CRY-PROTECTION OF PROTEIN CRYSTALS IN INTENSE X-RAY-BEAMS

A focused white beam from existing synchrotrons has an intensity comparable with the monochromatic beams available from future undulator beamlines. The beam from station 9.5 on the SRS has therefore been used to examine the radiation damage caused within a protein crystal, cooled to near liquid nitrogen temperature. It was found that observable radiation damage occurred at doses comparable with those which have been observed in cryo-electron microscopy. It would be possible to collect many data sets from the test lysozyme crystal before radiation damage occurred under these conditions. However, it would not be possible to collect a good quality data set from a single protein crystal of a few tens of microns in size, even at liquid nitrogen temperature.