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Electron diffraction of wet proteins: catalase
Science (New York, N.Y.)
|July 21, 1972
Summary
High-resolution electron diffraction was achieved from wet catalase microcrystals, revealing 3500 reflections. Diffraction ceased below 90% relative humidity, highlighting the critical role of hydration in preserving crystal structure for imaging.
Area of Science:
- Biophysics
- Crystallography
- Biochemistry
Background:
- Catalase is an essential enzyme involved in cellular defense against oxidative stress.
- Microcrystal electron diffraction (MED) is a powerful technique for determining the structure of biological macromolecules.
- Maintaining sample hydration is crucial for preserving the structural integrity of biological samples during electron microscopy.
Purpose of the Study:
- To obtain high-resolution electron diffraction data from microcrystals of catalase.
- To investigate the effect of hydration on the diffraction quality of catalase microcrystals.
Main Methods:
- Microcrystals of catalase were prepared and maintained under controlled humidity conditions.
- Electron diffraction patterns were collected using a transmission electron microscope.
- Diffraction data was analyzed to determine the resolution and number of reflections.
Main Results:
- Electron diffraction patterns with 3500 reflections extending to 2 angstrom resolution were obtained from hydrated catalase microcrystals.
- No diffraction was observed when the water vapor pressure was reduced below 90% of the equilibrium value, indicating loss of structural order.
Conclusions:
- High-resolution structural analysis of catalase is feasible using electron diffraction.
- Sufficient hydration is essential for maintaining the crystalline order of catalase microcrystals for diffraction studies.
- These findings underscore the importance of environmental control in cryo-EM and MED studies of biological molecules.