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A typical process of determining the three-dimensional protein structure
The Phase problem
Apart from growing useful crystals, the most serious bottleneck in determining a new protein structure is to solve the phase problem. The phases can not be determined directly, they have to be deduced indirectly.
If structural homologues are known they can be used to perform molecular replacement.
Other methods are to include heavy atoms, (e.g. Se-Met) and thereafter collect:
High multiplicity single wavelength anomalous dispersions (SAD) data
Multiple wavelength anomalous dispersion (MAD) data or
Use the Multiple isomorphous replacement (MIR) method.
Links on Crystallography, Teaching and learning pages
Crystallography 101
Kevin Cowtan, Univ. York, UK Book of Fourier
Bart Hazes' tutorials University of Alberta
Interactive Tutorial about Diffraction
Merohedral Crystal Twinning Server Todd Yates and Barry Fam
Twin-Refinement with SHELXL Regine Herbst-Irmer
Anomalous scattering
International Union of Crystallography
Tips on crystallization
Ideas on crystallization From Terese Bergfors
Crystallization protocols Johan Zeelen
Crystal growth
If any of these links does not work please let us know by E-mailing norstruct@chem.uit.no
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