Titre :

Identification of incommensurability in L-leucine: can lattice instabilities be considered as general phenomena in hydrophobic amino acids?

Auteur(s) :

Guinet, Yannick [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Paccou, Laurent [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Danede, Florence [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Derollez, Patrick [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Hedoux, Alain [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]

Titre de la revue :

Physical Chemistry Chemical Physics

Numéro :

24

Pagination :

27023-27030

Date de publication :

2022-11

ISSN :

1463-9076

Discipline(s) HAL :

Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
Physique [physics]/Matière Condensée [cond-mat]/Matière Molle [cond-mat.soft]
Physique [physics]/Matière Condensée [cond-mat]/Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Résumé en anglais : [en]

L-Leucine is an essential amino acid which has been focusing a lot of investigations on its phase transition sequence for more than fifty years. Combining Raman spectroscopy and X-ray diffraction experiments provides a new ...
Lire la suite >L-Leucine is an essential amino acid which has been focusing a lot of investigations on its phase transition sequence for more than fifty years. Combining Raman spectroscopy and X-ray diffraction experiments provides a new interpretation of the second order phase transition extending between 270 and 360 K as a displacive incommensurate-normal phase transition. A soft mode was clearly detected from low-frequency Raman investigations which exhibits the temperature dependence (A·(TC−T)1/2) typical of the temperature behavior of the amplitudon, an excitation specific to incommensurate phases. Simultaneously to the softening of the amplitudon, several very weakly intense X-ray reflections vanish upon heating at 360 K, and thereby are interpreted as satellite reflections. This incommensurability was described as resulting from the freezing of thermally activated hydrophobic side-chain rotations upon cooling in disordered orientations. Raman investigations were also performed on the isomeric amino acid L-norleucine previously identified as undergoing a normal-incommensurate phase transition around 200 K. Comparison of both studies suggests that the temperature behavior of thermally activated local motions generates lattice instabilities. Loss of periodicity can result from the freezing of rotations of molecular moieties in disordered orientations, or from the enhancement of anharmonicity of these rotations. This could be a general phenomenon in hydrophobic amino acids with direct consequences on their applications in the life science area.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
CNRS
INRAE
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Équipe(s) de recherche :

Matériaux Moléculaires et Thérapeutiques

Date de dépôt :

2022-11-24T14:28:10Z
2022-11-24T15:45:48Z
2022-11-25T09:25:41Z