Crystallization is the most important — and most difficult — part of crystallography. Single near-perfect crystals are required for X-ray diffraction and structure determination, but obtaining suitable and reproducible crystals is neither easy nor predictable.

Crystals generated from pure macromolecular samples are needed because X-ray diffraction from a single molecule is too weak to measure. The signal is greatly magnified when highly ordered 3D arrays of electrons are scattering together, as from a macromolecular crystal. The protein crystals made within the Structural Biology Facility contain several billion molecules at very high molarity.

Considerable effort has been devoted to crystallization theory and practice, yet the phenomenon remains poorly understood and empiric. Success is somewhat a result of the investigator's skill and experience, but mostly stems from motivation, patience and a bit of luck. Beginners should not be intimidated by crystallization, as they are about as likely as experts to generate exciting results.

The crystallization process can take from a single day to several weeks — and sometimes longer. To assist with the tasks involved in crystallization, the Structural Biology Facility features robotic crystallization, dedicated crystal storage at various temperatures and automated crystal viewing.

Once crystals have been formed, selected and prepared, X-ray diffraction data can be collected.