Study on the Interaction of Raloxifene and Bovine Serum Albumin by the Tachiya Model

Abstract

The interaction of bovine serum albumin (BSA) with raloxifene was assessed via fluorescence spectroscopy. The number of binding sites and the apparent binding constants between raloxifene and BSA were analyzed using the Tachiya model and Stern-Volmer equation, respectively. The apparent binding constant and the number of binding sites at 298 K were 2.33×105 L⋅mol−1 and 1.0688 as obtained from the Stern-Volmer equation and 2.00×105 L⋅mol−1 and 2.6667 from the Tachiya model. The thermodynamic parameters ΔH and ΔS were calculated to be 69.46 kJ⋅mol−1 and 121.12 J⋅K−1⋅mol−1, respectively, suggesting that the force acting between raloxifene and BSA was mainly a hydrophobic interaction. The binding distance between the donor (BSA) and acceptor (raloxifene) was 4.77 nm according to Forster’s nonradiational energy transfer theory. It was also found that common metal ions such as K+, Cu2+, Zn2+, Mg2+ and Ca2+ decreased the apparent association constant and the number of binding sites between raloxifene and BSA.