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A New Tool for NMR Crystallography: Complete 13C/15N Assignment of Organic Molecules at Natural Isotopic Abundance Using DNP-Enhanced Solid-State NMR

posted May 28, 2016, 4:11 AM by Daniel Lee
A New Tool for NMR Crystallography: Complete 13C/15N Assignment of Organic Molecules at Natural Isotopic Abundance Using DNP-Enhanced Solid-State NMR
NMR crystallography of organic molecules at natural isotopic abundance (NA) strongly relies on the comparison of assigned experimental and computed NMR chemical shifts. However, a broad applicability of this approach is often hampered by the still limited 1H resolution and/or difficulties in assigning 13C and 15N resonances without the use of structure-based chemical shift calculations. As shown here, such difficulties can be overcome by 13C–13C and for the first time 15N–13C correlation experiments, recorded with the help of dynamic nuclear polarization. We present the complete de novo 13C and 15N resonance assignment at NA of a self-assembled 2′-deoxyguanosine derivative presenting two different molecules in the asymmetric crystallographic unit cell. This de novo assignment method is exclusively based on aforementioned correlation spectra and is an important addition to the NMR crystallography approach, rendering firstly 1H assignment straightforward, and being secondly a prerequisite for distance measurements with solid-state NMR.
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