Image processing and computing in structural biology
Jiang, L.
Citation
Jiang, L. (2009, November 12). Image processing and computing in structural biology. Retrieved from https://hdl.handle.net/1887/14335
Version: Corrected Publisher’s Version
License: Licence agreement concerning inclusion of doctoral thesis in the Institutional Repository of the University of Leiden
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Chapter 7 Conclusions and Perspectives
The research described in this thesis includes new methods for 3DEM single particle reconstruction: new software modules for particle picking and a more efficient CTF correction method. These new methods were used to solve an important biological question: how does the recovery system of heat-shock disrupted 50S ribosomal complexes work? Preliminary research on electron diffraction of nano-crystals allowed unit cell determination and resulted in the EDiff software suite.
Combined with image processing techniques, electron microscopy is powerful enough to investigate the atomic structure of bio-molecules. The potential of electron diffraction is still developing. 3DEM will allow investigations at near-atomic resolution and can become as powerful as the X-ray diffraction method in the foreseeable future. The method of 3DEM still has scope for further research and improvement. For instance for speeding up the Multi-Reference-Alignment process, which is the most time consuming step in the reconstruction. Software packages for iterative refinement and pushing the 3D models to atomic resolution are still in continuous development.
For electron diffraction of 3D protein nano-crystals, lots of work is still needed to determine atomic structures, such as intensity integration, recovering the phase and refinement. The work described in this thesis is only the first step in a series of many that may lead up to a general method for solving structures with diffraction data of 3D protein nano-crystals.
In X-ray crystallography, scientists invest major efforts into growing protein crystals, which in many cases do not grow beyond a size of several micrometers. Solving structures using such protein crystals requires the most advance and expensive third generation synchrotron beam lines. However electron crystallography can deal with even smaller crystals of nanometer size, which are beyond the reach for X-rays, but ideal for electron diffraction.
Chapter 7
Electron crystallography has already been successful for a number of complicated inorganic compounds in material science. Organic and protein crystals are now also being studied by several research groups. There is no theoretical obstacle to solving atomic structures by using electron diffraction. But technical problems do exist, for example, protein crystals suffer from the serious and limiting factor of radiation damage. If these practical problems can be solved, electron diffraction on protein nano-crystals can be of immense importance in the foreseeable future and cryo-EM will be as important as synchrotrons for protein crystallography!
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