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Myoglobin solvent structure at different temperatures
B V Daniels1, B P Schoenborn, Z R Korszun
1Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Basic Life Sciences
|January 1, 1996
Summary
Neutron diffraction reveals that water molecules around myoglobin crystals form distinct hydration shells, not disordered solvent. These ordered shells expand with increasing temperature, indicating a phase transition around 180K.
Area of Science:
- Biophysics
- Structural Biology
- Crystallography
Background:
- Understanding protein hydration is crucial for biological function.
- Previous studies suggested disordered solvent around protein crystals.
- Myoglobin serves as a model protein for studying hydration dynamics.
Purpose of the Study:
- To investigate the structural organization of water molecules surrounding myoglobin crystals.
- To determine if the solvent exhibits ordered hydration shells or disordered structure.
- To analyze the effect of temperature on protein hydration structure.
Main Methods:
- Neutron diffraction data collection at multiple temperatures (80K, 130K, 180K, 240K).
- Analysis of low-resolution data using Relative Wilson Statistics.
- Quantification of solvent structure using the liquidity factor (Bsn) as a function of distance from the protein surface.
Main Results:
- Evidence of a phase transition in the solvent structure around 180K.
- Identification of two distinct, well-defined hydration shells surrounding the myoglobin crystals.
- Observation that both hydration shells expand with increasing temperature.
- The liquidity factor (Bsn) shows minima at approximately 2.35Å and 3.85Å from the protein surface.
Conclusions:
- The solvent structure around myoglobin crystals is not disordered but organized into specific hydration shells.
- Temperature significantly influences the expansion and structure of these hydration shells.
- A phase transition occurs around 180K, affecting the solvent's structural organization.