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Trehalose prevents myoglobin collapse and preserves its internal mobility
1Department of Physical Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem, Israel.
Biochemistry
|June 10, 1997
Summary
Trehalose preserves internal protein water, preventing heme pocket dehydration and maintaining myoglobin
Area of Science:
- Biophysics
- Protein Dynamics
- Biochemistry
Background:
- Geminate recombination of carbon monoxide (CO) to myoglobin is crucial for understanding protein dynamics and function.
- The role of solvent viscosity and internal protein structure in modulating CO recombination kinetics and spectral properties is not fully understood.
- Trehalose is known for its protective effects against dehydration, but its influence on protein internal dynamics requires further investigation.
Purpose of the Study:
- To quantitatively model the time-dependence of geminate CO recombination in sperm whale myoglobin within a trehalose glass.
- To analyze the associated spectral shifts and understand the factors influencing recombination kinetics.
- To compare the dynamics in trehalose with those in glycerol/water to elucidate the role of internal hydration.
Main Methods:
- Development and application of a quantitative model involving diffusion on a temperature-dependent potential.
- Analysis of time-resolved spectral data for CO recombination in myoglobin reconstituted in trehalose glass.
- Comparison of kinetic and dynamic parameters with previously studied systems (e.g., glycerol/water).
Main Results:
- Inhomogeneous geminate CO recombination was observed, attributed to higher geminate reactivity rather than slower protein relaxation.
- A fraction of hemes exhibited relaxation, leading to an increased recombination barrier.
- The activation energy for conformational diffusion in trehalose was significantly lower than in glycerol/water, and 'protein collapse' was prevented.
Conclusions:
- Trehalose preserves essential internal water molecules in the myoglobin heme pocket, maintaining protein lability and preventing dehydration-induced viscosity.
- This preservation of internal water is postulated to be key to trehalose's protective effects against dehydration.
- The findings highlight the critical role of internal hydration in protein dynamics and function, offering insights into trehalose's protective mechanisms.