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Redetermined crystal structure of α-dl-me­thio­nine at 340 K

Two forms, α and β, are known for the racemic amino acid dl-me­thio­nine, C(5)H(11)NO(2)S. The phase transition between them, taking place around 326 K, is associated with sliding at the central inter­faces of the hydro­phobic regions in the crystal, leaving the hydrogen-bonding pattern unperturbed....

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Autores principales: Görbitz, Carl Henrik, Qi, Lianglin, Mai, Ngan Thi Kim, Kristiansen, Håvard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4257343/
https://www.ncbi.nlm.nih.gov/pubmed/25484739
http://dx.doi.org/10.1107/S1600536814022211
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author Görbitz, Carl Henrik
Qi, Lianglin
Mai, Ngan Thi Kim
Kristiansen, Håvard
author_facet Görbitz, Carl Henrik
Qi, Lianglin
Mai, Ngan Thi Kim
Kristiansen, Håvard
author_sort Görbitz, Carl Henrik
collection PubMed
description Two forms, α and β, are known for the racemic amino acid dl-me­thio­nine, C(5)H(11)NO(2)S. The phase transition between them, taking place around 326 K, is associated with sliding at the central inter­faces of the hydro­phobic regions in the crystal, leaving the hydrogen-bonding pattern unperturbed. For the high-temperature α phase, only a structure of rather low quality has been available [R factor = 0.118, no H-atom coordinates; Taniguchi et al. (1980 ▶). Bull. Chem. Soc. Jpn, 53, 803–804]. We here present accurate structural data for this polymorph [R(F) = 0.049], which are compared with other related amino acid structures with similar properties. We report for the first time that the side chain of this phase has a minor disorder component [occupancy 0.0491 (18)] with a gauche+ rather than a gauche− conformation for the N—C—C—C group. In the crystal of the title compound, N—H⋯O hydrogen bonds link the mol­ecules into (100) sheets.
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spelling pubmed-42573432014-12-05 Redetermined crystal structure of α-dl-me­thio­nine at 340 K Görbitz, Carl Henrik Qi, Lianglin Mai, Ngan Thi Kim Kristiansen, Håvard Acta Crystallogr Sect E Struct Rep Online Research Communications Two forms, α and β, are known for the racemic amino acid dl-me­thio­nine, C(5)H(11)NO(2)S. The phase transition between them, taking place around 326 K, is associated with sliding at the central inter­faces of the hydro­phobic regions in the crystal, leaving the hydrogen-bonding pattern unperturbed. For the high-temperature α phase, only a structure of rather low quality has been available [R factor = 0.118, no H-atom coordinates; Taniguchi et al. (1980 ▶). Bull. Chem. Soc. Jpn, 53, 803–804]. We here present accurate structural data for this polymorph [R(F) = 0.049], which are compared with other related amino acid structures with similar properties. We report for the first time that the side chain of this phase has a minor disorder component [occupancy 0.0491 (18)] with a gauche+ rather than a gauche− conformation for the N—C—C—C group. In the crystal of the title compound, N—H⋯O hydrogen bonds link the mol­ecules into (100) sheets. International Union of Crystallography 2014-10-15 /pmc/articles/PMC4257343/ /pubmed/25484739 http://dx.doi.org/10.1107/S1600536814022211 Text en © Görbitz et al. 2014 http://creativecommons.org/licenses/by/2.0/uk/ This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
spellingShingle Research Communications
Görbitz, Carl Henrik
Qi, Lianglin
Mai, Ngan Thi Kim
Kristiansen, Håvard
Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title_full Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title_fullStr Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title_full_unstemmed Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title_short Redetermined crystal structure of α-dl-me­thio­nine at 340 K
title_sort redetermined crystal structure of α-dl-me­thio­nine at 340 k
topic Research Communications
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4257343/
https://www.ncbi.nlm.nih.gov/pubmed/25484739
http://dx.doi.org/10.1107/S1600536814022211
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