title: Primary radiation damage of protein crystals by an intense synchrotron X-ray beam.
abstract: X-ray radiation damage of a lysozyme single crystal by an intense monochromatic beam from a third-generation radiation source at the Advanced Photon Source has been studied. The results show that primary radiation damage is linearly dependent on the X-ray dose even when the crystal is at cryogenic temperatures. The existence of an upper limit for the primary radiation damage was observed. Above the threshold of approximately 1 x 10(7) Gy, excessive damage of the crystal develops which is interpreted as the onset of secondary and/or tertiary radiation damage. This upper limit of X-ray dose is compared with Henderson's limit [Henderson (1990). Proc. R. Soc. London, B241, 6-8], and its implication for the amount of useful X-ray diffraction data that can be obtained for crystals of a given scattering power is also discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA. t-teng@uchicago.edu
authors.forename: T Y
authors.initials: TY
authors.lastname: Teng
authors.forename: K
authors.initials: K
authors.lastname: Moffat