The Conformational Structural Change of Soy Glycinin via Lactic Acid Bacteria Fermentation Reduced Immunoglobulin E Reactivity

Abstract

This study investigated the fermentation of isolated soy glycinin by using the Lactiplantibacillus plantarum B1-6 strain, its reduction effect on immunoglobulin E (IgE) reactivity, the relationship with protein aggregation/gelation state and conformational changes. Fermentation was performed under different glycinin concentrations (0.1%, 0.5%, 1% and 2%, w/v) and varied fermentation terminal pH levels (FT-pH) (pH 6.0, 4.5, 4.0 and 3.5). L. plantarum B1-6 showed potency in reducing immunoreactivity to 0.10–69.85%, as determined by a sandwich enzyme-linked immunosorbent assay. At a FT-pH of 6.0 and 4.5, extremely low IgE reactivity (0.1–22.32%) was observed. Fermentation resulted in a great increase (2.31–6.8-fold) in particle size and a loss of intensity in A3 and basic subunits. The conformation of glycinin was altered, as demonstrated by improved surface hydrophobicity (1.33–7.39-fold), decreased intrinsic fluorescence intensity and the α-helix structure. Among the four selected concentrations, glycinin at 1% (w/v, G-1) evolved the greatest particles during fermentation and demonstrated the lowest immunoreactivity. Principal component analysis confirmed that particle size, intrinsic fluorescence intensity, α-helix and ionic bond were closely related to immunoreactivity reduction.

Lactic acid bacteria modulate the gastrointestinal digestive behavior of soy glycinin and correlation with its immunoreactivity: a peptidomic study

“…This might lead to the exposure of allergenic epitope degradation sites, thereby increasing the intensity of epitope degradation. 9 After 180 min of digestion, epitope-degradation frequency decreased. The most obvious reduction occurred in epitopes with β-sheet and α-helix structures.…”

“…6 Our previous research has revealed that Lactobacillus plantarum B1-6 fermentation significantly reduces the antigenicity of glycinin, and the effect varies with the glycinin concentration and fermentation terminal pH. 9…”

“…6 Our previous research has revealed that Lactobacillus plantarum B1-6 fermentation significantly reduces the antigenicity of glycinin, and the effect varies with the glycinin concentration and fermentation terminal pH. 9 A critical requirement for a protein to exert allergenicity depends on its stability in gastrointestinal digestion. Only epitopes that remain intact after gastrointestinal digestion and exposed in the duodenal tract may have the chance to move across the mucosa and bind to IgE, thereby potentially inducing allergic reactions.…”

“…14 Our previous study has demonstrated dramatically decreased immunoreactivity in FG due to the capacity of the Lactobacillus plantarum B1-6 to open protein secondary and tertiary structures. 9 Peptidomics is a valuable tool for the identification and analysis of the peptidomic profile. Combined with bioinformatics and the Immune Epitope Database, the alteration, modification, and degradation profiles of the epitopes can be illustrated.…”