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Spectroscopy
Volume 25, Issue 2, Pages 113-122
http://dx.doi.org/10.3233/SPE-2011-0498

Investigation of the mechanism of binding of thiacloprid to human serum albumin using spectroscopic techniques and molecular modeling methods

Chuanxian Wang,1 Qinghua Chu,1 Changyun Chen,2,4 and Zhao Bo3

1Shanghai Exit-Entry Inspection and Quarantine Bureau, Shanghai, China
2School of Biochemical and Environmental Engineering, Nanjing Xiaozhuang University, Nanjing, China
3School of Chemical and Material Science, Nanjing Normal University, Nanjing, China
4School of Biochemical and Environmental Engineering, Nanjing Xiaozhuang University, Nanjing-211171, China

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Fluorescence spectroscopy, UV absorption, circular dichroism (CD) spectroscopy and molecular modeling methods were used to characterize the binding properties of thiacloprid (TL) with human serum albumin (HSA) at molecular level under physiological conditions. The fluorescence intensity of HSA decreased regularly with the gradually increasing concentration of thiacloprid. The binding constant K at three different temperatures (290, 300 and 310 K) were 3.07, 2.74 and 1.35 × 104 M−1, respectively, for TL–HSA interaction have been calculated from the relevant fluorescence data. CD spectroscopic measurements have shown that the secondary structures of the protein have been changed by the interaction of thiacloprid with HSA. Furthermore, the study of molecular modeling indicated that thiacloprid could be located on the surface of the binding pocket of subdomains IIA in HSA. The hydrophobic interaction was the major acting force and there are H-bonds and electrostatic interactions between TL and HSA, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change ΔH0 and the entropy change ΔS0 were calculated to be -20.378 kJ/mol and 16.328 J/mol K according to the Van9t Hoff equation).