Determination of macromolecular structures from anomalous diffraction of synchrotron radiation.
Resonance between beams of x-ray waves and electronic transitions from bound atomic orbitals leads to a phenomenon known as anomalous scattering. This effect can be exploited in x-ray crystallographic studies on biological macromolecules by making diffraction measurements at selected wavelengths associated with a particular resonant transition. In this manner the problem of determining the three-dimensional structure of thousands of atoms is reduced to that of initially solving for a few anomalous scattering centers that can then be used as a reference for developing the entire structure. This method of multiwavelength anomalous diffraction has now been applied in a number of structure determinations. Optimal experiments require appropriate synchrotron instrumentation, careful experimental design, and sophisticated analytical procedures. There are rich opportunities for future applications.
Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.
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Hendrickson
D003461:Crystallography / Q000379:methods*; D008958:Models, Molecular; D015394:Molecular Structure; D010315:Particle Accelerators; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000295:instrumentation*