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Heat-induced changes in lupin seed γ-conglutin structure promote its interaction with model phospholipid membranes
Influence of temperature on secretion and functionality of lupin seed γ‐conglutin
AbstractBACKGROUNDBasic 7S globulins, a group of proteins commonly found in legumes, undergo the intriguing phenomenon of release from the seeds into hot water. γ‐Conglutin is a representative of this group of proteins found in lupin seeds. The physiological significance and the molecular mechanism of the selective release of γ‐conglutin from lupin seeds remain unknown. Therefore, the presented study aimed to determine changes in the functionality of this protein in response to the high temperature occurring during lupin seed incubation.RESULTSIt was confirmed that the main protein fraction released from the seeds during high‐temperature incubation was γ‐conglutin. The incubation condition favours the occurrence of this protein in a monomeric form, and the temperature used corresponds to its midpoint unfolding temperature. Subsequent analysis carried out on the γ‐conglutin monomer revealed changes in its functionality after heat shock. The thermally treated protein shows a considerable increase in its interaction strength with flavonoids. Moreover, the inhibitory activity against glycoside hydrolases was enhanced when γ‐conglutin monomer was exposed to specific temperatures.CONCLUSIONThe results of the present study provide a potential explanation of the physiological relevance of γ‐conglutin and shed new light on a possible mechanism of its activation upon specific heat treatment. This knowledge will help characterise homologous proteins, which are commonly found in other legumes and undergo a similar heat‐induced secretion phenomenon. © 2021 Society of Chemical Industry.
Characteristics of N-Glycosylation and its Impact on the molecular behavior of lupinus angustifolius γ-Conglutin
Effect of different oligomerization assemblies of γ-conglutin on its interaction behavior with vitexin
AbstractBACKGROUNDSeveral different factors underlie the molecular mechanisms of phenolic compound‐protein interactions. They include the environmental conditions. In the case of γ‐conglutin, pH conditions translate directly into the adoption of two distinct oligomeric assemblies, i.e. hexameric (pH 7.5) or monomeric (pH 4.5). This paper reports research on the pH‐dependent oligomerization of γ‐conglutin in terms of its ability to form complexes with a model flavonoid (vitexin).RESULTSFluorescence‐quenching thermodynamic measurements indicate that hydrogen bonds, electrostatic forces, and van der Waals interactions are the main driving forces involved in the complex formation. The interaction turned out to be a spontaneous and exothermic process. Assessment of structural composition (secondary structure changes and arrangement/dynamics of aromatic amino acids), molecular size, and the thermal stability of the different oligomeric forms showed that γ‐conglutin in a monomeric state was less affected by vitexin during the interaction.CONCLUSIONThe data show precisely how environmental conditions might influence phenolic compound‐protein complex formation directly. This knowledge is essential for the preparation of food products containing γ‐conglutin. The results can contribute to a better understanding of the detailed fate of this unique health‐promoting lupin seed protein after its intake. © 2023 Society of Chemical Industry.