Coordination effects on the electronic structure of the CuA site of cytochrome c oxidase

The CuA site is the electron mediator in cytochrome c oxidase (CcO), providing an appropriate electronic structure for rapid electron transfer. We have studied the coordinating effects of His, Met, and the peptide carbonyl group of Glu of the CuA site, using the density functional theory. Our computation demonstrates that the His ligation provides strong orbital and electrostatic effects on the electronic structure of the CuA site, while that the Met coordination gives weak orbital and electrostatic effects. A coordination of the peptide carbonyl group affects the electronic structure of the CuA site only electrostatically.