Ultrahigh resolution protein crystallography: Concanavalin A to 0.94 A and beyond
- Department of Chemistry, University of Manchester, Manchester M13 9PL (England)
- The Weizmann Institute (Israel)
Many years ago the idea of collecting voluminous quantities of weak reflection intensities from a protein crystal, at high resolution, was a particular challenge [J.R. Helliwell (1979) Daresbury Study Weekend DL/SCI R13, pp. 1{endash}6]. The combination of insertion devices with very high x-ray fluxes at short x-ray wavelengths, sensitive CCD detectors, and freezing of crystals have provided the means to certainly match those best hopes. So much so that the data can best be described as ultrahigh resolution, at least as evidenced in our studies of the 25000 molecular weight plant protein concanavalin A. (The intrinsic property of this protein is to bind sugar molecules; it is implicated in cell-to-cell recognition processes and is widely used as a laboratory diagnostic tool.) At CHESS we have used a 0.9 A wavelength beam on station A1, fed by a 24 pole multipole wiggler. Both an imaging plate system and the Princeton 1k CCD detector [M. Tate {ital et} {ital al}., J. Appl. Cryst. {bold 28}, 196 (1995)] have been used on this experimental setup to collect diffraction data sets from frozen concanavalin A crystals (saccharide-free crystal form). The rapid readout of the CCD was most convenient compared with the image plate and its associated scanning and erasing. Moreover the data processing results towards the edges of the detectors, 0.98 A, show that the CCD is much better than the image plate at recording these weaker data (Rmerge(I) 13{percent} versus 44{percent}, respectively). The poor performance of the image plate with weak signals has of course been documented by the Daresbury detector group [R. Lewis, J. Synchrotron Radiation {bold 1}, 43 (1994)]. However, the aperture of the CCD used was limiting here. Very recently, in another run at CHESS with the CCD on A1, we have been able to record diffraction data to 0.94 A by further offsetting the detector. We again found that the reflections are still strong at the edge. (Abstract Truncated)
- OSTI ID:
- 390558
- Report Number(s):
- CONF-9510119-; ISSN 0034-6748; TRN: 96:027997
- Journal Information:
- Review of Scientific Instruments, Vol. 67, Issue 9; Conference: SRI `95: synchrotron radiation instrumentation symposium and the 7. users meeting for the advanced photon source (APS), Argonne, IL (United States), 16-20 Oct 1995; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
A new macromolecular crystallography Station (9. 5) on the SRS wiggler beam line for very rapid Laue and rapidly tunable monochromatic measurements: Commissioning and first results
POWTEX visits POWGEN