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Updated: Nov 3, 2025

Covalent Labeling with Diethylpyrocarbonate for Studying Protein Higher-Order Structure by Mass Spectrometry
Published on: June 15, 2021
Effects of different dietary polyphenols on conformational changes and functional properties of protein-polyphenol
Xiangju Liu1, Qibin Song1, Xin Li1
1State Key Laboratory of Tea Plant Biology and Utilization, Key Laboratory of Food Nutrition and Safety, School of Tea & Food Science and Technology, Anhui Agricultural University, Hefei 230036, China.
Abstract:
In this study, conjugates of whey protein isolate (WPI) and four polyphenols (epigallocatechin gallate [EGCG], quercetin [QC], apigenin [AG], and naringenin [NG]) were prepared through free-radical grafting. The results for polyphenol binding equivalents and content of free amino and sulfhydryl groups as well as those from sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the covalent interaction between WPI and the polyphenols. Fourier transform infrared spectroscopy and fluorescence spectrum analysis identified the potential binding sites of the complexes and determined changes in the protein structure. The particle size distribution and scanning electron microscopy data demonstrated increases in conjugate particle sizes and surface changes in the complexes. The conjugation process significantly increased the polyphenols' antioxidant properties and thermal stabilities, whereas surface hydrophobicity was substantially reduced. WPI-EGCG had the best functional properties, followed by WPI-QC, WPI-AG, and WPI-NG.
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