Polycapillary optic-source combinations for protein crystallography

The work in this paper is a systematic study of the application of collimat ing and slightly focusing polycapillary optics to the X-ray crystallographi c structure determination of egg-white lysozyme using two different sources : a standard rotating anode source and a low-power table-top microfocusing source. For the rotating anode source, a series of measurements comparing d uplicate data sets obtained from the same individual crystal are summarized . Intensity and data quality are discussed for measurements with a pinhole collimator, a collimating polycapillary optic and a focusing polycapillary optic. The collected data were analyzed using conventional analysis softwar e; limitations of the use of conventional analysis software for focused bea ms are discussed. Two data sets were collected using the low-power source a nd collimating optics, and three data sets using a lower-power source and f ocusing optics with three different limiting apertures.