APPLICATIONS OF POLYCAPILLARY X-RAY OPTICS IN PROTEIN CRYSTALLOGRAPHY

Using polycapillary X-ray optics, the intensity of the Cu K alpha radi ation from a Rigaku RU200 rotating-anode generator was increased remar kably compared with Supper double focusing mirrors. A crystal of a dou ble mutant of trichosanthin diffracted beyond 1.9 Angstrom with the ap plication of the polycapillary optics and 2.0 Angstrom resolution data with an overall R-sym of 8.4% were collected, while the same crystal only diffracted to about 2.62 Angstrom using the radiation from double focusing mirrors. A small crystal of acidic phospholipase A2 from sna ke venom diffracted to 2.2 Angstrom employing the polycapillary optics and the overall R-sym for the data collected was 8.6%. The same cryst al only diffracted to about 2.7 Angstrom using double focusing mirrors . The average intensity of reflections and the signal-to-noise ratio f or 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 diMaction data for a number of protein c rystals.