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31P spin-lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation

31P spin-lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation
31P spin-lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation

Nuclear spin relaxation mechanisms are often difficult to isolate and identify, especially in molecules with internal flexibility. Here we combine experimental work with computation in order to determine the major mechanisms responsible for 31P spin-lattice and singlet order (SO) relaxation in pyrophosphate, a physiologically relevant molecule. Using field-shuttling relaxation measurements (from 2 μT to 9.4 T) and rates calculated from molecular dynamics (MD) trajectories, we identified chemical shift anisotropy (CSA) and spin-rotation as the major mechanisms, with minor contributions from intra- and intermolecular coupling. The significant spin-rotation interaction is a consequence of the relatively rapid rotation of the -PO32− entities around the bridging P-O bonds, and is treated by a combination of MD simulations and quantum chemistry calculations. Spin-lattice relaxation was predicted well without adjustable parameters, and for SO relaxation one parameter was extracted from the comparison between experiment and computation (a correlation coefficient between the rotational motion of the groups).

1463-9076
24239-24246
Korenchan, David E.
9aa08b6b-8a5f-4131-894c-539bc9e838eb
Lu, Jiaqi
995cde48-0e10-41ea-9e45-aee786371859
Sabba, Mohamed
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Dagys, Laurynas
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Brown, Lynda J.
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Levitt, Malcolm H.
bcc5a80a-e5c5-4e0e-9a9a-249d036747c3
Jerschow, Alexej
4809ea26-1ad9-4f59-a7e4-e66ea2ed6692
Korenchan, David E.
9aa08b6b-8a5f-4131-894c-539bc9e838eb
Lu, Jiaqi
995cde48-0e10-41ea-9e45-aee786371859
Sabba, Mohamed
bef5e5e8-18b2-43d9-8969-4a9b25bb8691
Dagys, Laurynas
0de61597-b152-4bee-a934-123a9d2de883
Brown, Lynda J.
75aa95fa-5d27-46a7-9dbe-0f465a664f5b
Levitt, Malcolm H.
bcc5a80a-e5c5-4e0e-9a9a-249d036747c3
Jerschow, Alexej
4809ea26-1ad9-4f59-a7e4-e66ea2ed6692

Korenchan, David E., Lu, Jiaqi, Sabba, Mohamed, Dagys, Laurynas, Brown, Lynda J., Levitt, Malcolm H. and Jerschow, Alexej (2022) 31P spin-lattice and singlet order relaxation mechanisms in pyrophosphate studied by isotopic substitution, field shuttling NMR, and molecular dynamics simulation. Physical Chemistry Chemical Physics, 24 (39), 24239-24246. (doi:10.1039/d2cp03801c).

Record type: Article

Abstract

Nuclear spin relaxation mechanisms are often difficult to isolate and identify, especially in molecules with internal flexibility. Here we combine experimental work with computation in order to determine the major mechanisms responsible for 31P spin-lattice and singlet order (SO) relaxation in pyrophosphate, a physiologically relevant molecule. Using field-shuttling relaxation measurements (from 2 μT to 9.4 T) and rates calculated from molecular dynamics (MD) trajectories, we identified chemical shift anisotropy (CSA) and spin-rotation as the major mechanisms, with minor contributions from intra- and intermolecular coupling. The significant spin-rotation interaction is a consequence of the relatively rapid rotation of the -PO32− entities around the bridging P-O bonds, and is treated by a combination of MD simulations and quantum chemistry calculations. Spin-lattice relaxation was predicted well without adjustable parameters, and for SO relaxation one parameter was extracted from the comparison between experiment and computation (a correlation coefficient between the rotational motion of the groups).

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2022_PCCP_PPi-relaxation_main_revised_final-1 - Accepted Manuscript
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Accepted/In Press date: 18 September 2022
e-pub ahead of print date: 19 September 2022
Published date: 21 October 2022
Additional Information: Funding Information: D. E. K. thanks Christian Bengs and Jamie Whipham for helpful discussions regarding singlet NMR pulse sequences and NMR relaxation. The authors thank Alexey Kiryutin (International Tomography Centre, Novosibirsk, Russia) for sharing the shuttle design. This work was supported in part through the NYU IT High Performance Computing resources, services, and staff expertise (in particular by Dr Shenglong Wang). Funding: National Science Foundation, award no. CHE 2108205 (AJ); Heising-Simons Foundation (AJ); Diamond Jubilee Visiting Fellowship, University of Southampton (AJ); EPSRC-UK, grant numbers EP/P009980/1, EP/T004320/1 and EP/P030491/1 (MHL); European Unions Horizon 2020 research and innovation programme, under the Marie Skłodowska-Curie grant agreement No 891400 (MHL); European Research Council, grant 786707-FunMagResBeacons (MHL). Publisher Copyright: © 2022 The Royal Society of Chemistry.

Identifiers

Local EPrints ID: 472424
URI: http://eprints.soton.ac.uk/id/eprint/472424
ISSN: 1463-9076
PURE UUID: 1275e2e4-d13a-4168-91f0-579e4514cc3e
ORCID for Mohamed Sabba: ORCID iD orcid.org/0000-0003-2707-1821
ORCID for Lynda J. Brown: ORCID iD orcid.org/0000-0002-5678-0814
ORCID for Malcolm H. Levitt: ORCID iD orcid.org/0000-0001-9878-1180

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Date deposited: 05 Dec 2022 17:44
Last modified: 06 Jun 2024 04:04

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Contributors

Author: David E. Korenchan
Author: Jiaqi Lu
Author: Mohamed Sabba ORCID iD
Author: Laurynas Dagys
Author: Lynda J. Brown ORCID iD
Author: Alexej Jerschow

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