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Liquid-solid transition in nuclei of protein crystals
Aleksey Lomakin1, Neer Asherie, George B Benedek
1Department of Physics, Center for Materials Science and Engineering and Material Processing Center, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA.
Summary
Protein crystallization may not start with a crystal nucleus. Instead, disordered protein aggregates form first, transitioning to crystalline structures only after reaching a critical size, challenging traditional nucleation models.
Area of Science:
- Biophysics
- Materials Science
- Crystallography
Background:
- Traditional models assume protein crystallization initiates from a small, ordered crystalline nucleus.
- This paradigm is widely accepted but may not accurately reflect protein crystallization processes.
Purpose of the Study:
- To investigate the initial stages of protein crystallization using numerical simulations.
- To determine if protein clusters can maintain crystalline structures under typical crystallization conditions.
Main Methods:
- Numerical simulations were performed on model proteins with short-range attractive interactions.
- Simulated conditions mimicked those typically used for protein crystal production.
Main Results:
- Small clusters of model proteins could not maintain a crystalline structure under simulated conditions.
- Protein crystal nucleation was identified as an indirect, two-step process.
- A disordered, liquid-like aggregate forms first, enabling nucleation only after reaching a critical size (approx. few hundred particles).
Conclusions:
- Protein crystallization likely involves an initial phase of disordered aggregate formation.
- Nucleation occurs indirectly, requiring the aggregate to exceed a critical size before crystalline structure can emerge.