Applications of Polycapillary X-ray Optics in Protein Crystallography

Abstract

Using polycapillary X-ray optics, the intensity of the Cu Kα radiation from a Rigaku RU200 rotating-anode generator was increased remarkably compared with Supper double focusing mirrors. A crystal of a double mutant of trichosanthin diffracted beyond 1.9 Å with the application of the polycapillary optics and 2.0 Å resolution data with an overall R_{\rm sym} of 8.4% were collected, while the same crystal only diffracted to about 2.62 Å using the radiation from double focusing mirrors. A small crystal of acidic phospholipase A2 from snake venom diffracted to 2.2 Å employing the polycapillary optics and the overall R_{\rm sym} for the data collected was 8.6%. The same crystal only diffracted to about 2.7 Å using double focusing mirrors. The average intensity of reflections and the signal-to-noise ratio for both of the crystals increased dramatically with the application of the polycapillary X-ray optics. This new kind of X-ray optic has been used to collect good-quality diffraction data for a number of protein crystals.