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Specific protein dynamics near the solvent glass transition assayed by radiation-induced structural changes
M Weik1, R B Ravelli, I Silman
1Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands. weik@ibs.fr
Protein Science : a Publication of the Protein Society
|September 22, 2001
Summary
Protein X-ray crystallography reveals that solvent mobility above its glass transition temperature significantly increases enzyme radiation damage and causes atomic-level inactivation. This highlights the crucial role of protein and solvent dynamics in macromolecular radiation effects.
Area of Science:
- Structural biology
- Biophysics
- Crystallography
Background:
- The dynamical coupling between proteins and their solvent environment is poorly understood.
- X-ray irradiation can induce structural changes and damage in proteins.
- The glass transition of crystalline solvent affects molecular dynamics.
Purpose of the Study:
- To investigate structural alterations in acetylcholinesterase upon X-ray irradiation at different temperatures relative to solvent glass transition.
- To elucidate the role of protein-solvent dynamics in X-ray-induced radiation damage and enzyme inactivation.
Main Methods:
- Temperature-dependent protein crystallography of acetylcholinesterase.
- X-ray irradiation experiments conducted below (100 K) and above (155 K) the solvent's glass transition temperature.
- Analysis of structural changes, unit cell volume, and active site conformation.
Main Results:
- Increased radiation damage observed at 155 K compared to 100 K, affecting disulfide bonds, cysteine, and methionine residues.
- Non-linear unit cell volume increase at 155 K, attributed to enhanced solvent mobility.
- Conformational changes in the catalytic triad at 155 K, leading to radiation-induced enzyme inactivation at the atomic level.
Conclusions:
- Protein flexibility increases above the solvent's glass transition temperature, enabling adaptation to irradiation-induced changes.
- Solvent dynamics critically influence protein flexibility and susceptibility to radiation damage.
- Protein and solvent dynamics are vital for understanding radiation damage in biological macromolecules and can be exploited to study protein flexibility.