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Updated: Oct 2, 2025

Author Spotlight: In Silico Creation and Impact of Carbonylated Amino Acids on Protein Structure and Function
Published on: April 26, 2024
Activation mechanism of whey protein isolate mediated by free radicals generated in the ascorbic acid/hydrogen
Liying Chen1, Xinan Xie1, Yan Li1
1College of Food Science, South China Agricultural University, Guangzhou 510642, Guangdong, China.
Abstract:
Free radical grafting is a promising method that has been used to modify whey protein isolate (WPI) using polyphenol and provides desirable functionalities, but the reaction mechanism is unclear. This work investigated the grafting mechanism of WPI - (-)-Epigallocatechin-3-gallate (EGCG) through experimental techniques and molecular docking. The results showed that only the ascorbic acid radical anion (Asc•-) is generated in the Asc/ H2O2 system. Asc•- removed hydrogen atoms from amino and sulfhydryl groups, resulting in a decrease in their content. Cystine, proline, methionine, and histidine were discerned to be the grafting sites between WPI and EGCG for more sensitiveness. Furthermore, Asc•- and •OH changed the secondary structure of WPI, but Asc•- further induced oxidative deamination of amino acids. Therefore, the grafting mechanism is presumed that the Asc•- catches hydrogen atoms in protein-sensitive amino acids and generates macromolecular radicals that induce the formation of WPI-EGCG graft.
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