Resolving the Mechanisms of Soy Glycinin Self-Coacervation and Hollow-Condensate Formation

Self-coacervation of animal-derived proteins has been extensively investigated while that of plant proteins remains largely unexplored. Here, we study the process of soy glycinin self-coacervation and transformation into hollow condensates. The protein hexameric structure composed of hydrophilic and hydrophobic polypeptides is crucial for coacervation. The process is driven by charge screening of the intrinsically disordered region of acidic polypeptides, allowing for weak hydrophobic interactions between exposed hydrophobic polypeptides. We find that the coacervate surface exhibits order, which stabilizes the coacervate shape during hollow-condensate formation. The latter process occurs via nucleation and growth of protein-poor phase in the coacervate interior, during which another ordered layer at the inner surface is formed. Aging enhances the stability of both coacervates and hollow condensates. Understanding plant protein coacervation holds promises for fabricating novel functional materials.