The emergence of the synchrotron Laue method for rapid data collection from protein crystals

Abstract

Synchrotron X-radiation (SR) is intense, polychromatic and collimated. It is widely exploited, in macromolecular crystallography, particularly using a monochromatized short wavelength beam. The spectral curve of SR, however, ideally lends itself to use of Laue geometry, i. e. the original diffraction experimental arrangement based on a stationary crystal and a polychromatic X-ray beam. Rapid exposure times and time-resolved crystallography studies, e. g. of enzymes, are now possible. Historical objections to the use of Laue diffraction data, particularly the multiplicity distribution, have been found not to be as limiting as once thought. The credentials of the Laue method have been established through a variety of Laue crystal structure analyses, involving photographic film as detector. Recently a three-dimensional arrangement of films, known as a toast-rack, has been used to alleviate problems with spatially overlapping spots. This paper provides a review of these results and then reports several developments. In particular, one of the first Laue analyses using an image plate as detector, namely of a cobalt substituted concanavalin A crystal, is discussed. Recent experimental developments, also at the Daresbury synchrotron, are then described. First, a large toast-rack has been used to record Laue data from a protein crystal. Secondly, a transmission X-ray mirror has been constructed from thin mylar (1.5 μm) and used to provide a λ max filter instead of using aluminium foils. Thirdly, since the Laue method suffers from poor sampling of the low resolution data, a new method (known as LOT) has been introduced.

Recording Diffraction Data for Structure Determination for Very Small Crystals

“…The distribution of incident intensity with respect to wavelength is determined by the synchrotron source characteristics, and any optical elements in the beamline, but it can be modified by the insertion of absorbers, for example A1 or Cu foils (see, for example, Harding, 1991). Alternatively, a long-wavelength cut-off can be achieved by glancing-angle reflection from a mylar film (Cassetta et al, 1993). The complete removal of radiation with wavelengths > 1.2-1.4/~ can greatly reduce radiation damage in sensitive crystals, e.g.…”

Trends and Challenges in Experimental Macromolecular Crystallography

“…The application of this to study the laser light stimulated photodissociation of carbon monoxide bound to the haem in myoglobin is thus underway (Bourgeois et al 1996), essentially probing then the nanosecond behaviour of this protein structure complex. The emergence of the synchrotron Laue method for rapid data collection from protein crystals (reviewed in Cassetta et al (1993)) has stimulated a strong interest to study enzyme reactions in a crystal in real time, with examples including the protein p2i in guanosine triphosphate (GTP) hydrolysis (Schlichting et al 1990;Scheidig et al 1994), trypsin (Singer et al 1993) and isocitrate dehydrogenase (Bolduc et al 1995) as well as photostimulable systems like CO myoglobin (Bourgeois et al 1996).…”