Journal of Applied Crystallography

Volume 38, Part 3 (June 2005)

research papers

J. Appl. Cryst. (2005). 38, 512-519 [ doi:10.1107/S0021889805009234 ]

Advances in digital topography for characterizing imperfections in protein crystals

J. J. Lovelace, C. R. Murphy, H. D. Bellamy, K. Brister, R. Pahl and G. E. O. Borgstahl

Abstract: A system which joins digital topography with fine [varphi] -sliced reflection profiling has been developed and applied to cryocrystallography. In this demonstration, fifteen fine -sliced reflection profiles with corresponding topographic sequences are evaluated: twelve reflections from a crystal at cryogenic temperatures and three reflections from a room-temperature crystal. The digitally collected data show results comparable with film, albeit at a lower resolution, but are acquired at a substantially higher rate. Additionally, anti-blooming circuitry in the CCD was tested and shown to provide useful data even when pixels were overloaded.

Keywords: topography; mosaicity; crystal quality; cryocrystallography; macromolecular crystallography; reflection profiles; cryocooling.