Studies on the interactions between human serum albumin and imidazolium [trans-tetrachlorobis (imidazol) ruthenate(III)]

The interactions between imidazolium [trans-tetrachlorobis(imidazol)ruthena te(III)] (Ru-im) and human serum albumin (HSA) have been investigated throu gh UV-Vis, CD, fluorescence spectroscopy and by the antibody precipitation test. Binding of Ru(III)-imidazole species to albumin has a strong impact o n the protein structure and influences considerably the albumin binding of other molecules such as warfarin or heme. The metal complex-HSA interaction s cause conformational changes with the loss of helical stability of the pr otein and local perturbation in the domain IIA binding pocket. The relative fluorescence intensity of the ruthenium-bound HSA decreased, suggesting th at perturbation around the Trp 214 residue took place. This was confirmed b y the destabilisation of the warfarin binding site which includes Trp 214, observed in the metal-bound HSA. (C) 1999 Elsevier Science Inc. All rights reserved.