title: Probing the binding sites of resveratrol, genistein, and curcumin with milk β-lactoglobulin.
abstract: We determined the binding sites of curcumin (cur), resveratrol (res), and genistein (gen) with milk β-lactoglobulin (β-LG) at physiological conditions. Fourier transform infrared spectroscopy, circular dichroism, and fluorescence spectroscopic methods as well as molecular modeling were used to determine the binding of polyphenol-protein complexes. Structural analysis showed that polyphenols bind β-LG via both hydrophilic and hydrophobic contacts with overall binding constants of Kcurcumin-β-LG = 4.4 (± .4) × 10⁴ M⁻¹, Kresveratrol-β-LG = 4.2 (± .2) × 10⁴ M⁻¹, and Kgenistein-β-LG = 1.2 (± .2) × 10⁴ M⁻¹. The number of polyphenol molecules bound per protein (n) was 1 (cur), 1.1 (res), and 1 (gen). Molecular modeling showed the participation of several amino acid residues in polyphenol-protein complexation with the free binding energy of -12.67 (curcumin-β-LG), -12.60 (resveratrol-β-LG), and -10.68 kcal/mol (genistein-β-LG). The order of binding was cur > res > gen. Alteration of the protein conformation was observed in the presence of polyphenol with a major reduction of β-sheet and an increase in turn structure, causing a partial protein structural destabilization. β-LG might act as a carrier to transport polyphenol in vitro.
authors.affiliation: a Laboratory of Chemistry, Department of Science , Agricultural University of Athens , 75 Iera Odos, Athens , 11855 , Greece .
authors.forename: C D
authors.initials: CD
authors.lastname: Kanakis
authors.forename: P A
authors.initials: PA
authors.lastname: Tarantilis
authors.forename: M G
authors.initials: MG
authors.lastname: Polissiou
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002942:Circular Dichroism; D003474:Curcumin / Q000737:chemistry* / Q000378:metabolism; D019833:Genistein / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D007782:Lactoglobulins / Q000737:chemistry* / Q000378:metabolism; D008892:Milk / Q000378:metabolism; D008894:Milk Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D000077185:Resveratrol; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D013267:Stilbenes / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D007782:Lactoglobulins; D008894:Milk Proteins; D013267:Stilbenes; D019833:Genistein; D003474:Curcumin; D000077185:Resveratrol