Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (01): 221-229.doi: 10.3866/PKU.WHXB20100107

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Comparison between Psoralen and Isopsoralen Binding to Human Serum Albumin

HE Wen-Ying, YAO Xiao-Jun, HU Zhi-De, CHEN Guang-Ying   

  1. College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, P. R. China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China; Hainan Provincal Key Laboratory of Tropical Pharmaceutical Herb Chemistry, Haikou 571158, P. R. China
  • Received:2009-07-15 Revised:2009-10-09 Published:2009-12-29
  • Contact: HE Wen-Ying


Two active components (psoralen and isopsoralen) of Chinese herbs having similar structures were studied. A combination of intrinsic fluorescence spectroscopy, ultraviolet (UV) spectroscopy, circular dichroism(CD), and Fourier transform-infrared (FT-IR) spectroscopy were used to characterize the binding between the two coumarins and human serumalbumin (HSA). The results fromdifferent spectra indicated qualitative and quantitative changes of the secondary structure of HSA. The thermodynamic functions, enthalpies (△H) and entropies (△S), were calculated from fluorescence titration experiments using Vant's Hoff equation. The binding constants and number of binding sites for the drug interactions of both drugs with HSA were evaluated using the relevant fluorescence data at different temperatures (296, 303, 310, and 318 K) and applying modified Stern-Volmer and Scatchard equations. Forster theory of dipole-dipole energy transfer was used to determine the distance between the protein residue and the bound drugs. The competitive experiments suggested that psoralen and isopsoralen bound strongly to HSA and the primary binding site for both drugs was located at site II of HSA.

Key words: Spectroscopy, Psoralen, Isopsoralen, Human serumalbumin, Binding


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