scholarly journals Competing transfer pathways in direct and indirect dynamic nuclear polarization magic anglespinning nuclear magnetic resonance experiments on HIV-1 capsid assemblies: implications for sensitivity and resolution

2021 ◽  
Vol 2 (1) ◽  
pp. 239-249
Author(s):  
Ivan V. Sergeyev ◽  
Caitlin M. Quinn ◽  
Jochem Struppe ◽  
Angela M. Gronenborn ◽  
Tatyana Polenova
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Large Signal ◽  
Experimental Conditions ◽  
Hiv 1 ◽  
Nuclear Magnetic

Abstract. Dynamic nuclear polarization (DNP)-enhanced magic angle spinning (MAS) nuclear magnetic resonance (NMR) of biological systems is a rapidly growing field. Large signal enhancements make the technique particularly attractive for signal-limited cases, such as studies of complex biological assemblies or at natural isotopic abundance. However, spectral resolution is considerably reduced compared to ambient-temperature non-DNP spectra. Herein, we report a systematic investigation into sensitivity and resolution of 1D and 2D 13C-detected DNP MAS NMR experiments on HIV-1 CA capsid protein tubular assemblies. We show that the magnitude and sign of signal enhancement as well as the homogeneous line width are strongly dependent on the biradical concentration, the dominant polarization transfer pathway, and the enhancement buildup time. Our findings provide guidance for optimal choice of sample preparation and experimental conditions in DNP experiments.

scholarly journals Competing Transfer Pathways in Direct and Indirect Dynamic Nuclear Polarization MAS NMR Experiments on HIV-1 Capsid Assemblies: Implications for Sensitivity and Resolution

2021 ◽  
Author(s):  
Ivan V. Sergeyev ◽  
Caitlin M. Quinn ◽  
Jochem Struppe ◽  
Angela Gronenborn ◽  
Tatyana Polenova
Keyword(s):  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle Spinning ◽  
Optimal Choice ◽  
Mas Nmr ◽  
Magic Angle ◽  
Large Signal ◽  
Experimental Conditions ◽  
Natural Isotopic Abundance ◽  
Hiv 1

Abstract. Dynamic nuclear polarization-enhanced (DNP) magic angle spinning (MAS) NMR of biological systems is a rapidly growing field. Large signal enhancements make the technique particularly attractive for signal-limited cases, such as studies of complex biological assemblies or at natural isotopic abundance. However, spectral resolution is considerably reduced compared to ambient-temperature non-DNP spectra. Herein, we report a systematic investigation into sensitivity and resolution of 1D and 2D 13C-detected DNP MAS NMR experiments on HIV-1 CA tubular assemblies. We show that the magnitude and sign of signal enhancement as well as the homogeneous line width are strongly dependent on the biradical concentration, the dominant polarization transfer pathway, and the enhancement buildup time. Our findings provide guidance for optimal choice of sample preparation and experimental conditions in DNP experiments.

scholarly journals Analysis of the electronic structure of the primary electron donor of photosystem I of <i>Spirodela</i> <i>oligorrhiza</i> by photochemically induced dynamic nuclear polarization (photo-CIDNP) solid-state nuclear magnetic resonance (NMR)

2020 ◽  
Vol 1 (2) ◽  
pp. 261-274
Author(s):  
Geertje J. Janssen ◽  
Patrick Eschenbach ◽  
Patrick Kurle ◽  
Bela E. Bode ◽  
Johannes Neugebauer ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electron Donor ◽  
Photosystem I ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle ◽  
Chl A ◽  
Functional Symmetry ◽  
Nuclear Magnetic

Abstract. The electron donor in photosystem I (PSI), the chlorophyll dimer P700, is studied by photochemically induced dynamic nuclear polarization (photo-CIDNP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) on selectively 13C and uniformly 15N labeled PSI core preparations (PSI-100) obtained from the aquatic plant duckweed (Spirodela oligorrhiza). Light-induced signals originate from the isotope-labeled nuclei of the cofactors involved in the spin-correlated radical pair forming upon light excitation. Signals are assigned to the two donor cofactors (Chl a and Chl a') and the two acceptor cofactors (both Chl a). Light-induced signals originating from both donor and acceptor cofactors demonstrate that electron transfer occurs through both branches of cofactors in the pseudo-C2 symmetric reaction center (RC). The experimental results supported by quantum chemical calculations indicate that this functional symmetry occurs in PSI despite similarly sized chemical shift differences between the cofactors of PSI and the functionally asymmetric special pair donor of the bacterial RC of Rhodobacter sphaeroides. This contributes to converging evidence that local differences in time-averaged electronic ground-state properties, over the donor are of little importance for the functional symmetry breaking across photosynthetic RC species.

scholarly journals Fast and accurate MAS–DNP simulations of large spin ensembles

2017 ◽  
Vol 19 (5) ◽  
pp. 3506-3522 ◽  
Author(s):  
Frédéric Mentink-Vigier ◽  
Shimon Vega ◽  
Gaël De Paëpe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle Spinning ◽  
Successful Implementation ◽  
Magic Angle ◽  
Angle Spinning ◽  
Large Spin

A deeper understanding of parameters affecting Magic Angle Spinning Dynamic Nuclear Polarization (MAS–DNP), an emerging nuclear magnetic resonance hyperpolarization method, is crucial for the development of new polarizing agents and the successful implementation of the technique at higher magnetic fields (>10 T).

Nuclear magnetic resonance (NMR) studies of sintering effects on the lithium ion dynamics in Li1.5Al0.5Ti1.5(PO4)3

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edda Winter ◽  
Philipp Seipel ◽  
Tatiana Zinkevich ◽  
Sylvio Indris ◽  
Bambar Davaasuren ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lithium Ion ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Nmr Studies ◽  
Lithium Ions ◽  
Jump Dynamics ◽  
Nuclear Magnetic

Abstract Various nuclear magnetic resonance (NMR) methods are combined to study the structure and dynamics of Li1.5Al0.5Ti1.5(PO4)3 (LATP) samples, which were obtained from sintering at various temperatures between 650 and 900 °C. 6Li, 27Al, and 31P magic angle spinning (MAS) NMR spectra show that LATP crystallites are better defined for higher calcination temperatures. Analysis of 7Li spin-lattice relaxation and line-shape changes indicates the existence of two species of lithium ions with clearly distinguishable jump dynamics, which can be attributed to crystalline and amorphous sample regions, respectively. An increase of the sintering temperature leads to higher fractions of the fast lithium species with respect to the slow one, but hardly affects the jump dynamics in either of the phases. Specifically, the fast and slow lithium ions show jumps in the nanoseconds regime near 300 and 700 K, respectively. The activation energy of the hopping motion in the LATP crystallites amounts to ca. 0.26 eV. 7Li field-gradient diffusometry reveals that the long-range ion migration is limited by the sample regions featuring slow transport. The high spatial resolution available from the high static field gradients of our setup allows the observation of the lithium ion diffusion inside the small (<100 nm) LATP crystallites, yielding a high self-diffusion coefficient of D = 2 × 10−12 m2/s at room temperature.

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