Furthermore, the specific orientation of glutamate and histidine residues at positions 112 and 121 led us to hypothesize that these residues play a crucial role in the formation and stabilization of the high-valent intermediate, compound I, Figure . Drawing inspiration from the Poulos-Kraut mechanism, we hypothesized a plausible mechanism to explain how these intermediates contribute to the observed reactivity by stabilizing compound I, Figure . Given the reaction conditions (pH 6), the histidine residue at position 121 is expected to be K121H provided additional evidence suggesting that electron transfer during this oxidation process likely occurs through an outer-sphere mechanism. This conclusion is supported by the fact that there is sufficient space for one imidazole ligand to bind, which is inadequate to accommodate substrates such as TMB or ABTS.