On the choice of an optimal wavelength in macromolecular crystallography.

Potential benefits of using short X-ray wavelengths for protein crystal data collection arise from a reduction in absorption errors and a decrease in radiation damage of a sample. On the other hand, at longer wavelengths one may benefit from an increase in scattering efficiency of a crystal and an increase in intensity of an incident beam at a given synchrotron beamline. For small and frozen crystals the negative effects of absorption and radiation damage would be minimized which may shift the balance of interests towards the use of longer wavelengths. Experiments carried out at EMBL beamlines at DESY (Hamburg) show an advantage of using wavelengths longer than 1 A for data collection from crystals of up to 0.5 mm.