title: Binding affinity between dietary polyphenols and β-lactoglobulin negatively correlates with the protein susceptibility to digestion and total antioxidant activity of complexes formed.
abstract: Non-covalent interactions between β-lactoglobulin (BLG) and polyphenol extracts of teas, coffee and cocoa were studied by fluorescence and CD spectroscopy at pH values of the gastrointestinal tract (GIT). The biological implications of non-covalent binding of polyphenols to BLG were investigated by in vitro pepsin and pancreatin digestibility assay and ABTS radical scavenging activity of complexes formed. The polyphenol-BLG systems were stable at pH values of the GIT. The most profound effect of pH on binding affinity was observed for polyphenol extracts rich in phenolic acids. Stronger non-covalent interactions delayed pepsin and pancreatin digestion of BLG and induced β-sheet to α-helix transition at neutral pH. All polyphenols tested protected protein secondary structure at an extremely acidic pH of 1.2. A positive correlation was found between the strength of protein-polyphenol interactions and (a) half time of protein decay in gastric conditions (R(2)=0.85), (b) masking of total antioxidant capacity of protein-polyphenol complexes (R(2)=0.95).
authors.affiliation: University of Belgrade, Faculty of Chemistry, Belgrade, Serbia.
authors.forename: Marija
authors.initials: M
authors.lastname: Stojadinovic
authors.forename: Jelena
authors.initials: J
authors.lastname: Radosavljevic
authors.forename: Jana
authors.initials: J
authors.lastname: Ognjenovic
authors.forename: Jelena
authors.initials: J
authors.lastname: Vesic
authors.forename: Ivana
authors.initials: I
authors.lastname: Prodic
authors.forename: Dragana
authors.initials: D
authors.lastname: Stanic-Vucinic
authors.forename: Tanja
authors.initials: T
authors.lastname: Cirkovic Velickovic
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D004063:Digestion; D041981:Gastrointestinal Tract / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007782:Lactoglobulins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D059808:Polyphenols / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D000975:Antioxidants; D007782:Lactoglobulins; D059808:Polyphenols