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Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals

The NMR pulse sequence CODEX (centerband‐only detection of exchange) is a widely used method to report on the number of magnetically inequivalent spins that exchange magnetization via spin diffusion. For crystals, this rules out certain symmetries, and the rate of equilibration is sensitive to dista...

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Autores principales: Xue, Kai, Dervisoglu, Riza, Sowa, Heidrun, Andreas, Loren B.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7497148/
https://www.ncbi.nlm.nih.gov/pubmed/32558171
http://dx.doi.org/10.1002/cphc.202000517
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author Xue, Kai
Dervisoglu, Riza
Sowa, Heidrun
Andreas, Loren B.
author_facet Xue, Kai
Dervisoglu, Riza
Sowa, Heidrun
Andreas, Loren B.
author_sort Xue, Kai
collection PubMed
description The NMR pulse sequence CODEX (centerband‐only detection of exchange) is a widely used method to report on the number of magnetically inequivalent spins that exchange magnetization via spin diffusion. For crystals, this rules out certain symmetries, and the rate of equilibration is sensitive to distances. Here we show that for (13)C CODEX, consideration of natural abundance spins is necessary for crystals of high complexity, demonstrated here with the amino acid phenylalanine. The NMR data rule out the C(2) space group that was originally reported for phenylalanine, and are only consistent with a larger unit cell containing eight magnetically inequivalent molecules. Such an expanded cell was recently described based on single crystal data. The large unit cell dictates the use of long spin diffusion times of more than 200 seconds, in order to equilibrate over the entire unit cell volume of 1622 Å(3).
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spelling pubmed-74971482020-09-25 Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals Xue, Kai Dervisoglu, Riza Sowa, Heidrun Andreas, Loren B. Chemphyschem Communications The NMR pulse sequence CODEX (centerband‐only detection of exchange) is a widely used method to report on the number of magnetically inequivalent spins that exchange magnetization via spin diffusion. For crystals, this rules out certain symmetries, and the rate of equilibration is sensitive to distances. Here we show that for (13)C CODEX, consideration of natural abundance spins is necessary for crystals of high complexity, demonstrated here with the amino acid phenylalanine. The NMR data rule out the C(2) space group that was originally reported for phenylalanine, and are only consistent with a larger unit cell containing eight magnetically inequivalent molecules. Such an expanded cell was recently described based on single crystal data. The large unit cell dictates the use of long spin diffusion times of more than 200 seconds, in order to equilibrate over the entire unit cell volume of 1622 Å(3). John Wiley and Sons Inc. 2020-07-13 2020-08-04 /pmc/articles/PMC7497148/ /pubmed/32558171 http://dx.doi.org/10.1002/cphc.202000517 Text en © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Communications
Xue, Kai
Dervisoglu, Riza
Sowa, Heidrun
Andreas, Loren B.
Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title_full Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title_fullStr Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title_full_unstemmed Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title_short Centerband‐Only Detection of Exchange NMR with Natural‐Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals
title_sort centerband‐only detection of exchange nmr with natural‐abundance correction reveals an expanded unit cell in phenylalanine crystals
topic Communications
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7497148/
https://www.ncbi.nlm.nih.gov/pubmed/32558171
http://dx.doi.org/10.1002/cphc.202000517
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