Intellectual merit: Biomolecular assembly processes involving a competition between specific intermolecular interactions and thermodynamic phase instability have been implicated in a number of pathological states and technological applications of biomaterials. This work studied polypeptide mixtures and revealed unexpectedly diverse morphologies ranging from partially coalescing and aggregated droplets to bulk precipitates, as well as a previously unreported reentrant liquid−liquid phase separation at high polypeptide concentration and ionic strength. All-atom molecular dynamics simulations of folded polypeptide complexes revealed a concentration dependence of β-sheet-rich secondary structure whose relative composition correlates with the observed macroscale mixture morphologies.
Broader Impacts: This work elucidated the importance of balanced interactions in controlling morphology during coacervation with implications for biological systems that utilize similar physical principles.
Figure: Mixtures of charged polymers create coacervates with unusual and unexpected morphologies.
