Structural changes at the copper centre of Azurin in an oxidation-reduction process: an integrated approach combining crystallography and EXAFS

Abstract

Crystallographic structures of oxidised and reduced forms of azurin II are reported at 1.75~ resolution [1]. Data were collected using one crystal in each case and by translating crystal after each oscillation range to minimise photo-reduction. Very small differences are observed at the Cu site upon reduction and that these cannot be determined with confidence at current resolution. A comparison with the 3D EXAFS reveals a good correspondence for all the ligands distances except for CuHis46 where a larger deviation of ~0.12-0.18~ is observed indicating that this ligand is more tightly restrained in the crystallographic refinement at the current resolution. Three dimensional information is obtained for the Cu site in azurin [2] at very high resolution by combining high resolution crystallographic structures and EXAFS data for the oxidised and reduced form of the protein. This combined approach has allowed us to define the subtle structural changes (<0.1~) which take place at the Cu site during a single electron redox process. s8a.m7.p14.la Crystal structure of the Stromelysin-3 complexed with a phosphinic inhibitor reveals that its S 1 ' pocket is a deep opened cavity. A