Dissolution rate of hen egg-white lysozyme crystal under microgravity

Area of Science:

• Biophysics
• Materials Science
• Space Science

Background:

• Microgravity has shown potential for improving protein crystallization, with approximately 20% of proteins crystallizing better in space.
• However, a lack of understanding of the underlying mechanisms hinders further development of space-based protein crystallization techniques.
• Observing elementary stages of crystallization is crucial for process optimization.

Purpose of the Study:

• To investigate the mechanism of protein crystallization by measuring the dissolution rate of a single hen egg-white lysozyme crystal.
• To compare crystal dissolution rates under microgravity conditions with those on Earth.
• To identify factors influencing protein crystal growth and dissolution.

Main Methods:

• Experiments were conducted during the STS-84 space shuttle mission using a vapor diffusion apparatus.
• Single hen egg-white lysozyme crystals were dissolved in unsaturated NaCl solutions under microgravity.
• Control experiments were performed on Earth, measuring solution concentrations at regular intervals during crystal dissolution.

Main Results:

• The study measured the dissolution rate of hen egg-white lysozyme crystals under microgravity and on Earth.
• Contrary to expectations, the dissolution rate on Earth was not found to be larger than under microgravity.
• Marangoni convection effects within the experimental apparatus are proposed as a potential explanation for the observed results.

Conclusions:

• The effectiveness of microgravity in protein crystallization is confirmed, but the precise mechanisms require further investigation.
• Observed dissolution rates challenge initial hypotheses based on convection differences between Earth and microgravity.
• Marangoni convection may play a significant role in protein crystallization experiments conducted in space, influencing dissolution rates.