Sunday, October 18, 2009

37 - Biochemical reactions of Folate coenzymes

Coenzyme Form of Folate Involved and Single Carbon unit transferred
Formate activation
THF; -CHO group transferred.
Generation of 10-formyl-THF
Purine synthesis

Formation of glycinamide ribonucleotide
5,10-MethyleneTHF; -CHO group transferred
Formation of purines needed
for DNA, RNA synthesis, but reactions 
probably not rate limiting
Formylation of aminoimidazolecarboxamide-ribonucleotide (AICAR)
10-Formyl (CHO)THF;-CHO group transferred
Pyrimidine synthesis

Methylation of deoxyuridine monophosphate (dUMP) to thymidine monophosphate (dTMP)
5,10-MethyleneTHF;-CH3 group transferred.
Rate limiting in DNA synthesis
Oxidizes THF to DHF
Some breakdown
of folate at the C-9–N-10 bond
Amino acid interconversion

Serine–glycine interconversion
THF; =CH2 group transferred
Entry of single carbon units into active pool
Homocysteine to methionine
5-Methyl(M)THF; -CH3 group transferred
Demethylation of 5-MTHF to THF; also requires cobalamin, flavine adenine dinucleotide, ATP, and adenosyl
Forminoglutamic acid to glutamic acid in histidine catabolism
THF; -HN-CH= group transferred

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