Accurate and highly complete synchrotron protein crystal Laue diffraction data using the ESRF CCD and the Daresbury Laue software

Developments in electronic area detectors such as CCDs and image plates have transformed the capability of the synchrotron Laue protein crystallography technique compared with film. The rapid readout of CCDs makes practical the use of rather fine angular interval settings of the crystal between each Laue exposure and a large overall angle coverage. The use of the ESRF CCD (image intensifier type) presented here in the Laue data collection on ESRF ID09 (the `Laue beamline') from a single crystal of the 34 kDa wild-type hydroxymethylbilane synthase (HMBS), space group P2<sub>1</sub>2<sub>1</sub>2 a = 88.06, b = 75.73, c = 50.35 Å, yielded 47 Laue exposures in 2.5° angle intervals from a single crystal. The data processed by the Daresbury Laue software is highly complete (∞–2d<sub>min</sub> = 77.5%; 2d<sub>min</sub>–d<sub>min</sub>= 91.7%) to 2.3 Å with high redundancy (11.2). Comparison with calculated structure factors and careful analysis of the Laue geometry shows that between ∞ and 5d<sub>min</sub> better completeness still should be possible, which can ideally be realized from CCD detector dynamic range hardware improvements and/or software algorithms to integrate saturated spot profiles. Prospects for Laue diffraction data collection using yet faster detectors such as the `pixel detector' to study irreversible catalytic structural processes in a crystal, the most challenging of all time-resolved experiments, are bright.