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.