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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....
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
International Union of Crystallography
2014
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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. |
format | Online Article Text |
id | pubmed-4257343 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | International Union of Crystallography |
record_format | MEDLINE/PubMed |
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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