Macromolecular Solid-State NMR Research: Application&Method...
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Summer 2010 MAT Seminar Series
Macromolecular Solid-State NMR Research: Application & Method Development


Ümit Akbey
NMR Supported Structural Biology, Leibniz-Institute for Molecular Pharmacology, Robert-Roessle-Str.. 10, 13125 Berlin, Germany


Solid-state nuclear magnetic resonance (ssNMR) spectroscopy has been proven to be a robust and powerful technique for determining structure and dynamics of supramolecular functional materials and biological systems at molecular level. For example, the characterization of supramolecular architectures, such as proton conducting membrane polymers and plastic electronic materials, is of most importance to understand their properties. Solid-state NMR methods can unravel such structure-property relations with the help of fast magic-angle spinning and advanced NMR pulse sequences. In particular, 1H ssNMR spectroscopy is suitable for studying hydrogen-bonding networks, local proton mobility, molecular packing arrangements, and local dynamics without the requirement of isotopic-labeling. Despite its indispensible use in material science and structural biology, ssNMR has the disadvantage of inherent low sensitivity. This is especially an issue when working with “difficult to obtain proteins”, in particular membrane proteins. Such systems can not be obtained large quantities for ssNMR measurements. As a result, methods for sensitivity enhancement are highly welcome to increase the scope of ssNMR. Remarkable success has been achieved recently by using a technique called dynamic nuclear polarization (DNP). This method exploits the transfer of large initial Boltzmann polarization of electron spin states to those of neighboring nuclei. Theoretical nuclear signal enhancements of (e/ I) ~660 can be obtained for 1H nuclei, which
could result in ~106 reduction in experimental time. As a final topic, methods to achieve higher resolution in the ssNMR studies of biological systems will be discussed by protein deuteration. This method results in spectra with resolution similar to liquid-state in both the 1H and 15N/13C dimensions. This approach, combined with an optimization of the proton/deuterium ratio to maximize sensitivity, enables the use of scalarcoupling-based NMR experiments. As a beneficial side-effect of perdeuteration, low-power
decoupling of 1H and 2H is sufficient to obtain 13C line widths less than 0.5 ppm.
References:
1. M. M. Demir, P. Castignolles, Ü. Akbey, G. Wegner. Macromolecules. 40 (12), 4190–4198, 2007.
2. S. Ü. Çelik*, Ü. Akbey*, R. Graf, A. Bozkurt, H. W. Spiess. Phys. Chem. Chem. Phys. 10, 6058–6066, 2008.
3. Ü. Akbey, S. Granados-Focil, E. B. Coughlin, R. Graf, H. W. Spiess. J. Phys. Chem. B. 113, 9151–9160, 2009.
4. Ü. Akbey, H. Oschkinat, B. van Rossum. J. Am. Chem. Soc. 131 (47), 17054–17055, 2009.
5. Ü. Akbey*, S. Lange*, W. T. Franks, R. Linser, K. Rehbein, A. Diehl, B. van Rossum, B. Reif, H. Oschkinat. J.
of Biomol. NMR. 46 (1), 67-73, 2010.
6. Ü. Akbey, W. T. Franks, A. Linden, S. Lange, R. R. Griffin, B. van Rossum, H. Oschkinat. Angew. Chem. Int.
Ed. 2010. doi: 10.1002/anie.201002044.
Monday, 20th of September at 13.30 in G035