Outer-sphere effects on reduction potentials of copper sites in proteins: the curious case of high potential type 2 C112D/M121E Pseudomonas aeruginosa azurin

Lancaster, K. M., Sproules, S. , Palmer, J. H., Richards, J. H. and Gray, H. B. (2010) Outer-sphere effects on reduction potentials of copper sites in proteins: the curious case of high potential type 2 C112D/M121E Pseudomonas aeruginosa azurin. Journal of the American Chemical Society, 132(41), pp. 14590-14595. (doi:10.1021/ja105731x)

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Abstract

Redox and spectroscopic (electronic absorption, multifrequency electron paramagnetic resonance (EPR), and X-ray absorption) properties together with X-ray crystal structures are reported for the type 2 CuII C112D/M121E variant of Pseudomonas aeruginosa azurin. The results suggest that CuII is constrained from interaction with the proximal glutamate; this structural frustration implies a “rack” mechanism for the 290 mV (vs NHE) reduction potential measured at neutral pH. At high pH (9), hydrogen bonding in the outer coordination sphere is perturbed to allow axial glutamate ligation to CuII, with a decrease in potential to 119 mV. These results highlight the role played by outer-sphere interactions, and the structural constraints they impose, in determining the redox behavior of transition metal protein cofactors.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Sproules, Dr Stephen
Authors: Lancaster, K. M., Sproules, S., Palmer, J. H., Richards, J. H., and Gray, H. B.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of the American Chemical Society
Publisher:American Chemical Society
ISSN:0002-7863
ISSN (Online):1520-5126

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