EC Number   |
Reaction |
Reference |
|---|
    2.5.1.15 | (7,8-dihydropterin-6-yl)methyl diphosphate + 4-aminobenzoate = diphosphate + 7,8-dihydropteroate |
- |
- |
| 2.5.1.15 | (7,8-dihydropterin-6-yl)methyl diphosphate + 4-aminobenzoate = diphosphate + 7,8-dihydropteroate |
SN1 reaction mechanism via formation of a novel cationic pterin intermediate, quantum chemical modelling of the initial step, overview. Two conserved loops generate a substructure during catalysis that creates a specific binding pocket for 4-aminobenzoic acid, one of the two DHPS substrates. The carboxylate moiety of 4-aminobenzoic acid is accommodated by Ser221 and the helix dipole of helix alphaLoop7 |
723771 |
| 2.5.1.15 | (7,8-dihydropterin-6-yl)methyl diphosphate + 4-aminobenzoate = diphosphate + 7,8-dihydropteroate |
the reaction catalyzed by DHPS involves a nucleophilic attack by the amino nitrogen of 4-aminobenzoate on the exocyclic methyl carbon of DHPP. This results in the formation of the N-C bond and the elimination of the pyrophosphate moiety as a leaving group. A partial carbocation intermediate is believed to form at the extra-cyclic methylene in the transition state, which is stabilized by delocalization of the charge in the adjacent double bond of the pterin ring. Evidence supporting transient carbocation intermediate is shown by the inability of the oxidized form of DHPP (pterin-6-hydroxymethyl pyrophosphate) to act as a DHPS substrate |
721829 |
