Combined spectroscopic, molecular docking and quantum mechanics study of β-casein and p-coumaric acid interactions following thermal treatment. (30th June 2018)

• Record Type: Journal Article
• Authors: Kaur, Jasmeet; Katopo, Lita; Hung, Andrew; Ashton, John; Kasapis, Stefan
• Is Part Of: Food chemistry. Volume 252(2018)
• Page Start: 163
• Page End: 170
• Publication Date: 2018-06-30
• Subjects: β-Casein -- p-Coumaric acid -- Molecular interactions -- Thermal processing; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2018.01.091
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: We studied solutions of β -casein with p -coumaric acid following UHT-like treatment. Thermal treatment produced binary complexes that were stabilised with hydrogen bonding. Thermal treatment also induced covalent interactions between protein and phenolic acid. Abstract: The molecular nature of interactions between β -casein and p -coumaric acid was studied following exposure of their solutions to ultra-high temperature (UHT at 145 °C). Interactions were characterised by employing multi-spectroscopic methods, molecular docking and quantum mechanics calculations. FTIR demonstrates that the ligand lies in the vicinity of the protein, hence inverting the absorbance spectrum of the complex. This outcome changes the conformational characteristics of the protein leading to a flexible and open structure that accommodates the phenolic microconstituent. Results are supported by UV–vis, CD and fluorescence quenching showing considerable shifts in spectra with complexation. Molecular docking indicates that there is at least a hydrogen bond between p -coumaric acid and the peptide backbone of isoleucine (Ile27). Quantum mechanics calculations further argue that changes in experimental observations are also due to a covalent interaction in the protein-phenolic adduct, which according to the best predicted binding pose involves the side chain of lysine 47.