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Schmidt P, Vogel A, Schwarze B, Seufert F, Licha K, Wycisk V, Kilian W, Hildebrand PW, Mitschang L. Towards Probing Conformational States of Y2 Receptor Using Hyperpolarized 129Xe NMR. Molecules 2023; 28:molecules28031424. [PMID: 36771089 PMCID: PMC9919357 DOI: 10.3390/molecules28031424] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
G protein-coupled receptors can adopt many different conformational states, each of them exhibiting different restraints towards downstream signaling pathways. One promising strategy to identify and quantify this conformational landscape is to introduce a cysteine at a receptor site sensitive to different states and label this cysteine with a probe for detection. Here, the application of NMR of hyperpolarized 129Xe for the detection of the conformational states of human neuropeptide Y2 receptor is introduced. The xenon trapping cage molecule cryptophane-A attached to a cysteine in extracellular loop 2 of the receptor facilitates chemical exchange saturation transfer experiments without and in the presence of native ligand neuropeptide Y. High-quality spectra indicative of structural states of the receptor-cage conjugate were obtained. Specifically, five signals could be assigned to the conjugate in the apo form. After the addition of NPY, one additional signal and subtle modifications in the persisting signals could be detected. The correlation of the spectroscopic signals and structural states was achieved with molecular dynamics simulations, suggesting frequent contact between the xenon trapping cage and the receptor surface but a preferred interaction with the bound ligand.
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Affiliation(s)
- Peter Schmidt
- Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Alexander Vogel
- Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Benedikt Schwarze
- Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Florian Seufert
- Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Kai Licha
- Institute of Chemistry and Biochemistry, Freie Universitaet Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - Virginia Wycisk
- Institute of Chemistry and Biochemistry, Freie Universitaet Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - Wolfgang Kilian
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Abbestrasse 2-12, 10587 Berlin, Germany
| | - Peter W. Hildebrand
- Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany
| | - Lorenz Mitschang
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Abbestrasse 2-12, 10587 Berlin, Germany
- Correspondence:
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Mitschang L, Korchak S, Kilian W, Riemer T. Comprehensive Quantitative and Calibration-Free Evaluation of Hyperpolarized Xenon-Host Interaction by Multiparametric NMR. Anal Chem 2022; 94:2561-2568. [PMID: 35089685 DOI: 10.1021/acs.analchem.1c04482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The probing of microscopic environments by hyperpolarized xenon NMR has spurred investigations in supramolecular chemistry as well as important biosensing and molecular imaging applications. While xenon exchange with host structures at micromolar concentrations and below can be readily detected, a quantitative analysis is limited, requiring complementary experimentation by different methodologies and thus lacking completeness and compromising the validity and comparability of numerical results. Here, a new NMR measurement and data analysis approach is introduced for the comprehensive characterization of the host-xenon binding dynamics. The application of chemical exchange saturation transfer of hyperpolarized 129Xe under parametric modulation of the saturation RF amplitude and xenon gas saturation of the solution enables a delineation of exchange mechanisms and, through modeling, a numerical estimation of the various reaction rate constants (and thus magnetization exchange rate constants), the xenon affinity, and the total host molecule concentration. Only the numerical xenon solubility is additionally required for input, a quantity that has a low impact on the measurement uncertainty and is derivable from metrological data collections. Signal calibration by a reference material may thus be avoided, qualifying the method as calibration-free. For demonstration a xenon exchange with the host cucurbit[6]uril at low concentration is investigated, with the numerical results being validated by standard quantitative NMR data obtained at high concentration. The readiness to evaluate xenon exchange for the one sample at hand and in a single experimental attempt by the proposed method may allow comprehensive quantitative studies in supramolecular chemistry, biomacromolecular structure and dynamics, and sensing.
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Affiliation(s)
- Lorenz Mitschang
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Sergey Korchak
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Wolfgang Kilian
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Thomas Riemer
- University of Leipzig, Institute of Medical Physics and Biophysics, Medical Department, Härtelstraße 16-18, 04107 Leipzig, Germany
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3
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Jiang W, Guo Q, Luo Q, Zhang X, Yuan Y, Li H, Zhou X. Molecular Concentration Determination Using Long-Interval Chemical Exchange Inversion Transfer (CEIT) NMR Spectroscopy. J Phys Chem Lett 2021; 12:8652-8657. [PMID: 34472873 DOI: 10.1021/acs.jpclett.1c02239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Functionalized hyperpolarized xenon "cage" molecules have often been used for ultrasensitive detection of biomolecules and microenvironment properties. However, the rapid and accurate measurement of molecule concentration is still a challenge. Here, we report a molecule concentration measurement method using long-interval chemical exchange inversion transfer (CEIT) NMR spectroscopy. The molecule concentration can be quantitatively measured with only 2 scans, which shortens the acquisition time by about 10 times compared to conventional Hyper-CEST (chemical exchange saturation transfer) z-spectrum method. Moreover, we found that the accuracy of concentration determination would be the best when the CEIT effect is 1-1/e or close to it, and a relative deviation of CrA-(COOH)6 less than ±1% has been achieved by only a one-step optimization of the number of cycles. The proposed method enables efficient and accurate determination of molecule concentration, which provides a potential way for rapid quantitative molecular imaging applications.
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Affiliation(s)
- Weiping Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Qianni Guo
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Qing Luo
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
| | - Xiaoxiao Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
| | - Yaping Yuan
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Haidong Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Xin Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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McHugh CT, Durham PG, Kelley M, Dayton PA, Branca RT. Magnetic Resonance Detection of Gas Microbubbles via HyperCEST: A Path Toward Dual Modality Contrast Agent. Chemphyschem 2021; 22:1219-1228. [PMID: 33852753 PMCID: PMC8494452 DOI: 10.1002/cphc.202100183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/14/2021] [Indexed: 11/06/2022]
Abstract
Gas microbubbles are an established clinical ultrasound contrast agent. They could also become a powerful magnetic resonance (MR) intravascular contrast agent, but their low susceptibility-induced contrast requires high circulating concentrations or the addition of exogenous paramagnetic nanoparticles for MR detection. In order to detect clinical in vivo concentrations of raw microbubbles via MR, an alternative detection scheme must be used. HyperCEST is an NMR technique capable of indirectly detecting signals from very dilute molecules (concentrations well below the NMR detection threshold) that exchange hyperpolarized 129 Xe. Here, we use quantitative hyperCEST to show that microbubbles are very efficient hyperCEST agents. They can accommodate and saturate millions of 129 Xe atoms at a time, allowing for their indirect detection at concentrations as low as 10 femtomolar. The increased MR sensitivity to microbubbles achieved via hyperCEST can bridge the gap for microbubbles to become a dual modality contrast agent.
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Affiliation(s)
- Christian T. McHugh
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Phillip G. Durham
- Department of Pharmacoengineering and Molecular Pharmaceutics, The University of North arolina at Chapel Hill, Chapel Hill, NC 27599
| | - Michele Kelley
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Paul A. Dayton
- Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Department of Biomedical Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Rosa T. Branca
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Biomedical Research Imaging Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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Korchak S, Riemer T, Kilian W, Mitschang L. Quantitative Assessment of Xenon Exchange Kinetics with Cucurbit[6]uril in Physiological Saline. Chemphyschem 2018; 19:1859-1865. [PMID: 29855138 DOI: 10.1002/cphc.201800048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Indexed: 11/10/2022]
Abstract
Cucurbit[6]uril and xenon form supramolecular complexes that are of great potential for biosensing by NMR. This host-guest system acts alike a signaler in sensors facilitating the ultrasensitive detection of biomarkers by saturation transfer of chemically exchanging, hyperpolarized 129 Xe. Here, the exchange process is evaluated by NMR exchange spectroscopy utilizing the preparation of anti-parallel longitudinal magnetization with respect to free and host-bound xenon and the variation of xenon concentration. Evidence for dissociative as well as degenerate exchange mechanisms is revealed by a linear regression analysis of the determined exchange rates resulting in rate coefficients of 1131±11 s-1 (2390±70 s-1 ) and 108500±4900 M-1 s-1 (174200±13900 M-1 s-1 ), respectively, and an affinity constant of 289±8 M-1 (278±14 M-1 ) in physiological saline at 298 K (310 K). The results elucidate the supramolecular exchange and underpin the high efficacy for biosensing of this host-guest system. The approach is generally applicable to enhanced host-xenon exchange dynamics, yet slow on the NMR timescale, for quantitative kinetics and biosensing analyses.
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Affiliation(s)
- Sergey Korchak
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587, Berlin, Germany
- Present address: Max Planck Research Group NMR Signal Enhancement, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Thomas Riemer
- Medical Department, Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04107, Leipzig, Germany
| | - Wolfgang Kilian
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587, Berlin, Germany
| | - Lorenz Mitschang
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587, Berlin, Germany
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