Novel insights into the interaction mechanism of 5-hydroxymethyl-2-furaldehyde with β-casein and its effects on the structure and function of β-casein

Abstract

Abstract 5−Hydroxymethyl−2−furaldehyde (5-HMF) in dairy food products generated via Maillard reaction may bring health risks. Herein, the interaction of 5-HMF with β-casein (β-CN) and its influences on the structure and function of β-CN were investigated. 5-HMF was found to quench the inherent fluorescence of β-CN by a static mode and the binding constant was in the order of magnitude of 104\u202fL\u202fmol−1. Thermodynamic analysis indicated that hydrophobic forces played the major role in the interaction. The results of synchronous and three-dimensional fluorescence revealed that 5-HMF changed the microenvironment of tyrosine and tryptophan residues and interfered the stability of the polypeptide backbone structure in β-CN. Molecular docking revealed that 5-HMF bound to the hydrophobic cavity of β-CN mainly interacting with the amino acid residues Pro196, Val155, Leu163, Phe157 and Leu192. The binding of 5-HMF with β-CN caused partial unfolding of β-CN conformation, resulting in the increase in surface hydrophobicity and emulsifiability, and decrease in emulsification stability of β-CN, thereby reducing the solubility of β-CN. The study might facilitate the comprehensive understanding of 5-HMF affecting the structure and functional properties of β-CN.