Maximizing NMR signal per unit time by facilitating the e–e–n cross effect DNP rate

Leavesley, Alisa; Jain, Sheetal Kumar; Kamniker, Ilia; Zhang, Hui; Rajca, Suchada; Rajca, Andrzej; Han, Songi

doi:10.1039/c8cp04909b

Cited by 28 publications

(20 citation statements)

References 69 publications

(78 reference statements)

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“…We subsequently described a series of DOTOPA derivatives that have greater solubility at neutral or basic pH in water/glycerol mixtures than does the original DOTOPA compound [19]. Favorable properties of DOTOPA have also been reported by others [20].…”

Section: Introductionmentioning

confidence: 81%

Succinyl-DOTOPA: An effective triradical dopant for low-temperature dynamic nuclear polarization with high solubility in aqueous solvent mixtures at neutral pH

Yau

Jeon

Tycko

2020

Journal of Magnetic Resonance

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We report the synthesis of the nitroxide-based triradical compound succinyl-DOTOPA and the characterization of its performance as a dopant for dynamic nuclear polarization (DNP) experiments in frozen solutions at low temperatures. Compared with previously described DOTOPA derivatives, succinyl-DOTOPA has substantially greater solubility in glycerol/water mixtures with pH > 4 and therefore has wider applicability. Solid state nuclear magnetic resonance (ssNMR) measurements at 9.39 T and 25 K, with magic-angle spinning at 7.00 kHz, show that build-up times of DNP-enhanced, cross-polarized 13 C ssNMR signals are shorter and that signal amplitudes are larger for glycerol/water solutions of L-proline containing succinyl-DOTOPA than for solutions containing the biradical AMUPol, with electron spin concentrations of 15 mM or 30 mM, resulting in greater net sensitivity gains from DNP. In similar measurements at 90 K, AMUPol yields greater net sensitivity, apparently due to its longer electron spin-lattice and spinspin relaxation times. One-and two-dimensional 13 C ssNMR measurements at 25 K on the complex of the 27-residue peptide M13 with the calcium-sensing protein calmodulin, in glycerol/ water with 10 mM succinyl-DOTOPA, demonstrate the utility of this compound in DNP-enhanced ssNMR studies of biomolecular systems.

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Section: Introductionmentioning

confidence: 81%

Succinyl-DOTOPA: An effective triradical dopant for low-temperature dynamic nuclear polarization with high solubility in aqueous solvent mixtures at neutral pH

Yau

Jeon

Tycko

2020

Journal of Magnetic Resonance

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“…1A. As such, this is complementary to recent work studying polarization transfer rates in conventional DNP [62][63][64]. Consider first data in Fig.…”

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confidence: 57%

Rapidly enhanced spin polarization injection in an optically pumped spin ratchet

Adrisha¹,

Blankenship²,

Druga³

et al. 2021

Preprint

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Rapid injection of spin polarization into an ensemble of nuclear spins is a problem of broad interest, spanning dynamic nuclear polarization (DNP) to quantum information science. We report on a strategy to boost the spin injection rate by exploiting electrons that can be rapidly polarized via high-power optical pumping. We demonstrate this in a model system of Nitrogen Vacancy center electrons injecting polarization into a bath of 13 C nuclei in diamond. We innovate an apparatus with thirty lasers to deliver >20W of continuous, nearly isotropic, optical power to the sample with only a minimal temperature increase. This constitutes a substantially higher power than in previous experiments, and through a spin-ratchet polarization transfer mechanism, yields boosts in spin injection rates by over two orders of magnitude. Our experiments also elucidate speed-limits of nuclear spin injection that are individually bottlenecked by rates of electron polarization, polarization transfer to proximal nuclei, and spin diffusion. This work demonstrates opportunities for rapid spin injection employing non-thermally generated electron polarization, and has relevance to a broad class of experimental systems including in DNP, quantum sensing, and spin-based MASERs.

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“…Ice crystalization is also thought to increase paramagnetic quenching of nuclei by freeze concentrating DNP radicals outside of growing ice crystals which are extracting water from the surrounding space to feed crystal growth ( Corzilius et al, 2014 ). The resulting increase in e-e-n polarization transfer at higher radical concentrations leads to reduced enhancement factors and shorter polarization build up times ( Leavesley et al, 2018a ). While the lower T B time of DMSO preserved samples would be consistent with increased radical concentration, possibly due to ice formation, we would expect this phenomenon to be greater in PBS preserved cells in which ice crystal formation would be expected to be greatest.…”

Section: Discussionmentioning

confidence: 99%

Biomolecular Perturbations in In-Cell Dynamic Nuclear Polarization Experiments

Overall

Barnes

2021

Front. Mol. Biosci.

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In-cell DNP is a growing application of NMR to the study of biomolecular structure and function within intact cells. An important unresolved question for in-cell DNP spectroscopy is the integrity of cellular samples under the cryogenic conditions of DNP. Despite the rich literature around cryopreservation of cells in the fields of stem cell/embryonic cell therapeutics, cell line preservation and in cryo-EM applications, the effect of cryopreservation procedures on DNP parameters is unclear. In this report we investigate cell survival and apoptosis in the presence of cryopreserving agents and DNP radicals. We also assess the effects of these reagents on cellular enhancements. We show that the DNP radical AMUPol has no effect on membrane permeability and does not induce apoptosis. Furthermore, the standard aqueous glass forming reagent, comprised of 60/30/10 d8-glycerol/D2O/H2O (DNP juice), rapidly dehydrates cells and induces apoptosis prior to freezing, reducing structural integrity of the sample prior to DNP analysis. Preservation with d6-DMSO at 10% v/v provided similar DNP enhancements per √unit time compared to glycerol preservation with superior maintenance of cell size and membrane integrity prior to freezing. DMSO preservation also greatly enhanced post-thaw survival of cells slow-frozen at 1°C/min. We therefore demonstrate that in-cell DNP-NMR studies should be done with d6-DMSO as cryoprotectant and raise important considerations for the progression of in-cell DNP-NMR towards the goal of high quality structural studies.

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Maximizing NMR signal per unit time by facilitating the e–e–n cross effect DNP rate

Cited by 28 publications

References 69 publications

Succinyl-DOTOPA: An effective triradical dopant for low-temperature dynamic nuclear polarization with high solubility in aqueous solvent mixtures at neutral pH

Succinyl-DOTOPA: An effective triradical dopant for low-temperature dynamic nuclear polarization with high solubility in aqueous solvent mixtures at neutral pH

Rapidly enhanced spin polarization injection in an optically pumped spin ratchet

Biomolecular Perturbations in In-Cell Dynamic Nuclear Polarization Experiments

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