Peroxo and oxo intermediates in mononuclear nonheme iron enzymes and related active sites

Fe-III-OOH and Fe-IV=O intermediates have now been documented in a number of nonheme iron active sites. In this Current Opinion we use spectroscopy combined with electronic structure calculations to define the frontier molecular orbitals (FMOs) of these species and their contributions to reactivity. For the low-spin Fe-III-OOH species in activated bleomycin we show that the reactivity of this nonheme iron intermediate is very different from that of the analogous Compound 0 of cytochrome P450. For Fe-IV=O S = 1 model species we experimentally define the electronic structure and its contribution to reactivity, and computationally evaluate how this would change for the Fe-IV=O S = 2 intermediates found in nonheme iron enzymes.