Sam Becker using a Rigaku Desktop Minstrel UV, a robotic imaging system.

Sam Becker, a gifted student from Mayo High School in Rochester, Minn., reviews protein crystallization trials using a Rigaku Desktop Minstrel UV, a robotic imaging system.

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 a highly ordered, 3D array of electrons are scattering together, as from a macromolecular crystal. The protein crystals made within the Structural Biology Laboratory 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're about as likely as experts to generate exciting results.

Wasantha K. Runatunga, Ph.D., looking at crystals using a stereomicroscope.

After much optimization of crystallization conditions, research fellow Wasantha K. Runatunga, Ph.D., seeks the perfect protein crystal for diffraction data using a Leica MZ12.5 stereomicroscope.

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 Lab features robotic crystallization, dedicated crystal storage at various temperatures and automated crystal viewing. Learn more about the lab's equipment and instrumentation.

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