USE OF MULTILAYER MONOCHROMATORS FOR MACROMOLECULAR CRYSTALLOGRAPHY

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Crystallographic studies of weakly-diffracting biological samples using bending-magnet beamlines at the NSLS frequently are limited by the low intensity of the focussed, monochromatic X-ray beam striking the sample. For example, direct comparison of beamlines X4A, X8C X I 2B, and X I 2C (bending magnets) with beamline X25 (wiggler) demonstrated that the bending-magnet beamlines do not offer sufficient flux for studies of some of the most interesting and difficult crystallographic problems - large macromolecular complexes - at their highest possible resolution limits. With the growing number of protein crystallography laboratories in both academe and industry, wiggler beamlines suitable for routine x-ray diffraction data collection from the most weakly diffracting specimens are now heavily over- subscribed. Acknowledging the difficulty in simply building more wiggler beamlines, one would like to find an alternative means to provide dramatically more x-ray flux at the NSLS so that one ca n approach these difficult problems.