Charge-controlled metastable liquid-liquid phase separation in protein solutions as a universal pathway towards crystallization

Research output: Contribution to journalArticle


We demonstrate that a metastable liquid-liquid phase separation (LLPS) in protein aqueous solutions can be induced by multivalent metal ions at room temperature. We determine the salt and protein partitioning in the two coexisting phases. The structure factor obtained by small angle X-ray scattering provides direct evidence for a short-ranged attraction, which leads to the metastability of the LLPS. An extended phase diagram with three control parameters (temperature, protein and salt concentration) provides a conclusive physical picture consistent with a criterion for the second virial coefficient. The presented isothermal control mechanism of the phase behavior opens new perspectives for the understanding of controlled phase behavior in nature. Furthermore, we discuss the application of this framework in predicting and optimizing conditions for protein crystallization.


  • Fajun Zhang
  • Roland Roth
  • Marcell Wolf
  • Felix Roosen-Runge
  • Maximilian W.A. Skoda
  • Robert M.J. Jacobs
  • Michael Stzucki
  • Frank Schreiber
External organisations
  • University of Tübingen
  • Friedrich-Alexander University Erlangen-Nürnberg
  • Rutherford Appleton Laboratory
  • University of Oxford
  • European Synchrotron Radiation Facility
Original languageEnglish
Pages (from-to)1313-1316
Number of pages4
JournalSoft Matter
Issue number5
Publication statusPublished - 2012 Feb 7
Publication categoryResearch
Externally publishedYes