Ambika Bhagi-Damodaran1, Matthew A. Michael2, Qianhong Zhu3, Julian Reed4,
Braddock A. Sandoval1, Evan N. Mirts5, Saumen Chakraborty1, Pierre Moënne-Loccoz3*,
Yong Zhang2* and Yi Lu1,4,5*
Nature Chemistry doi:10.1038/nchem.2643
Nature Chemistry doi:10.1038/nchem.2643
- Received
- Accepted
- Published online
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. 2 Department of Biomedical Engineering, Chemistry, and
Biological Sciences, Stevens Institute of Technology, Hoboken, New Jersey, USA. 3 Division of Environmental & Biomolecular Systems, Institute of
Environmental Health, Oregon Health & Science University
4 Department of Biochemistry,
University of Illinois at Urbana-Champaign
5 Center for Biophysics and Quantitative Biology, University of Illinois at
Urbana-Champaign, Urbana, Illinois, USA.
Abstract
Abstract
Haem–copper oxidase (HCO) catalyses the natural reduction of oxygen to water using a haem-copper centre. Despite
decades of research on HCOs, the role of non-haem metal and the reason for nature’s choice of copper over other metals
such as iron remains unclear. Here, we use a biosynthetic model of HCO in myoglobin that selectively binds different
non-haem metals to demonstrate 30-fold and 11-fold enhancements in the oxidase activity of Cu- and Fe-bound HCO
mimics, respectively, as compared with Zn-bound mimics. Detailed electrochemical, kinetic and vibrational spectroscopic
studies, in tandem with theoretical density functional theory calculations, demonstrate that the non-haem metal not only
donates electrons to oxygen but also activates it for efficient O–O bond cleavage. Furthermore, the higher redox potential
of copper and the enhanced weakening of the O–O bond from the higher electron density in the d orbital of copper are
central to its higher oxidase activity over iron. This work resolves a long-standing question in bioenergetics, and renders a
chemical–biological basis for the design of future oxygen-reduction catalysts.
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