In order to solve a protein structure a crystal of a certain quality is required. Data collection is performed on a synchrotron, e.g. in Lund(Sweden) or Grenoble(France). Atoms in a crystal are arranged in planes, each of which reflects photons like a simple plane mirror. The reflected waves from parallel planes can interfere with each other constructively or destructively thereby producing a distinct diffraction pattern.
Left: Mounted crystal in cryo-loop. Right: Detector with diffraction pattern from a protein.
The X-ray structure makes it possible to explain a lot of the biochemical and biophysical properties of proteins that are otherwise unrevealed. This could for example be an explanation of thermo stability, acid resistance, enzymatic activity etc. the vast majority of enzymatic mechanisms are derived from protein structures, and a good structure is a requirement for structure based drug design.
The crystal structure of tobacco peroxidase determined at 2.0 Å resolution.