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 alpha-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