title: [Spectroscopic characterization of binding between human serum albumin and 3,3', 4',7-tetrahydroxyflavone].
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.
authors.affiliation: Key Laboratory of Vegetation Ecology, MOE, Northeast Normal University, Changchun 130024, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Su
authors.forename: Meng-Xiaz
authors.initials: MX
authors.lastname: Xie
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Li
authors.forename: Ying-Dian
authors.initials: YD
authors.lastname: Wang
mesh_terms: D000042:Absorption; D005419:Flavonoids / Q000378:metabolism*; D044948:Flavonols; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011485:Protein Binding; D011522:Protons; D012709:Serum Albumin / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005419:Flavonoids; D044948:Flavonols; D011522:Protons; D012709:Serum Albumin; D012997:Solvents; C017875:fisetin