Studies on the interaction between human serum albumin and [Rh-2(OAc)(2)(bpy)(2)(H2O)(2)](OAc)(2)

Absorption, CD, fluorescence, and ICP(AES) methods were used to evaluate the interaction of [Rh-2(OAc)(2)(bpy)(2)(H2O)(2)](OAc)(2) with human serum albumin (HSA). The rhodium complex reads easily with HSA; the Rh atoms are coordinated to protein via the imidazole rings of His residues. When the protein was incubated for 24 h at 37 degrees C, the amount of rhodium was found to be similar to 7 mol per mol of HSA. Analysis of CD spectra showed the decreasing helix content to be about 15% in the metal-bound HSA. The relative fluorescence intensity of HSA bound with rhodium decreased to 20% of that of the native state, suggesting that perturbation around the Trp-214 residue took place. This was confirmed by the destruction of the warfarin binding site. The rhodium binding weakens the interaction of HSA with other molecules like heme or bilirubin. (C) 1997 Elsevier Science Inc.