title: Investigation of the interaction between quercetin and human serum albumin by multiple spectra, electrochemical impedance spectra and molecular modeling.
abstract: Quercetin (Qu), a flavonoid compound, exists widely in the human diet and exhibits a variety of pharmacological activities. This work is aimed at studying the effect of Qu on the bioactive protein, human serum albumin (HSA) under simulated biophysical conditions. Multiple spectroscopic methods (including fluorescence and circular dichroism), electrochemical impedance spectra (EIS) and molecular modeling were employed to investigate the interaction between Qu and HSA. The fluorescence quenching and EIS experimental results showed that the fluorescence quenching of HSA was caused by formation of a Qu-HSA complex in the ground state, which belonged to the static quenching mechanism. Based on the calculated thermodynamic parameters, it concluded that the interaction was a spontaneous process and hydrogen bonds combined with van der Waal's forces played a major role in stabilizing the Qu-HSA complex. Molecular modeling results demonstrated that several amino acids participated in the binding process and the formed Qu-HSA complex was stabilized by H-bonding network at site I in sub-domain IIA, which was further confirmed by the site marker competitive experiments. The evidence from circular dichroism (CD) indicated that the secondary structure and microenvironment of HSA were changed. Alterations in the conformation of HSA were observed with a reduction in the amount of α helix from 59.9% (free HSA) to 56% (Qu-HSA complex), indicating a slight unfolding of the protein polypeptides.
authors.affiliation: College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou, Hubei, 434023, People's Republic China.
authors.forename: Jie
authors.initials: J
authors.lastname: Dai
authors.forename: Ting
authors.initials: T
authors.lastname: Zou
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yezhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D017097:Electric Impedance; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011487:Protein Conformation; D011794:Quercetin / Q000737:chemistry* / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D012709:Serum Albumin; D011794:Quercetin
keywords: circular dichroism; fluorescence quenching; human serum albumin; molecular modeling; quercetin