title: Characterization and modeling of the interactions between coffee storage proteins and phenolic compounds.
abstract: This study addresses the interactions of coffee storage proteins with coffee-specific phenolic compounds. Protein profiles of Coffea arabica and Coffea canephora (var. robusta) were compared. Major phenolic compounds were extracted and analyzed with appropriate methods. The polyphenol-protein interactions during protein extraction have been addressed by different analytical setups [reversed-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS), and Trolox equivalent antioxidant capacity (TEAC) assays], with focus directed toward identification of covalent adduct formation. The results indicate that C. arabica proteins are more susceptible to these interactions and the polyphenol oxidase activity seems to be a crucial factor for the formation of these addition products. A tentative allocation of the modification type and site in the protein has been attempted. Thus, the first available in silico modeling of modified coffee proteins is reported. The extent of these modifications may contribute to the structure and function of "coffee melanoidins" and are discussed in the context of coffee flavor formation.
authors.affiliation: Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Potsdam, Germany.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Ali
authors.forename: Thomas
authors.initials: T
authors.lastname: Homann
authors.forename: Janka
authors.initials: J
authors.lastname: Kreisel
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Khalil
authors.forename: Ralf
authors.initials: R
authors.lastname: Puhlmann
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Kruse
authors.forename: Harshadrai
authors.initials: H
authors.lastname: Rawel
mesh_terms: D002851:Chromatography, High Pressure Liquid; D040503:Coffea / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D010636:Phenols / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D011485:Protein Binding; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010636:Phenols; D010940:Plant Proteins