title: Characterization of flavonoid-protein interactions using fluorescence spectroscopy: Binding of pelargonidin to dairy proteins.
abstract: In this study, the interaction between the flavonoid pelargonidin and dairy proteins: β-lactoglobulin (β-LG), whey protein (WPI), and caseinate (CAS) was investigated. Fluorescence experiments demonstrated that pelargonidin quenched milk proteins fluorescence strongly. However, the protein secondary structure was not significantly affected by pelargonidin, as judged from far-UV circular dichroism. Analysis of fluorescence data indicated that pelargonidin-induced quenching does not arise from a dynamical mechanism, but instead is due to protein-ligand binding. Therefore, quenching data were analyzed using the model of independent binding sites. Both β-LG and CAS, but not WPI, showed hyperbolic binding isotherms indicating that these proteins firmly bound pelargonidin at both pH 7.0 and 3.0 (binding constants ca. 1.0×10(5) at 25.0°C). To investigate the underlying thermodynamics, binding constants were determined at 25.0, 35.0, and 45.0°C. These results pointed to binding processes that depend on the structural conformation of the milk proteins.
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Cuajimalpa, D.F. 05300, Mexico. Electronic address: iarroyo@correo.cua.uam.mx.
authors.forename: Izlia J
authors.initials: IJ
authors.lastname: Arroyo-Maya
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Cuajimalpa, D.F. 05300, Mexico.
authors.forename: José
authors.initials: J
authors.lastname: Campos-Terán
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Iztapalapa, D.F. 09340, Mexico.
authors.forename: Andrés
authors.initials: A
authors.lastname: Hernández-Arana
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: David Julian
authors.initials: DJ
authors.lastname: McClements
mesh_terms: D000872:Anthocyanins / Q000032:analysis / Q000378:metabolism*; D001665:Binding Sites / Q000502:physiology; D002364:Caseins / Q000032:analysis / Q000378:metabolism; D002942:Circular Dichroism / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000032:analysis / Q000378:metabolism*; D007782:Lactoglobulins / Q000032:analysis / Q000378:metabolism; D008894:Milk Proteins / Q000032:analysis / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence / Q000379:methods; D000067816:Whey Proteins / Q000032:analysis / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D002364:Caseins; D005419:Flavonoids; D007782:Lactoglobulins; D008894:Milk Proteins; D000067816:Whey Proteins; C066957:pelargonidin
keywords: Anthocyanins; Flavonoids; Fluorescence; Milk proteins; Pelargonidin; Sodium caseinate; Whey protein isolate; β-Lactoglobulin