Enhanced nuclear-spin hyperpolarization of amino acids and proteins via reductive radical quenchers

Yang, Hanming; Mecha, Miranda F.; Goebel, Collin P.; Cavagnero, Silvia

doi:10.1016/j.jmr.2021.106912

Cited by 10 publications

(13 citation statements)

References 48 publications

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“…Earlier identification of chemically induced dynamic nuclear polarization (CIDNP) , in organic reactions led to the development of a photochemically enhanced NMR approach known as photo-CIDNP. While originally employed to assess solvent exposure, this technique has more recently been employed to significantly increase NMR sensitivity in solution at a high applied field. − Photo-CIDNP is devoid of most of the drawbacks of other approaches listed in the previous paragraph. This technique requires aromatic moieties and benefits from an O 2 -free environment.…”

Section: Introductionmentioning

confidence: 99%

“…The latter features enable long-term signal averaging and multidimensional NMR of extremely dilute samples. This technology leads to an enhanced signal-to-noise ratio (S/N) of tryptophan (Trp) and tyrosine (Tyr), either as free amino acids or within polypeptides and proteins. ,− Remarkably, high LC-photo-CIDNP enhancements are observed for C α nuclei of aromatic amino acids, likely due to their high hyperfine coupling constants, , enabling the efficient detection of 1 H α – 13 C α pairs. The C α chemical shifts are particularly useful because they are diagnostic of the backbone secondary structure in proteins .…”

Section: Introductionmentioning

confidence: 99%

“…More recent studies showed that LC-photo-CIDNP hyperpolarization can be further enhanced in the presence of low-μM concentrations of reductive radical quenchers including ascorbic acid, a.k.a. vitamin C (VC), leading to the detection of 200 nM aromatic amino acids . Despite the above advances, it is highly desirable to render liquid-state NMR spectroscopy even more sensitive so that it approaches detection limits of other leading techniques, e.g., fluorescence and mass spectrometry.…”

Section: Introductionmentioning

confidence: 99%

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Selective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration

Yang

Mickles

et al. 2022

J. Am. Chem. Soc.

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NMR spectroscopy is a powerful tool to investigate molecular structure and dynamics. The poor sensitivity of this technique, however, limits its ability to tackle questions requiring dilute samples. Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) is an optically enhanced NMR technology capable of addressing the above challenge by increasing the detection limit of aromatic amino acids in solution up to 1000-fold, either in isolation or within proteins. Here, we show that the absence of NMR-active nuclei close to a magnetically active site of interest (e.g., the structurally diagnostic 1Hα–13Cα pair of amino acids) is expected to significantly increase LC-photo-CIDNP hyperpolarization. Then, we exploit the spin-diluted tryptophan isotopolog Trp-α-13C-β,β,2,4,5,6,7-d7 and take advantage of the above prediction to experimentally achieve a ca 4-fold enhancement in NMR sensitivity over regular LC-photo-CIDNP. This advance enables the rapid (within seconds) detection of 20 nM concentrations or the molecule of interest, corresponding to a remarkable 3 ng detection limit. Finally, the above Trp isotopolog is amenable to incorporation within proteins and is readily detectable at a 1 μM concentration in complex cell-like media, including Escherichia coli cell-free extracts.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration

Yang

Mickles

et al. 2022

J. Am. Chem. Soc.

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“…Fourth, hyperpolarization generation requires very little and cheap hardware and is quite mobile. The replacement of lasers by high-power LEDs for photo-CIDNP studies was successfully investigated by [39][40][41][42] and references therein.…”

Section: Abbreviationsmentioning

confidence: 99%

“…In both 1D and 2D MR techniques, valuable information can be obtained by changing the signal intensity or phase. Recently, advances have been made to detect even the smallest concentrations or amounts of substances [6,[42][43][44] but the focus in this study is more on investigating the feasibility of a background-free approach using 19 F NMR and 19 F MRI.…”

Section: Abbreviationsmentioning

confidence: 99%

LED-Based Photo-CIDNP Hyperpolarization Enables 19F MR Imaging and 19F NMR Spectroscopy of 3-Fluoro-DL-tyrosine at 0.6 T

et al. 2022

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Although 19F has high potential to serve as a background-free molecular marker in bioimaging, the molar amount of marker substance is often too small to enable 19F MR imaging or 19F NMR spectroscopy with a sufficiently high signal-to-noise ratio (SNR). Hyperpolarization methods such as parahydrogen-based hyperpolarization or dynamic nuclear polarization (DNP) can significantly improve the SNR, but require expensive and complex sample preparation and the removal of toxic catalysts and solvents. Therefore, we used the biologically compatible model of the fluorinated amino acid 3-Fluoro-DL-tyrosine with riboflavin 5ʹ-monophosphate (FMN) as a chromophore dissolved in D2O with 3.4% H2Odest., allowing to transform light energy into hyperpolarization of the 19F nucleus via photo-chemically induced dynamic nuclear polarization (photo-CIDNP). We used a low-cost high-power blue LED to illuminate the sample replacing traditionally used laser excitation, which is both potentially harmful and costly. For the first time, we present results of hyperpolarized 19F MRI and 19F NMR performed with a low-cost 0.6 T benchtop MRI system. The device allowed simultaneous dual-channel 1H/19F NMR. 19F imaging was performed with a (0.94 mm)2 in-plane resolution. This enabled the spatial resolution of different degrees of hyperpolarization within the sample. We estimated the photo-CIDNP-based 19F signal enhancement at 0.6 T to be approximately 465. FMN did not bleach out even after multiple excitations, so that the signal-to-noise ratio could be further improved by averaging hyperpolarized signals. The results show that the easy-to-use experimental setup has a high potential to serve as an efficient preclinical tool for hyperpolarization studies in bioimaging.

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Magnetic-Field Dependence of LC-Photo-CIDNP in the Presence of Target Molecules Carrying a Quasi-Isolated Spin Pair

Yang²,

Hofstetter³

et al. 2022

Appl Magn Reson

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Enhanced nuclear-spin hyperpolarization of amino acids and proteins via reductive radical quenchers

Cited by 10 publications

References 48 publications

Selective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration

Selective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration

LED-Based Photo-CIDNP Hyperpolarization Enables 19F MR Imaging and 19F NMR Spectroscopy of 3-Fluoro-DL-tyrosine at 0.6 T

Magnetic-Field Dependence of LC-Photo-CIDNP in the Presence of Target Molecules Carrying a Quasi-Isolated Spin Pair

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