pH-Dependent oligomerisation of γ-conglutin: A key element to understand its molecular mechanism of action
| Authors | |
|---|---|
| Year of publication | 2024 |
| Type | Article in Periodical |
| Magazine / Source | Food Hydrocolloids |
| MU Faculty or unit | |
| Citation | |
| Web | https://www.sciencedirect.com/science/article/pii/S0268005X23009323?via%3Dihub |
| Doi | http://dx.doi.org/10.1016/j.foodhyd.2023.109386 |
| Keywords | gamma-Conglutin; Lupin seed; Oligomerisation; Protein structure; Protein size and molecular weight; Nutraceutical protein |
| Description | Despite extensive research carried out on lupin seed gamma-conglutin neither its mechanism of action as a hypoglycaemic nutraceutical compound nor its physiological role for the plant has been unveil. This article revealed a pH-dependent reversible association/dissociation equilibrium involving monomer, dimer and hexamer of Lupinus angustifolius gamma-conglutin. The interaction between different oligomeric forms of this protein is reversible, and spectroscopic studies showed that the intact structure of gamma-conglutin was preserved under the tested environmental conditions tested (pH 4.5-7.5). The obtained results prove that the hexameric form was preferred under basic conditions and was stabilised by a number of bonds formed upon association of individual protomers. The simultaneous occurrence of several oligomeric forms at a given pH value was shown, and their share was strongly driven by protein concentration. The main changes in oligomerisation of gamma-conglutin take place in a pH range of 4.5-6.0, correlating with the pKa(R) values of the amino acid residues of His (6.0), Glu (4.1), and Asp (3.9). Moreover, a structural model of the protein in hexamer assembly was obtained based on small-angle X-ray scattering (SAXS) and negative staining cryo-electron microscopy (cryo-EM) analyses. The presented study provides essential knowledge about the colloidal dynamics and stability of gamma-conglutin in solution, improving our understanding of fundamental environmental factors that could affect the health-promoting activity of this lupin seed protein. |
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