Lysozyme crystal growth, as observed by small angle X-ray scattering, proceeds without crystallization intermediates

Area of Science:

• Biophysics
• Crystallography
• Materials Science

Background:

• Protein crystal growth is crucial for structural biology and drug development.
• Understanding lysozyme crystallization kinetics in gels provides insights into protein self-assembly.
• Previous studies showed temperature decrease and crystallizing agent increase promote attractive interactions in lysozyme solutions.

Purpose of the Study:

• To investigate the kinetics of protein crystal growth using a combination of small angle X-ray scattering and gel techniques.
• To determine if oligomers form during the incorporation of lysozyme monomers into growing crystals.
• To examine lysozyme crystallization in NaCl using agarose gels.

Main Methods:

• Utilized small angle X-ray scattering (SAXS) and gel electrophoresis techniques.
• Employed a novel sample holder for inducing supersaturation by decreasing temperature in the presence of salt.
• Studied hen egg white lysozyme at various protein concentrations as a model system.

Main Results:

• Observed similar behavior in NaCl with agarose gels as previously seen with temperature/crystallizing agent changes.
• Found no indication of oligomer formation between solution monomers and the crystal during growth.
• Confirmed that lysozyme remains monomeric in solution under the studied conditions.

Conclusions:

• Lysozyme crystals in NaCl, within agarose gels, grow via the addition of monomeric particles.
• The study supports the hypothesis of monomer addition in lysozyme crystal growth.
• The methods provide a new approach to study protein crystallization kinetics in a controlled environment.