Analytical Sciences

Interaction of Tetrandrine with Human Serum Albumin: a Fluorescence Quenching Study

Chun WANG,* Qiu-Hua WU,* Cai-Rui LI,** Zhi WANG,* Jing-Jun MA,* Xiao-Huan ZANG,* and Na-Xin QIN*

*College of Science, Agricultural University of Hebei, Baoding 071001, Hebei, China
**College of Vocational and Technological Sanitation, Hebei University, Baoding 071002, China

The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the Förster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K_A) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies.

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