The CuA site of cytochrome c oxidase

The recent exciting developments concerning the structure and function of the CuA site in cytochrome c oxidase (COX) and nitrous oxide reductase are reviewed. The XRD structures of a mitochondrial and a bacterial COX have been reported in 1995. In COX, the CuA centre is located in subunit II and is involved in electron transfer from a cytochrome c donor to the oxygen binding centre of the protein. The structural studies on the enzyme have revealed the coordination geometries of the many metal centres of COX, including the CuA site. A combination of spectroscopic and mutagenesis studies on the CuA centre led to the correct prediction of the structure of this unique copper centre. The construction of a CuA site in type 1 blue copper proteins is briefly discussed.