A novel tripeptide model of nickel superoxide dismutase
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Issue Date
2010-01-18Article Version
Scholarly/refereed, author accepted manuscript
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Nickel superoxide dismutase (Ni-SOD) catalyzes the disproportionation of superoxide to molecular oxygen and hydrogen peroxide, but the overall reaction mechanism has yet to be determined. Peptide-based models of the 2N:2S nickel coordination sphere of Ni-SOD have provided some insight into the mechanism of this enzyme. Here we show that the coordination sphere of Ni-SOD can be mimicked using the tripeptide asparagine-cysteine-cysteine (NCC). NCC binds nickel with extremely high affinity at physiological pH with 2N:2S geometry, as demonstrated by electronic absorption and circular dichroism (CD) data. Like Ni-SOD, Ni-NCC has mixed amine/amide ligation that favors metal-based oxidation over ligand-based oxidation. Electronic absorption, CD, and magnetic CD data (MCD) collected for Ni-NCC are consistent with a diamagnetic Ni(II) center bound in square planar geometry. Ni-NCC is quasi-reversibly oxidized with a midpoint potential of 0.72(2) V (versus Ag/AgCl) and breaks down superoxide in an enzyme-based assay, supporting its potential use as a model for Ni-SOD chemistry.
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This document is the Accepted Manuscript version of a Published Work that appeared in final form in the Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/ic901828m.
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Krause, M. E., Glass, A. M., Jackson, T. A., & Laurence, J. S. (2010). A novel tripeptide model of nickel superoxide dismutase. Inorganic Chemistry, 49(2), 362–364. http://doi.org/10.1021/ic901828m.
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