Salem Faham1, Michael W. Day, William B. Connick, Brian R. Crane, Angel J. Di Bilio, W. P. Schaeffer, Douglas C. Rees, Harry B. Gray
1Division of Chemistry and Chemical Engineering, 147-75 CH, California Institute of Technology, Pasadena, California 91125, USA.
Tóm tắt
The crystal structure of Ru(2,2′-bipyridine)2(imidazole)(His83)azurin (RuAz) has been determined to 2.3 Å resolution by X-ray crystallography. The spectroscopic and thermodynamic properties of both the native protein and [Ru(2,2′-bipyridine)2(imidazole)2]2+ are maintained in the modified protein. Dark-green RuAz crystals grown from PEG 4000, LiNO3, CuCl2 and Tris buffer are monoclinic, belong to the space group C2 and have cell parameters a = 100.6, b = 35.4, c = 74.7 Å and β = 106.5°. In addition, [Ru(2,2′-bipyridine)2(imidazole)2]SO4·10H2O was synthesized, crystallized and structurally characterized by X-ray crystallography. Red–brown crystals of this complex are monoclinic, space group P21/n, unit-cell parameters a = 13.230 (2), b = 18.197 (4), c = 16.126 (4) Å, β = 108.65 (2)°. Stereochemical parameters for the refinement of Ru(2,2′-bipyridine)2(imidazole)(His83) were taken from the atomic coordinates of [Ru(2,2′-bipyridine)2(imidazole)2]2+. The structure of RuAz confirms that His83 is the only site of chemical modification and that the native azurin structure is not perturbed significantly by the ruthenium label.
