Reaction of the Anticancer Organometallic Ruthenium Compound, [(η6-p-Cymene)Ru(ATSC)Cl]PF6 with Human Serum Albumin

Abstract

The reaction of [(η6-p-cymene)Ru(ATSC)Cl]PF6 (ATSC =9-anthraldehyde thiosemicarbazone) with human serum albumin was investigated at different temperatures using fluorescence and infrared spectrophotometry. The binding constant, K, for the reaction was determined using a number of different methods. Using a modified Stern-Volmer equation, K was determined to be 9.09×104,12.1×104, and 13.1×104 M−1 at 293 K, 298 K, and 308 K, respectively. A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy of reaction ΔH=16.5 kJ mol−1 and the entropy of reaction ΔS=152 Jmol−1K−1. The values of ΔH and ΔS suggest that hydrophobic forces are dominant in the mode of interaction and that the process is mostly entropy driven.