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Projekt Druckansicht

Liquid-liquid phase separation and crystallization in protein solutions induced by multivalent metal ions

Fachliche Zuordnung Statistische Physik, Nichtlineare Dynamik, Komplexe Systeme, Weiche und fluide Materie, Biologische Physik
Förderung Förderung von 2011 bis 2016
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 197073534
 
Erstellungsjahr 2016

Zusammenfassung der Projektergebnisse

We have performed a systematic and successful research on tuning protein interactions and phase behavior in solution using charges, in particularly the metastable liquid-liquid phase separation and its role on protein crystallization. Small angle X-ray or neutron scattering together with the liquid state theoretical approach were employed to characterize the effective interactions in protein solutions. Interactions as a function of protein concentration, ionic strength, and the nature of salt can be readily characterized using a suitable model potential. Using trivalent metal ions, for the first time, we discovered the reentrant condensation in protein solutions, which might be a rather universal behavior for acidic proteins. An analytical model has been developed for charge regulation by taking into account ion condensation, metal ion hydrolysis and interaction with charged amino acid side chains on the protein surface. Within the condensed regime, protein solutions can undergo metastable liquid-liquid phase separation, clustering, and protein crystallization, which further demonstrate the tunable interactions in protein solutions using charge. This rich phase behavior can be rationalized using an ion-activated patchy colloid model. Furthermore, the application of the framework on protein crystallization have shown that the tunable phase behavior can be used to optimize growth conditions for high quality protein single crystals, which can potentially apply to all acidic proteins. Systematic studies on the nucleation and crystal growth kinetics under various conditions provide deep insight of the classical and nonclassical pathways for protein crystallization, such as a two-step crystallization via a metastable LLPS. Recent progress using real-time SAXS and optical microscopy has revealed unique structural features and the growth kinetics of the nonclassical nucleation mechanism. The effect of tunable phase behavior in protein solutions using metal ions has potentially far reaching consequences for a broad range of issues from protein crystallization to proteincondensation related diseases and the structural organization in living cells.

Projektbezogene Publikationen (Auswahl)

 
 

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