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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Reversible lattice repacking illustrates the temperature dependence of macromolecular interactions
1Institute of Molecular Biology Howard Hughes Medical Institute and Department of Physics, 1229 University of Oregon, Eugene, OR 97403-1229, USA.
Journal of Molecular Biology
|August 24, 2001
Summary
Flash-freezing causes protein crystals to contract due to lattice repacking, altering intermolecular contacts. These cryocooling-induced changes highlight the need for caution when interpreting low-temperature structural data.
Area of Science:
- Structural Biology
- Biophysics
- Crystallography
Background:
- Flash-freezing is standard in macromolecular X-ray crystallography.
- Cryocooling induces significant crystal contraction, impacting structural analysis.
Purpose of the Study:
- To investigate the reversible structural changes in protein crystals upon flash-freezing.
- To understand the impact of cryocooling on intermolecular interactions and lattice packing.
Main Methods:
- X-ray crystallography of Escherichia coli beta-galactosidase.
- Low-temperature density measurements.
- Analysis of intermolecular and intramolecular contact interfaces.
Main Results:
- Flash-freezing causes reversible crystal contraction in beta-galactosidase due to lattice repacking.
- Intermolecular contacts increase by 50% upon cooling, driven by polar side-chains and solvent molecules forming hydrogen-bonded networks.
- Cryocooling perturbs both intramolecular and intermolecular interfaces, with more dramatic effects on intermolecular contacts.
Conclusions:
- Cryocooling-induced lattice repacking significantly alters protein crystal structures.
- Intermolecular interactions observed at low temperatures may not accurately reflect physiological conditions.
- Caution is advised when interpreting protein-protein and protein-nucleic acid interactions from cryocooled structures.
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