This title appears in the Scientific Report :
2019
Please use the identifier:
http://hdl.handle.net/2128/24006 in citations.
Neutron Protein Crystallography
Neutron Protein Crystallography
With the advent of new instruments (e. g. Imagine at HFIR, MANDI at SNS and BIODIFF at FRMII) neutron protein crystallography has seen a resurrection from the past pioneering work by Goldstein. New sample environment options at the instruments and a growing user community have greatly enhanced the o...
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Personal Name(s): | Schrader, Tobias Erich (Corresponding author) |
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Contributing Institute: |
Heinz Maier-Leibnitz Zentrum; MLZ Neutronenstreuung; JCNS-1 JCNS-FRM-II; JCNS-FRM-II |
Imprint: |
2019
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Conference: | Russia 2019-02-27 - 2019-02-27 |
Document Type: |
Lecture |
Research Program: |
Soft Matter, Health and Life Sciences FRM II / MLZ Jülich Centre for Neutron Research (JCNS) |
Subject (ZB): | |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
With the advent of new instruments (e. g. Imagine at HFIR, MANDI at SNS and BIODIFF at FRMII) neutron protein crystallography has seen a resurrection from the past pioneering work by Goldstein. New sample environment options at the instruments and a growing user community have greatly enhanced the outcome of the existing neutron diffractometers optimized for large unit cells. Measurements at 100 K in a nitrogen gas stream (cryostream) are now routinely possible at neutron diffractometers. Efforts to increase the flux at the sample position and to reduce the background at the detector enables one to measure smaller and smaller protein crystals down to 0.1 mm3 in volume. The neutron single crystal diffractometer BIODIFF at the research reactor Heinz Maier-Leibnitz (FRM II) is especially designed to collect data from crystals with large unit cells. The main field of its application is the structural analysis of proteins, especially the determination of hydrogen atom positions. BIODIFF is a joint project of the Jülich Centre for Neutron Science (JCNS) and the FRM II. BIODIFF is designed as a monochromatic instrument with a narrow wavelength spread of less than 3 %. To cover a large solid angle the main detector of BIODIFF consists of a neutron imaging plate in a cylindrical geometry with online read-out capability. With a radius of 200 mm and a height of 450 mm it covers a solid angle of approximately 2π with a spatial resolution of up to 125 µm. An optical CCD-camera pointing at the sample position is used to quickly align the sample with respect to the neutron beam. The main advantage of BIODIFF is the possibility to adapt the wavelength to the size of the unit cell of the sample crystal while operating with a clean monochromatic beam that keeps the background level low. BIODFF is equipped with a standard Oxford Cryosystem “Cryostream 700+” which allows measurements in the temperature range from 90 K up to 500 K. A new kappa goniometer head was added recently. This allows an automated tilting of the crystal in order to increase the completeness of the data set when recording another set of frames in the tilted geometry without the need to take the crystal off from the goniometer head. Typical scientific questions addressed are the determination of protonation states of amino acid side chains in proteins and the characterization of the hydrogen bonding networks between the protein active centre and an inhibitor or substrate. One application example is the improvement of antibiotic drugs. Many bacteria secret a protein called -lactamase into their environment. This protein is able to hydrolyse the four membered carbon atom ring in beta-lactam antibiotics. These antibiotics are thereby destroyed and are not harmful to the bacteria any more. This mechanism causes great problems in hospitals. With neutron protein crystallography we were able to find a deuterium atom at the amino acid side chain glutamate 166 in the beta-lactamase protein carrying a transition state analogue. This transition state analogue stops the enzymatic reaction in its first acylation step. Thereby one could identify glutamate 166 as the important base taking over the hydrogen atom in the acylation step. Improved antibiotics should find ways to bind to this side chain in order to prevent its action as a base. Or, an additional drug has to be given which blocks the beta-lactamase protein efficiently such the antibiotics can work effectively. |