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| Hauptseite > Workflowsammlungen > Öffentliche Einträge > New sample environment options at the neutron diffractometer “BioDiff” |
| Hauptseite > Workflowsammlungen > Öffentliche Einträge > New sample environment options at the neutron diffractometer “BioDiff” |
| Conference Presentation (Other) | FZJ-2013-05554 |
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2013
Please use a persistent id in citations: http://hdl.handle.net/2128/5582
Abstract: The neutron diffractometer BioDiff is a joint project of the Forschungszentrum Jülich (FZJ/JCNS) and the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II). BioDiff is especially designed to collect data from crystals with large unit cells. The main field of application is the structure analysis of proteins, especially the determination of hydrogen atom positions. Typical scientific questions addressed are the determination of protonation states of amino acid side chains and the characterization of the hydrogen bonding network between the protein and an inhibitor or substrate. The orientation of water molecules in the active centre of the protein can also be determined. To first solve the structure of the protein using x-rays is a prerequisite for a successful experiment at BioDiff because we use the x-ray structure to solve the phase problem of crystallography. In some cases it is desirable to record the neutron data set at the same temperature as the x-ray data set. Especially this enables a joint neutron/x-ray refinement. Since the x-ray data at synchrotrons are often measured at cryogenic temperatures of 100 K we integrated a standard Oxford Cryosystems “Cryostream 700 Plus” as a new sample environment option to the instrument BioDiff (see Fig. 1 right). Recording data sets at low temperatures also facilitates measurements of frozen intermediate states of the protein or protein substrate complexes where the substrate is not digested by the protein due to the low mobility at cryogenic temperatures. The main advantage of the monochromatic instrument BioDiff is the possibility to adapt the wavelength between 2.4 Å and 5.6 Å to obtain a compromise between higher scattering yields at longer wavelengths and better resolution at smaller wavelengths. The main detector of BioDiff consists of a neutron imaging plate system in a cylindrical geometry in order to cover a large solid angle. A Li/ZnS scintillator imaged onto a CCD-chip is available for additional detection purposes (see Fig. 1, left). Applications of the BioDiff instrument as a powder diffractometer are also discussed.
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