Cloud-point temperature and liquid-liquid phase separation of supersaturated lysozyme solution

Area of Science:

• Biophysics
• Protein Chemistry
• Materials Science

Background:

• Understanding biological macromolecule structure is crucial for drug design and industrial applications.
• Protein crystallization, while advancing, remains an empirical and operator-dependent process.
• Liquid-liquid phase separation is a key phenomenon in protein solution behavior.

Purpose of the Study:

• To investigate liquid-liquid phase separation in supersaturated lysozyme solutions using microcalorimetry.
• To determine the effects of ionic strength and glycerol on the cloud-point temperature of lysozyme solutions.
• To provide a more scientific approach to understanding protein crystallization parameters.

Main Methods:

• Utilized microcalorimetry to measure cloud-point temperature (T(cloud)).
• Investigated supersaturated lysozyme solutions.
• Systematically varied sodium chloride concentrations to study ionic strength effects.
• Added glycerol as an additive to assess its impact on solubility and cloud-point temperature.

Main Results:

• Cloud-point temperature of lysozyme solutions increased monotonically with increasing sodium chloride concentration.
• Glycerol addition increased lysozyme solubility.
• Glycerol addition decreased the cloud-point temperature of lysozyme solutions.

Conclusions:

• Microcalorimetry provides a quantitative method to study protein phase separation.
• Ionic strength and additives like glycerol significantly influence lysozyme solution behavior and crystallization conditions.
• Findings contribute to a more predictable and less empirical approach to protein crystallization.