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Updated: May 14, 2026

LERLIC-MS/MS for In-depth Characterization and Quantification of Glutamine and Asparagine Deamidation in Shotgun Proteomics
Published on: April 9, 2017
Effect of enzymatic deamidation on the heat-induced conformational changes in whey protein isolate and its relation
Noriko Miwa1, Keiichi Yokoyama, Noriki Nio
1Institute for Innovation, Ajinomoto Co., Inc. , 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, 210-8681, Kanagawa, Japan.
Abstract:
The effect of protein-glutaminase (PG) on the heat-induced conformational changes in whey protein isolate (WPI) and its relation to gel properties was investigated. The structural properties of WPI treated with PG were examined by several analytical methods. The analysis of the fluorescence spectrum and the binding capacity of a fluorescent probe demonstrated that deamidation prevented the increase in the fluorescence intensity caused by subsequent heat treatment. Measurements of the molecular weight distribution of WPI showed that PG-treated WPI was not likely to polymerize even after heating. This is thought to be due to an increase in electrostatic repulsion between carboxylic acid groups and a decrease in the formation of disulfide bonds, which results in the decrease in heat-induced aggregation. The properties of heat-induced WPI gels were modified by deamidation. PG-treated WPI gels had a soft texture and a high water-holding capacity in the presence of salts.
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