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Chemistry. 2017 Nov 2;23(61):15436-15445. doi: 10.1002/chem.201702901. Epub 2017 Sep 21.

Prediction of Reduction Potentials of Copper Proteins with Continuum Electrostatics and Density Functional Theory.

Author information

1
Manchester Institute of Biotechnology and School of Chemistry, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.
2
Manchester Institute of Biotechnology and School of Materials, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.
3
Manchester Institute of Biotechnology, and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom.

Abstract

Blue copper proteins, such as azurin, show dramatic changes in Cu2+ /Cu+ reduction potential upon mutation over the full physiological range. Hence, they have important functions in electron transfer and oxidation chemistry and have applications in industrial biotechnology. The details of what determines these reduction potential changes upon mutation are still unclear. Moreover, it has been difficult to model and predict the reduction potential of azurin mutants and currently no unique procedure or workflow pattern exists. Furthermore, high-level computational methods can be accurate but are too time consuming for practical use. In this work, a novel approach for calculating reduction potentials of azurin mutants is shown, based on a combination of continuum electrostatics, density functional theory and empirical hydrophobicity factors. Our method accurately reproduces experimental reduction potential changes of 30 mutants with respect to wildtype within experimental error and highlights the factors contributing to the reduction potential change. Finally, reduction potentials are predicted for a series of 124 new mutants that have not yet been investigated experimentally. Several mutants are identified that are located well over 10 Å from the copper center that change the reduction potential by more than 85 mV. The work shows that secondary coordination sphere mutations mostly lead to long-range electrostatic changes and hence can be modeled accurately with continuum electrostatics.

KEYWORDS:

azurin; copper; density functional theory; protein electrostatics; redox

PMID:
28815759
PMCID:
PMC5698706
DOI:
10.1002/chem.201702901
[Indexed for MEDLINE]
Free PMC Article

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