Carnegie Mellon University Department of Chemistry

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Münck Group paper in Science and lead story in News of the Week segment of Chemical & Engineering News

photo of Audria Stubna and Eckard Munck.A large group of iron-containing enzymes catalyze processes that involve the activation of dioxygen. Products of catalysis include fatty acids, steroids, DNA, dopa, and penicillin, to name a few. Proposed catalytic cycles invariably postulate an Fe(IV)-oxo intermediate. However, no evidence of such a species in a non-heme environment has been reported. While many biochemical groups are hard at work to trap such intermediates, Eckard Münck and graduate student Audria Stubna, in collaboration with the Que group at the University of Minnesota, are pursuing the subject by preparing synthetic complexes at cryogenic temperatures for Mössbauer, EXAFS and Resonance Raman studies. During the past year the two groups have studied a number of novel Fe(IV)=O complexes, and a recently prepared reactive intermediate is so stable at -40° C that it could be crystallized. The Science paper describes the first high-resolution structure of an Fe(IV)=O complex. The reported work demonstrates Fe(IV)-oxo moleculethat protein environments should be able to support “hot” Fe(IV) intermediates. The C & E News article by Amanda Yarnell has the headline “Ironing Out O2 Activation”. While much work needs to be done, the Science paper reports substantial progress in that ironing-out endeavor.

February 2003