Figure 3.
Reaction intermediates of MTHFS catalysis. The iminium phosphate (Intermediate 1) results from the transfer of the ATP γ-phosphate to 5-formylTHF; the phosphoimidazolidine (Intermediate 2) results from N10 nucleophilic attack to form a species with a tetrahedral carbon, which then breaks down rapidly to eliminate phosphate and form product, methenylTHF. pABG indicates p-aminobenzoylglutamate.