Characterization of structural and functional properties of soybean 11S globulin during renaturation after denaturation induced by pH.

Abstract

This study explored the denaturation of 11S globulin, a protein known for its diverse functionalities in soy protein applications, at pH 3.0 and pH 10.0, subsequently followed by a gradual return to pH 7.0 to facilitate renaturation. It investigated the structural and functional changes during renaturation induced by pH, unveiling the stabilization mechanism of 11S globulin. The findings revealed that during pH adjustment to neutral, the denatured soybean 11S globulin-resulting from alkaline (pH 10.0) or acidic (pH 3.0) treatments-experienced a refolding of its extended tertiary structure to varying extents. The particle size and the proportions of α-helix and β-sheet in the secondary structure progressively aligned with those of the natural state protein. However, for the alkali-denatured 11S, the β-sheet content decreased upon adjustment to neutral, whereas an increase was observed for the acid-denatured 11S. In terms of functional properties, after alkaline denaturation, the foaming capacity (FC) and emulsifying activity index (EAI) of 11S increased by 1.4 and 1.2 times, respectively, compared to its native state. The solubility, foamability, and emulsifiability of the alkali-denatured 11S gradually diminished during renaturation but remained superior to those of the native state. Conversely, these properties showed an initial decline, followed by an increase during renaturation triggered by pH neutralization. This research contributes to the enhancement of protein functionality, offering a theoretical foundation for the development of functional soy protein products and expanding their potential applications. This article is protected by copyright. All rights reserved.