157 11.11 Folate Functions
The major function of folate is that it participates in 1-carbon metabolism. As described earlier, this is the transfer of 1-carbon units from 1 compound to another. The cofactor form of folate is tetrahydrofolate (THF). As is shown in the figure below, in order for THF to be formed, a methyl group is transferred to cobalamin (vitamin B12) from 5-methyl THF (THF plus a methyl group), forming methyl-cobalamin. You can see this on the left side of the figure below.
There are 2 major cofactor functions of THF1:
1. DNA Synthesis
THF is required for the synthesis of DNA bases (purines and pyrimidines)1. As shown in the link below, N10-formyl-THF (a form of THF) is needed in 2 reactions (3 and 9) in purine synthesis.
| Web Link |
2. Amino Acid Metabolism
THF is a cofactor for enzymes that metabolize histidine, serine, glycine, and methionine1. The following link shows that THF is a cofactor for serine hydroxymethyltransferase, the enzyme that converts serine to glycine.
| Web Link |
References & Links
1. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
Links
Purine Synthesis – http://themedicalbiochemistrypage.org/images/purinesynthesis.jpg
Serine to Glycine – http://themedicalbiochemistrypage.org/images/glycine-synthesis.jpg