Reduction of radiation damage and other benefits of short wavelengths for macromolecular crystallography data collection

Circumventing radiation damage remains a major problem for X‐ray macromolecular crystallography. Analysis of diffraction data collected from normal‐sized cryocooled lysozyme crystals shows that the dose required to collect a data set of prescribed resolution and signal‐to‐noise ratio, assuming an ideally efficient detector, decreases with increasing photon energy in the investigated 6.5–33 keV range. For example, the data collection efficiency is increased by a factor of ∼8 from 8 to 33 keV. Monte Carlo simulations on lysozyme crystals in the range 5–80 keV, taking into account electron escape from samples of different size, also show a positive effect of high energy (albeit less pronounced than in experiments), especially for micrometre‐sized samples, and suggest that the optimum energy range is ∼24–41 keV, depending on crystal size. The importance of counting pixel detectors with a good efficiency at high energy is underlined. Macromolecular crystallography beamlines should be modified, or purposely designed, in order to benefit from higher‐energy radiation through reduction of global radiation damage, better data accuracy and extension of phasing by anomalous dispersion.