Analysis of Binding Interaction Between Prulifloxacin and Pepsin in the Existence of Eu(III): A Spectroscopic Analysis

Xiaoyan      Gao; Xiaojie      Zhang; Yingcai      Tang; Xiaoping      Zhang; Wujie      Zhao; Yanqin      Zi

doi:10.2174/1573411011107030194

Abstract

Interaction between prulifloxacin (PUFX) and pepsin was studied under a simulated physiological condition using fluorescence spectrophotometric techniques when the Eu(III) exists. The fluorescence emission intensity of pepsin was strongly quenched by the addition of prulifloxacin. Spectrophotometric observations are rationalized in terms of a static quenching process. The binding constants and the number of binding sites have been evaluated by the data obtained from the fluorescence quenching experiments. According to the vant Hoff equation, the standard enthalpy change (ΔH°) and standard entropy change (ΔS°) for the reaction were calculated and it indicated that the hydrophobic interactions play a main role in the binding of PUFX and pepsin. In addition, the binding distance R between pepsin (donor) and PUFX (acceptor) was obtained on the basis of the Forsters resonance energy transfer theory. The results obtained herein show that the interaction between the pepsin and PUFX was not influenced by Eu(III).

Keywords: PUFX, Pepsin, Fluorescence quenching, Binding constant, Eu(III), Binding Interaction, Spectroscopic Analysis, van, ’, t Hoff equation, Standard enthalpy change, Standard entropy change, Förster, s resonance energy transfer theory