Important role of proton in activation of oxygen molecules in heme-containing oxygenases

DFT (density functional theory) calculations have revealed that the position of the proton of the hydroperoxide adduct of an Fe(III)–porphyrin compound influences greatly the electron density of the oxygen atoms of the peroxide ion, suggesting that the position of the proton in the hydroperoxo–iron(III) compound plays an important role in controlling the electronic interaction between the hydroperoxide adduct and the porphyrin system (OOH–π interaction).