Insights into the Mechanism of Quercetin against BSA-Fructose Glycation by Spectroscopy and High-Resolution Mass Spectrometry: Effect on Physicochemical Properties

Abstract

Quercetin has been reported to suppress protein glycation or the formation of advanced glycation end-products (AGEs), but the inhibition mechanism related to protein structure and glycation sites and the influence on physicochemical properties remain unclear. The aim of the current research was to investigate the mechanism of quercetin against glycation with BSA-fructose as model by spectroscopic and spectrometric techniques. Changes in physicochemical properties were evaluated by antioxidant activity and emulsifying properties. The results indicated that quercetin dose-dependently inhibited the glycation of BSA by attenuating the alteration of conformational structure and microenvironment induced by glycation. It could also suppress the cross-linking or aggregation of glycated BSA, which reflected in the decreased molecular weight determined by SDS-PAGE and MALDI-TOF. Nanoliquid chromatography coupled to Q-Exactive tandem mass spectrometry analysis revealed the mapping of 20, 23, 19, and 19 glycation sites in glycated BSA with 0, 0.5, 1.5, and 3.0 mM quercetin, respectively. Quercetin changed the glycation sites of BSA, but it could not reduce the number greatly. In addition, quercetin reduced the antioxidant ability and increased the emulsifying properties of BSA, while negligible efficiency was observed on the antioxidant activity and emulsifying activity index of glycated BSA.

Fructose and methylglyoxal-induced glycation alters structural and functional properties of salivary proteins, albumin and lysozyme

“…Besides, the appearance of a subtle but distinct band when compared to profile of non-glycated albumin suggested a possible correspondence with a tripolymer that emerged as an indication of crosslinking in glycated albumin. This type of observation has also been described in Zhang et al [112]. The electrophoretic profile of glycated lysozyme also showed formation of high molecular weight products in the presence of fructose and MGO, characterizing crosslinked lysozyme.…”

Binding of β-lactoglobulin to three phenolics improves the stability of phenolics studied by multispectral analysis and molecular modeling

“…This is due to the ability of QT to inhibit glycation-induced changes in conformational structure and microenvironment, which in turn inhibits BSA glycation. Moreover, QT can inhibit cross-linking or aggregation of glycated BSA, altering the glycation site of BSA ( Zhang et al, 2019 , Zhang et al, 2019 ).

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Effect of (E,E)‐2,4‐decadienal on Side‐Chain Modification, Conformation Change, and Aggregation of Bovine Serum Albumin

“…Tryptophan and tyrosine residues can generally be excited to emit fluorescence above 280 nm, while phenylalanine residues cannot be excited under normal conditions. [ 53 ] The fluorescence of tryptophan residues is very sensitive to changes in its vicinity; therefore, it is widely used to determine conformational changes in protein molecules. An excitation wavelength of 295 nm is used to avoid the fluorescence resonance energy transfer between tyrosine and tryptophan residues, but it only reflects the fluorescence characteristics of tryptophan residues.…”