Revisiting the phase transition sequence in L-methionine: Description of the disordering mechanism in an essential amino acid
| Autor: | Yannick Guinet, Laurent Paccou, Florence Danède, Alain Hédoux |
|---|---|
| Přispěvatelé: | Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) |
| Rok vydání: | 2022 |
| Předmět: |
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
General Physics and Astronomy [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn] Physical and Theoretical Chemistry [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] |
| Zdroj: | Journal of Chemical Physics Journal of Chemical Physics, 2022, Journal of Chemical Physics, 156 (3), pp.034501. ⟨10.1063/5.0077743⟩ |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | International audience; Raman spectroscopy investigations on L-methionine (L-Met) performed in large temperature range (170 K – 420 K) and in a wide spectral window (5 – 3600 cm-1) have revealed an extended disordering mechanism triggered by thermally activated motions of the terminal side-chain atoms, from 250 K up to 390 K. This very progressive disordering process is characterized by two thermodynamic features, the first corresponding to a broad endotherm (250 K → 310 K) marking the beginning of the process while the second, ending the disordering transformation is a sharp endothermic peak at 390 K. These thermodynamic events are correlated with the softening of lattice vibrations and the increase of the quasielastic scattering, considered as the signatures of displacive phase transitions. The amorphous like band-shape of the low-frequency Raman spectrum collected above 390 K, resulting from the strong anharmonicity of local motions, is contrasting with the detection of additional Bragg peaks above 390 K by X-ray diffraction, consistent with the Cp jump accompanying the endothermic peak. These observations suggest that L-Met is progressively dynamically disordered adopting additional configurations in the crystalline lattice, through rotations of CH3 and the side-chain flexibility not clearly detected by X-ray diffraction. These results should be crucial for considering the stability of dried proteins composed of methionine residues. |
| Databáze: | OpenAIRE |
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