Effects of Baicalein and Chrysin on the Structure and Functional Properties of β-Lactoglobulin

Abstract

Two flavonoids with similar structures, baicalein (Bai) and chrysin (Chr), were selected to investigate the interactions with β-lactoglobulin (BLG) and the influences on the structure and functional properties of BLG by multispectral methods combined with molecular docking and dynamic (MD) simulation techniques. The results of fluorescence quenching suggested that both Bai and Chr interacted with BLG to form complexes with the binding constant of the magnitude of 105 L·mol−1. The binding affinity between BLG and Bai was stronger than that of Chr due to more hydrogen bond formation in Bai–BLG binding. The existence of Bai or Chr induced a looser conformation of BLG, but Chr had a greater effect on the secondary structure of BLG. The surface hydrophobicity and free sulfhydryl group content of BLG lessened due to the presence of the two flavonoids. Molecular docking was performed at the binding site of Bai or Chr located in the surface of BLG, and hydrophobic interaction and hydrogen bond actuated the formation of the Bai/Chr–BLG complex. Molecular dynamics simulation verified that the combination of Chr and BLG decreased the stability of BLG, while Bai had little effect on it. Moreover, the foaming properties of BLG got better in the presence of the two flavonoids compounds and Bai improved its emulsification stability of the protein, but Chr had the opposite effect. This work provides a new idea for the development of novel dietary supplements using functional proteins as flavonoid delivery vectors.

Effect of transglutaminase in conjunction with glucono‐δ‐lactone treatment on the antigenicity and conformational structure of β‐conglycinin

“…The ANS is commonly used as a probe for assessing the surface hydrophobicity of proteins. While its fluorescence intensity is subtle in aqueous solutions, a significant augmentation occurs upon binding to the hydrophobic regions of proteins (Li et al ., 2022b). Assessing the surface hydrophobicity of proteins facilitates the examination of functional changes resulting from conformational alterations.…”

Noncovalent interaction mechanism and functional properties of flavonoid glycoside-β-lactoglobulin complexes

“…As described above, protein-flavonoids complexes reduced the surface hydrophobicity of the protein; thus, the hydrophilicity of the protein was enhanced, the speed and ability to adsorb at the oil–water interface were increased, protein aggregation was harder, and the surface tension of the emulsion was lower, eventually leading to increased EAI and ESI. 38,40…”

“…Li et al 7 and Ye et al 37 reported that flavonoids ( procyanidins or ruin) can improve the foaming properties of proteins. In addition, Li et al 38 suggested that the looser the protein, the better the foaming property. As the results described for the secondary structure content of protein, the interaction of the selected flavonoids with β-LG makes the structure of the protein looser; correspondingly, the foaming properties become stronger.…”

“…As described above, protein-flavonoids complexes reduced the surface hydrophobicity of the protein; thus, the hydrophilicity of the protein was enhanced, the speed and ability to adsorb at the oil-water interface were increased, protein aggregation was harder, and the surface tension of the emulsion was lower, eventually leading to increased EAI and ESI. 38,40 3.6.3 Antioxidative performance of the complexes. The antioxidation of flavonoids in food is mainly used in the prevention, intervention, and treatment of chronic diseases, which is of great significance for the improvement of human health.…”

Beta-Lactoglobulin as a Model Food Protein: How to Promote, Prevent, and Exploit Its Unfolding Processes

“…Polyphenols from a number of sources have been found to bind on the external surface of the protein with binding constants in the 10 3 –10 5 M −1 range, as calculated from the quenching of Trp19 fluorescence, and as also suggested by insilico docking studies. Computational approaches confirmed that flavonoids preferentially bind on the outer surface of BLG, mostly through hydrogen bonds and Van der Waals forces [ 16 , 46 ], and that the groove between the strand B and the C-terminus may represent a preferential binding site for several of these species [ 47 ]. At neutral pH, cocoa and coffee polyphenols were reported to induced structural destabilization of BLG, with a decrease in the β-sheet secondary structure in favor of α-helixes, and a concomitant increased susceptibility to pancreatin digestion.…”