CONVERGENT BEAM MACROMOLECULAR CRYSTALLOGRAPHY USING POLYCAPILLARY X-RAY OPTICS. J. B. Ullrich^#, S. M. Owens^*, Q.-F. Xiao^#, I. Yu. Ponomarev^#, D. Carter⁺, R. C. Sisk⁺, and W. M. Gibson^*, ^*Center for X-ray Optics, University at Albany, Albany, NY 12222 ^#X-Ray Optical Systems, 90 Fuller Rd., Albany, NY 12205, ⁺Laboratory for Structural Biology, NASA Marshall Space Flight Center, Huntsville, AL 35812

The viability of macromolecular crystallography is dependent on the ability to view large volumes of reciprocal space during a single x-ray exposure. The most popular methods used to do this are precession, rotation (or oscillation), and Laue photography, but a convergent beam can, in principle, achieve the same result. Although the convergent beam technique has been considered as an alternative to the oscillation method (Wyckoff and Agard, The Rotation Method in Crystallography), it has not been generally adopted by the crystallographic community. Polycapillary x-ray optics can collect x-rays over large solid angles and re-focus the x-ray beam to < 1 mm spots, yielding significant intensity gains at the crystal, and simultaneously exposing large volumes of reciprocal space without having to oscillate the crystal. The ability to generate convergent beams with existing sources, coupled with the potentially large intensity gains, warrants serious re-examination of the convergent beam method. This technique could be particularly important for the case of small crystals, since focal spot sizes of 20 - 40 microns are obtainable with strong focusing. We have conducted a study of convergent beam crystallography using polycapillary x-ray optics and its effect on data collection and quality. The results of this study, including the potential for significantly faster data collection with smaller crystals, will be presented.