Type-1 copper centers belong to the family of metal-containing oxidoreductases, where the redox active moiety is a copper ion bound in a nitrogen-sulfur donor environment. These metallosites, commonly known as blue-copper proteins, act as electron mediators within electron transport chains as the copper shuttles between Cu(I) and Cu(II) states. One critical element of the redox chemistry of type-1 copper sites is the display of a large variation (between 200 -1000 mV) in the Cu(I/II) redox potential, which translates into a Gibbs free energy difference of 18 kcal/mol. The cause of this huge fluctuation is unclear and only speculated to be due to active site hydrophobicity, axial ligation, and outer sphere coordination. In order to gain an insight into the role of protein matrix on the redox potentials of the copper center, we are using combined quantum mechanical/molecular mechanical simulation. The copper center and the atoms within its primary coordination sphere are treated with density functional theory, while embedded in a molecular mechanically treated region. Results of these studies on model systems as well as type-I proteins will be presented.

Calculation of redox potentials of type-I blue copper proteins using quantum mechanical/molecular mechanical simulations

245th National Meeting (2013)

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