofolic acid
Space-filling model of the tetrahydrofolic acid molecule
Names
IUPAC name
N-[4-({[(6Ξ)-2-Amino-4-oxo-1,4,5,6,7,8-hexahydropteridin-6-yl]methyl}amino)benzoyl]-L-glutamic acid
Systematic IUPAC name
(2S)-2-[4-({[(6Ξ)-2-Amino-4-oxo-1,4,5,6,7,8-hexahydropteridin-6-yl]methyl}amino)benzamido]pentanedioic acid
Identifiers
3D model (JSmol)
3DMet
101189
ChEBI
ChemSpider
DrugBank
KEGG
MeSH 5,6,7,8-tetrahydrofolic+acid
UNII
Properties
C
19
H
23
N
7
O
6
Molar mass 445.43 g/mol
Melting point 250 °C (482 °F; 523 K)
0.27 g/L
Acidity (pKa) 3.51
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Tetrahydrofolic acid (THFA), or tetrahydrofolate, is a folic acid derivative.

Metabolism

File:Pathway of tetrahydrofolate and antimetabolites.pdf
Pathway of tetrahydrofolate and antimetabolites

In humans, tetrahydrofolic acid is produced from dihydrofolic acid by dihydrofolate reductase. This reaction is inhibited by methotrexate.[1] It is converted into 5,10-methylenetetrahydrofolate by serine hydroxymethyltransferase.

Many bacteria produce tetrahydrofolic acid via dihydropteroate.[citation needed] 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 precursor, 4-aminobenzoic acid (PABA).

Functions

Tetrahydrofolic acid is a cofactor in many reactions, especially in the synthesis (or anabolism) of amino acids and nucleic acids. In addition, it serves as a carrier molecule for single-carbon moieties, that is, groups containing one carbon atom e.g. methyl, methylene, methenyl, formyl, 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.[2][3][4]

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.[5]

References

  1. Rajagopalan, P. T. Ravi; Zhang, Zhiquan; McCourt, Lynn; Dwyer, Mary; Benkovic, Stephen J.; Hammes, Gordon G. (2002-10-15). "Interaction of dihydrofolate reductase with methotrexate: Ensemble and single-molecule kinetics" (in en). Proceedings of the National Academy of Sciences 99 (21): 13481–13486. doi:10.1073/pnas.172501499. ISSN 0027-8424. PMID 12359872. Bibcode2002PNAS...9913481R. 
  2. "Biochemistry: The One-Carbon Pool: Folate and B12 Metabolism". 2008-02-23. https://liveonearth.livejournal.com/260487.html. 
  3. Yadav, Manish K.; Manoli, Nandini M.; Madhunapantula, SubbaRao V. (2016-10-25). Roemer, Klaus. ed. "Comparative Assessment of Vitamin-B12, Folic Acid and Homocysteine Levels in Relation to p53 Expression in Megaloblastic Anemia" (in en). PLOS ONE 11 (10). doi:10.1371/journal.pone.0164559. ISSN 1932-6203. PMID 27780269. Bibcode2016PLoSO..1164559Y. 
  4. Aslinia, F.; Mazza, J. J.; Yale, S. H. (2006-09-01). "Megaloblastic Anemia and Other Causes of Macrocytosis" (in en). Clinical Medicine & Research 4 (3): 236–241. doi:10.3121/cmr.4.3.236. ISSN 1539-4182. PMID 16988104. 
  5. "Histamine formation in guinea-pigs". J. Physiol. 181 (4): 801–9. December 1965. doi:10.1113/jphysiol.1965.sp007798. PMID 5881255.