title: Differences in heat stability and ligand binding among β-lactoglobulin genetic variants A, B and C using (1)H NMR and fluorescence quenching.
abstract: The structure of β-lactoglobulin (β-LG) is well characterized, but the exact location of binding sites for retinol and (-)-epigallocatechingallate (EGCG) is still a subject of controversy. Here we report that the genetic β-LG variants A, B and C have different numbers of binding sites for retinol (almost completely incorporated into the calyx), as well as for EGCG (exclusively bound on the surface), and β-LG A with the most binding sites for EGCG, which include Tyr(20), Phe(151) and His(59). Upon heat related unfolding, new unspecific binding sites emerge, which are comparable in number and affinity for retinol and for EGCG, and in the three genetic variants A, B and C. The findings of our study provide new insights into the use of β-LG as nanotransporter.
authors.affiliation: Christian-Albrechts-Universität zu Kiel, Department of Food Technology, Institute of Human Nutrition and Food Science, Heinrich-Hecht Platz 10, D-24118 Kiel, Germany. Electronic address: jkeppler@foodtech.uni-kiel.de.
authors.forename: Julia K
authors.initials: JK
authors.lastname: Keppler
authors.affiliation: Christian-Albrechts-Universität zu Kiel, Otto Diels Department of Organic Chemistry, Otto-Hahn Platz 4, D-24098 Kiel, Germany. Electronic address: fsoennichsen@oc.uni-kiel.de.
authors.forename: Frank D
authors.initials: FD
authors.lastname: Sönnichsen
authors.affiliation: Max Rubner-Institut, Department of Safety and Quality of Milk and Fish Products, Hermann-Weigmann-Straße 1, D-24103 Kiel, Germany. Electronic address: peter-christian.lorenzen@mri.bund.de.
authors.forename: Peter-Christian
authors.initials: PC
authors.lastname: Lorenzen
authors.affiliation: Christian-Albrechts-Universität zu Kiel, Department of Food Technology, Institute of Human Nutrition and Food Science, Heinrich-Hecht Platz 10, D-24118 Kiel, Germany. Electronic address: kschwarz-2@foodtech.uni-kiel.de.
authors.forename: Karin
authors.initials: K
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D001665:Binding Sites; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D002942:Circular Dichroism; D007700:Kinetics; D007782:Lactoglobulins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011485:Protein Binding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013050:Spectrometry, Fluorescence; D014801:Vitamin A / Q000737:chemistry*
chemical_list: D007782:Lactoglobulins; D014801:Vitamin A; D002392:Catechin; C045651:epigallocatechin gallate
keywords: Epigallocatechingallate binding; Fluorescence quenching; Genetic variant; Protein heat stability; Protein–ligand interaction; Retinol binding; β-Lactoglobulin