Pattern formation and coarsening during metastable phase separation in lysozyme solutions.

Area of Science:

• Biophysics
• Materials Science
• Crystallography

Background:

• Protein crystallization is crucial for structural determination using X-ray analysis.
• Phase transformations in protein solutions can lead to complex structures.
• Understanding these transformations is key to optimizing crystal growth.

Purpose of the Study:

• To investigate the structural changes during phase transformations of lysozyme solutions.
• To explore the formation and evolution of intermediate phases like droplets and sponges.
• To determine the factors influencing the transition from sponge structures to crystals.

Main Methods:

• Observation of lysozyme solutions undergoing phase transformations.
• Monitoring the formation, coalescence, and merging of protein-rich droplets.
• Analysis of the transition from a spongelike structure to crystalline forms.
• Varying salt concentration to influence droplet coalescence and crystal nucleation timescales.

Main Results:

• Observed initial separation of protein-rich liquid droplets.
• Documented droplet coalescence into an interconnected spongelike structure over an hour.
• Confirmed the final transformation of the sponge phase into protein crystals.
• Demonstrated that salt concentration affects the relative timescales of coalescence and nucleation.

Conclusions:

• The formation of the sponge phase is dependent on the balance between droplet coalescence and crystal nucleation rates.
• Control over salt concentration allows manipulation of these intermediate phases.
• These findings have implications for developing improved methods for protein crystal production for X-ray crystallography.