Radiation Damage of Protein Crystal in Various X-ray Energies

The radiation damage of crystals is the most serious problem for obtaining accurate structure in protein crystallography. In order to compare the effect of radiation damage among various X-ray energies, we collected 12 to 15 data sets of tetragonal lysozyme crystals at nine different X-ray energies at 6.5, 7.1, 8.3, 9.9, 12.4, 16.5, 20.0, 24.8 and 33.0 keV, using BL41XU at SPring-8. The processing results of each data set became worse in all nine energies as the measurement progressed. However, it was shown that the change of these parameters depends upon the absorbed dose, expressed in Gray (Gy). Disruption of the disulphide bonds due to the radiation damage was observed on the electron density map even in the highest photon energy (33 keV). Therefore, these results suggest that the radiation damage in such an energy region should be discussed based on the absorbed dose