Study on the Interaction between Pefloxacin Mesylate and Human Serum Albumin

Abstract

AbstractThe binding characteristics of pefloxacin mesylate (PFLX) and human serum albumin (HSA) have been studied by fluorescence spectroscopy in aqueous solution, and the interaction influenced by copper(II) was also explored in the paper. The results show that the two reaction equilibrium constant and the number of binding sites were K=1.7×105 L·mol−1, n=1.05 for PFLX and K=1.61×105 L·mol−1, n=1.5 for PFLX‐Cu2+, respectively. The quenching mechanism of fluorescence of HSA by PFLX is a static quenching procedure. The binding distance between PFLX and HSA and the energy transfer efficiency were obtained based on the theory of Förster spectroscopy energy transfer. The effect of pefloxacin mesylate on the conformation of HSA has also been analyzed by using synchronous fluorescence spectroscopy. The interaction of PFLX and HSA have been studied by flow‐mixed microcalorimetry in the absence and presence of copper(II), and their thermodynamic parameters were obtained. The enthalpy change and the entropy change were calculated to be ΔH≈0, ΔS>0 in the absence of copper(II), indicating that hydrophobic forces played major role in the interaction between PFLX and HSA, and to be ΔH<0, ΔS>>0 in the presence of copper(II), indicated that the static forces played major role in the reaction. The molar free energy changes of the two reactions are identical with each other because the entropy‐enthalpy compensation happened between the two reactions.