UTOPIA NMR: activating unexploited magnetization using interleaved low-gamma detection
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A growing number of nuclear magnetic resonance (NMR) spectroscopic studies are impaired by the limited information content provided by the standard set of experiments conventionally recorded. This is particularly true for studies of challenging biological systems including large, unstructured, membrane-embedded and/or paramagnetic proteins. Here we introduce the concept of unified time-optimized interleaved acquisition NMR (UTOPIA-NMR) for the unified acquisition of standard high-γ (e.g. 1H) and low-γ (e.g. 13C) detected experiments using a single receiver. Our aim is to activate the high level of polarization and information content distributed on low-γ nuclei without disturbing conventional magnetization transfer pathways. We show that using UTOPIA-NMR we are able to recover nearly all of the normally non-used magnetization without disturbing the standard experiments. In other words, additional spectra, that can significantly increase the NMR insights, are obtained for free. While we anticipate a broad range of possible applications we demonstrate for the soluble protein Bcl-xL (ca. 21 kDa) and for OmpX in nanodiscs (ca. 160 kDa) that UTOPIA-NMR is particularly useful for challenging protein systems including perdeuterated (membrane) proteins.
KeywordsInterleaved acquisition Low-γ nuclei UTOPIA-NMR 13C-detection
The authors acknowledge access to the Jülich-Düsseldorf Biomolecular NMR Center. We thank Eriks Kupce for helpful discussions. This work was supported by Grants from the German Academic Exchange Service (DAAD) and the German Research Foundation (DFG) (ET 103/2-1) to M.E. and from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 660258 to A.V.. G.W. acknowledges support by National Institutes of Health (NIH) Grants GM047467, GM075879. Acquisition and maintenance of instruments used for this research were supported by NIH Grants EB002026 and S10 RR026417.
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Conflict of interest
The authors declare no competing financial interests.
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