Figure 10.

Electrostatic potential surfaces of PviPRX9 and phenylpropanoids. A, Heme (hexcoordinate, high spin), Arg-31 (as methylguanidinium), Ser-35 (as ethanol), Arg-38 (as n-propylguanidinium), Phe-41 (as toluene), His-42 (as 5-methyl-1H-imidazole; mostly obscured by Leu-66), Ala-65 (as ACE) to Arg-73 (as NMA), Gly-170 (as formamide), Asp-135 (as ACE) to Phe-141 (as NMA), Ala-172 (as ACE) to Phe-177 (as NMA), His-167 (as 5-methyl-1H-imidazole), Asp-326 (as acetate ion), and six water molecules; Cys-174 was mutated to Gly to reduce computational cost. ACE and NMA are acetyl and N-methyl capping groups on the N and C termini, respectively, of each stretch of multiple residues. The three water molecules circled with dashed lines were, from right to left, the water involved in the first proton transfer, a noncatalytic water that occupies the nascent binding site of the hydroxycinnamyl substrate phenol functional group, and the water released upon H₂O₂ binding to the heme. The latter water molecule was regenerated by heterolytic cleavage of H₂O₂ and involved in catalytic proton transfer. B, p-Coumaryl aldehyde. C, Caffeyl aldehyde. D, Coniferyl aldehyde. E, Sinapyl aldehyde. F, p-Coumarate. G, Caffeate. H, Ferulate. I, Sinapate. J, p-Coumaryl alcohol. K, Caffeyl alcohol. L, Coniferoyl alcohol. M, Sinapyl alcohol. The active site and ligand electrostatic potentials, mapped on their corresponding self-consistent field densities, are shown on a potential scale of −2.7 × 10⁻¹ hartrees (red) to +2.97 × 10¹ hartrees (blue) for the active site and −1 × 10⁻¹ (red) to 3 × 10¹ (blue) for the ligands. This figure was generated using GaussView 3.09.