Jian Luo, James F. Wishart, and Stephan S. Isied
J. Am. Chem. Soc. 120, 12970-12971 (1998) [Find paper at ACS Publications]
Abstract:
Stereoselective covalent binding of the ruthenium complexes cis-[Ru(bpy)2(H2O)2]2+ (bpy = 2,2'-bipyridine) and cis-[Ru(dmbpy)2(H2O)2]2+ (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) to the surface His 33 residue and the more buried His 26 residues of Horse heart cytochrome c (Hh cyt c) to form large enantiomeric excess of D-[Ru(dmbpy)2(H2O)]-His 26-cyt c (38%), but little or no excess of D-[Ru(bpy)2(H2O)]-His 26-cyt c (6%). At the surface exposed His 33 site, equal entiomeric excess of L-[Ru(dmbpy)2(H2O)]-His 33-cyt c and L-[Ru(bpy)2(H2O)]-His 33-cyt c (34%) were observed. Isomer assignment for the ruthenium proteins were based on CD spectra of the corresponding small molecule ruthenium complexes. Different redox potentials were determined by voltammetry for the different isomers with current ratios consistent with the CD spectral assignments. The rate of substitution of imidazole, which proceeds with retention of configuration, at the ruthenium site vary by as large as a factor of seven for Ru(bpy)2(H2O)]-His 26-cyt c D and L isomers.