Lysozyme crystal growth kinetics monitored using a Mach-Zehnder interferometer

Area of Science:

• Crystallography
• Biophysics
• Optical Physics

Background:

• Protein crystal growth is vital for structural biology and drug discovery.
• Monitoring diffusion kinetics is essential for optimizing crystal quality.
• Microgravity environments offer unique advantages for protein crystallization.

Purpose of the Study:

• To develop and validate a Mach-Zehnder interferometer for real-time monitoring of protein crystal growth kinetics.
• To assess the feasibility of using this device in microgravity conditions, such as on the International Space Station.
• To correlate optical measurements with visual observations of crystal growth.

Main Methods:

• A Mach-Zehnder interferometer was designed and implemented.
• The interferometer was coupled with a protein dialysis reactor and an engineering model of the European Space Agency's Advanced Protein Crystallization Facility (APCF).
• Ground-based experiments were conducted using chicken egg-white lysozyme as a model system, monitoring concentration changes via refractive index measurements.

Main Results:

• The interferometer successfully monitored the kinetics of the diffusion process during lysozyme crystallization.
• Refractive index changes directly correlated with solution concentration variations over time.
• Direct correlation was established between optical measurements and visual monitoring of crystal growth.

Conclusions:

• The developed Mach-Zehnder interferometer is a viable tool for in-situ monitoring of protein crystal growth kinetics.
• The system is suitable for microgravity applications, enhancing the study of diffusion-controlled crystallization processes.
• This technology can significantly contribute to improving protein crystallization strategies for structural and pharmaceutical research.