How Heme Metabolism Occurs in Heme Oxygenase: Computational Study of Oxygen-Donation Ability of the Oxo and Hydroperoxo Species

We report a density functional theory study on the heme metabolism in heme oxygenase using iron?hydroperoxo and ?oxo models. The activation energies for heme oxidation at the α-carbon by the iron?hydroperoxo and ?oxo species are calculated to be 42.9 and 39.9 kcal/mol, respectively. These high activation barriers lead us to reconsider the catalytic mechanism of heme oxygenase.