Data Collection

James R. Thompson, Ph.D., core director, mounting a frozen protein crystal on the goniometer of an X-ray diffractometer.

James R. Thompson, Ph.D., core director, mounts a frozen protein crystal on the goniometer of a Rigaku MicroMax-007 microfocus X-ray diffractometer.

Core's X-ray detector showing diffraction at approximately 2 angstrom resolution.

An image from the core's X-ray detector showing diffraction at approximately 2 angstrom resolution.

Following crystallization — and crystal selection and preparation — data are collected using X-ray diffraction.

During this process, X-rays are directed toward a single crystal. The rays scatter as they interact with the electron clouds of a macromolecule's atoms, creating a distinct diffraction pattern. Different patterns of spots, called reflections, appear as the crystal is slowly rotated, with the final, combined diffraction pattern of a molecule being a function of all the electron orbitals and their positions in the crystal lattice.

For one sample, data collection normally takes one to two days, though it depends on the crystal's symmetry and the strength of the scattered X-ray radiation, which is stronger from a well-ordered crystal.

The next step after data collection is data analysis.