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Wednesday, April 09, 2014

Nickel Superoxide Dismutase: From Models to Enzymes

Inorganic Inorganic Seminar
1640 Chemistry
4:00 PM - 5:30 PM

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Contact:   lehnertn@umich.edu

Speaker:   Jason Shearer, University of Nevada
Abstract:   Nickel containing superoxide dismutase (NiSOD) is a mononuclear thiolate ligated nickel metalloenzyme that catalyzes the disproportionation of superoxide. Despite being the most recently discovered SOD, NiSOD is the most widely expressed superoxide degradation enzyme found in the aquatic genome. This talk will focus on our efforts towards understanding the structure of the NiSOD active site and the catalytic mechanism by-which NiSOD facilitates superoxide disproportionation. Attention will be devoted to metallopeptide based NiSOD mimics, which reproduce the structure, spectroscopic and functional properties of the metalloenzyme. We will provide evidence that these mimics disproportionate superoxide via a proton-coupled electron-transfer reaction with the “hydrogen atom” originating from a protonated reduced Ni(II)-S(H+)-Cys moiety. It will be shown that both NiSOD and metallopeptide based mimics of NiSOD operate through outersphere mechanisms, but the fine mechanistic details of the two systems are distinct.