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Spectroscopy
Volume 26, Issue 3, Pages 195-201
http://dx.doi.org/10.3233/SPE-2011-0539

The interaction between protocatechuic aldehyde and human serum albumin using three-dimensional fluorescence techniques

Jing Tian,1 Changyun Chen,1,2 and Mengwei Xue1

1School of Biochemical and Environmental Engineering, Nanjing Xiaozhuang University, Nanjing, China
2School 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

The binding mechanism between protocatechuic aldehyde (PA) and human serum albumin (HSA) was investigated by fluorescence spectroscopy at different temperatures. It is proved that the fluorescence quenching of HSA by PA is not results of the formation of PA–HSA complex. The equilibrium constant K and the number of binding sites n were measured at different temperature by fluorescence quenching method. The standard enthalpy change (ΔH) and the standard entropy change (ΔS) of this interaction process were calculated to be 114.02 kJ · mol−1, 541.92 J · mol−1·K−1, respectively. According to the interaction between PA and HSA of thermodynamic parameters ΔH and ΔS, the major acting force can be measured. The synchronous fluorescence spectra shows the microenvironment of tryptophan residue is changed and the hydrophobicity is increased. Through three-dimensional (3D) fluorescence spectra can get some valuable structure changing information.