DALI
Extending the capacity and capability for neutron macromolecular crystallography
Guide hall n°1, cold guide H141 |
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Data Collection Method | |
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Quasi-Laue | Neutron Velocity Selector |
Typical neutron λ | 3.35 to 3.70 Å (with NVS@25K rpm) |
Collimation | |
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Pinholes | 0.5 to 2.9 mm |
Flux at specimen | |
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(λ-centre = 3.53 Å; δλ/λ ~10%) | ~1 x 108 n cm-2 s-1 |
Detector | |
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Cylindrical drum with internal neutron-sensitive image plates and read/erase system | |
Neutron image plate | Gd2O3 doped BaF(Br.I):Eu2+ |
Radius | 160 mm |
Length | 400 mm |
Active area | 1000 x 400 mm2 |
Pixel size | 100, 200, 400 µm2 |
Sample environment |
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(1) Ambient or (2) Oxford Cryosystems 'COBRA' cryostream (down to 80K) |
A huge advance for high-resolution studies of large proteins
In October 2025, a completely new neutron-sensitive cylindrical image plate detector was built and installed on DALI. Neutron diffraction tests and analyses were performed using crystals of proteins covering a wide range of molecular weights, from the very small (6 kDa) to the very large (271 kDa). The results show that the LADI-III and DALI macromolecular crystallography diffractometers are highly complementary.
LADI-III delivers higher quality diffraction data for small to medium-sized proteins (5-70 kDa) and DALI, with its new detector and narrow bandwidth velocity selector, now delivers diffraction data of higher quality for large proteins (70-150 kDa). In addition, the tests indicate that DALI can even be used to study very large proteins (>150 kDa) that were previously out of range. This represents a step change in capabilities for neutron protein crystallography research and further cements the ILL’s position as world-leading in the field.
Below shows a 16-hour exposure from a crystal of 105 kDa protein (LecA/PheGal complex, unit-cell, a = 74, b = 111, c = 113 Å / P212121). Complete data set collected to 2.0 Å resolution. [LecA protein is a virulence factor of the pathogenic bacteria Pseudomonas aeruginosa. Specific ligands - molecules binding to specific sites of the protein to form molecular complexes – can counteract P. aeruginosa infections if they block specific protein sites involved in the process.]
