Neutron Protein Crystallography and equilibrium dynamics

Schrader, Tobias Erich

Lecture (Invited)

FZJ-2020-00489

Neutron Protein Crystallography and equilibrium dynamics

Schrader, T. E. (Corresponding author)FZJ*

2019

Lecture at FEBS Practical Course, Biomolecules in Action II ,DESY (Hamburg, Germany), 25 Jun 2019 - 25 Jun 2019

Please use a persistent id in citations: http://hdl.handle.net/2128/24129

Abstract: In this lecture, an introduction into the method of neutron protein crystallography will be given and the differences to x-ray crystallography will be highlighted: As opposed to x-rays, neutrons are scattered from the nuclei and can therefore locate hydrogen atoms. Therefore, 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. The neutron single crystal diffractometer BIODIFF will serve as an example of a neutron protein crystallography beam line. It is located at the Heinz Maier-Leibnitz Zentrum, MLZ, at the research reactor (FRM II) in Garching, Germany. BIODIFF is a joint project of the Jülich Centre for Neutron Science (JCNS) and the Technical University of Munich (TUM). 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. Efforts to increase the flux at the sample position and to reduce the background at the detector have led to the ability to measure smaller and smaller protein crystals down to 0.1 mm3 in volume. 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 -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 -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 to the patients which blocks the -lactamase protein efficiently such that the antibiotics can work effectively agian. The technique of neutron protein crystallography uses elastic neutron scattering and gives information on the structure of the protein. Inelastic neutron scattering reports on the equilibrium dynamics of proteins in solution. In a short excursion, neutron spin echo spectroscopy, an example of an inelastic, i. e. spectroscopic neutron scattering technique will be introduced which allows to monitor large scale protein motions on a nanosecond timescale. In case of the protein Phosphoglyceratkinase, it will be shown that those motions are necessary for the protein to fulfill its enzymatic function.

Keyword(s): Health and Life (1st) ; Biology (2nd)

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Appears in the scientific report 2019

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OpenAccess