Outer-sphere contributions to the electronic structure of type zero copper proteins

Lancaster, K.M., Zaballa, M.-E., Sproules, S. , Sundararajan, M., DeBeer, S., Richards, J.H., Vila, A.J., Neese, F. and Gray, H.B. (2012) Outer-sphere contributions to the electronic structure of type zero copper proteins. Journal of the American Chemical Society, 134(19), pp. 8241-8253. (doi:10.1021/ja302190r)

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Abstract

Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 copper proteins. In recent work, we have found that copper ET sites in proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Sproules, Dr Stephen
Authors: Lancaster, K.M., Zaballa, M.-E., Sproules, S., Sundararajan, M., DeBeer, S., Richards, J.H., Vila, A.J., Neese, F., 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

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