The catalytic pathway of cytochrome P450cam at atomic resolution

Members of the cytochrome P450 superfamily catalyze the addition of molecul ar oxygen to nonactivated hydrocarbons at physiological temperature-a react ion that requires high temperature to proceed in the absence of a catalyst. Structures were obtained for three intermediates in the hydroxylation reac tion of camphor by P450cam with trapping techniques and cryocrystallography . The structure of the ferrous dioxygen adduct of P450cam was determined wi th 0.91 angstrom wavelength x-rays; irradiation with 1.5 angstrom x-rays re sults in breakdown of the dioxygen molecule to an intermediate that would b e consistent with an oxyferryl species. The structures show conformational changes in several important residues and reveal a network of bound water m olecules that may provide the protons needed for the reaction.