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Updated: Jul 5, 2026

A Rapid and Quantitative Fluorimetric Method for Protein-Targeting Small Molecule Drug Screening
Published on: October 16, 2015
[Spectroscopic characterization of binding between human serum albumin and 3,3', 4',7-tetrahydroxyflavone]
Zhong Su1, Meng-Xiaz Xie, Jian-Dong Li
1Key Laboratory of Vegetation Ecology, MOE, Northeast Normal University, Changchun 130024, China.
Abstract:
The binding mechanism of human serum albumin with 3,3', 4', 7-tetradroxyflavone (FIS) was characterized by fluorescence and UV absorption spectra. The intrinsic fluorescence of HSA was significantly quenched by FIS in the physiological condition (pH 7.4), and the quenching mechanism is mainly static quenching process in the drug to protein molar ratio ranging from 0.1 to 10. The results revealed that the drug and protein formed 1 : 1 complex with the binding constants of (1.05 +/- 0.18) x 10(5) L x mol(-1). The dissociation behaviors of FIS in different pH conditions were investigated by UV absorption spectra, and it was found that FIS existed in the mixtures of ionic and neutral species. The UV absorption band I of FIS has a significant red shift (above 40 nm) after combination with HSA, demonstrating that FIS was bound to protein in ionic species which was driven by electrostatic force. The second derivative spectra of FIS showed that the combination included specific and non-specific forms. The intrinsic fluorescence of FIS was conspicuously enhanced in the presence of HSA due to the excited-state proton transfer (ESPT) and this further confirmed the complex formation of HSA with FIS.
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