X-ray crystallography relies on the analysis of diffraction patterns produced as X-ray beams get scattered by the electrons of a crystallized molecule. Position and intensity of the diffraction spots reflect the specific spatial arrangement of atoms in the crystal. Diffraction patterns can be processed and analyzed to generate an electron density map upon which an atomic model of the biomolecule of interest can be built.
Is X-ray crystallography the right technique for your project?
- Yes, if your project requires very precise structural information. Structure of biomolecules can be solved with very high resolution (sub-Å) by X-ray crystallography. It is the method of choice to determine for example the precise arrangement of amino acid side chains in the active site of an enzyme.
- Yes, if a closely related structure is already solved and deposited in the Protein Data Bank. Generation of an electron density map requires information about the phase of the diffraction. Recovering information about lost phases can be done relatively easily by molecular replacement if a closely related structure is available. Otherwise, the phasing process can be lengthy and challenging.
X-ray crystallography instrumentation available on campus
The X-ray Crystallography Facility at ISU is equipped with a mosquito® instrument for commercial crystallization screens, as well as a dragonfly® system for custom screens. A CrysCam Digital microscope is available for semi-automated imaging of crystallization drops. The facility also equipped with home-source X-ray diffractometer (Rigaku Micro Max 007).