Beamline ID23 is part of the Macromolecular Crystallography Group which supports the study and structure determination of biological macromolecules. The beamline is composed of two independent end-stations. ID23-1 is a fully tunable beamline capable of MAD measurements from 6 to 20 keV energy (2.07 Å to 0.62 Å). The second station, ID23-2, is fixed energy (14.20 keV, 0.873 Å) and is dedicated to perform experiments with very small protein crystals and serial crystallography. The optical design of ID23-2 makes use of a horizontally diffracting Si (111) monochromator and Pt coated mirrors in a Kirkpatrick-Baez (KB) geometry as the focusing system.
The X-ray sources for the two stations are canted (separated by 1.5mrad of angle) undulators mounted on a special carriage on the storage ring. The ID23-1 undulator is a U35 (allowing tuning of the energy across harmonics) and for ID23-2 a U20.2 is used which is a pseudo-monochromatic source with a single first harmonic at 14.2keV.
EMBL have provided a scientist position to operate the ID23-2 beamline.
Protein crystal samples are becoming ever smaller, with today's samples typically around 50 to 100 microns in size. With the development of third generation synchrotron radiation sources, it is now possible to have access to a focused and very intense hard X-ray beam in the µm-range. ID23-2, which produces a focused beam of less than 10 µm in diameter (FWHM) to allow to nable the study of microcrystals as well as facilitate serial crystallographic experiments.
Small is beautiful: protein micro-crystallography ; Cusack S, Belrhali H, Bram A, et al. NATURE STRUCTURAL BIOLOGY 5: 634-637 Suppl. S AUG 1998
Protein microcrystals and the design of a microdiffractometer: current experience and plans at EMBL and ESRF/ID13 ; Perrakis A, Cipriani F, Castagna JC, et al. ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY 55: 1765-1770 Part 10 OCT 1999
The ID23-2 structural biology microfocus beamline at the ESRF, David Flot et al., J Synchrotron Radiat. 2010 January 1; 17(Pt 1): 107–118.
Microfocus beam, fixed wavelength rapid data collection and SAD/MIR.
When coming on ID23-2, as a user, you will have to deal with a small and intense beam. Keeping a a 2000 µm3 (about 20 x 10 x 10 µm3) crystal in a 10 µm diameter beam needs good beam stability AND accurate crystal centring.
To maximise success rates and data quality, we reocmmend using the minimum amount of cryoprotection possible (or no cryoprotectant at all). This can be important for reducing background as well as optical centering of crystals, although X-ray centering is also available on the beamline.
In normal operating conditions, small beam drifts (variations in position of less than 10 µm in both vertically and horizontally directions) have been regularly observed over a period of 12 hours. Such variations are expected and are mainly driven by experimental hutch temperature variations. This kind of small drift does not affect data quality as a typical data collection is less than 15 mn. In the past, in certain conditions, larger beam movements (in the range of 50 µm over half an hour) have been observed (mainly after a "Beam Realign" procedure) but should not anymore exist.
The possibility of beam drift makes regular beam position checks necessary. This can be done either with a pop-up scintillator or a scintillator mounted on the Phi axis as a sample. The second option gives a more accurate result as it possible to move the scintillator to the camera focus.
A major upgrade to the optics, diffractometer and sample changer are planned. Works will begin in October of 2016 and end in April 2017.
Tel: +33 (0)4 76 88 +ext
ID23-2 Control Cabin: 25 90
Scientist in charge: Max NANAO, ext 4087