Solid-state deuterium NMR and molecular modeling studies of conformationaldynamics in carbohydrates

Citation
B. Stevensson et al., Solid-state deuterium NMR and molecular modeling studies of conformationaldynamics in carbohydrates, J PHYS CH B, 104(25), 2000, pp. 6065-6070
Citations number
34
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
104
Issue
25
Year of publication
2000
Pages
6065 - 6070
Database
ISI
SICI code
1520-6106(20000629)104:25<6065:SDNAMM>2.0.ZU;2-G
Abstract
We report a deuterium nuclear magnetic resonance (NMR) investigation of oct a-O-decanoylthio-beta,beta-trehalose (TTH-10) in the solid state. For the i nterpretation of deuterium NMR line shapes and spin-lattice relaxation rate s, a two-site exchange model was invoked. The motional amplitude for the C- D vector in TTH-10 molecule was estimated to 72 degrees, while the relative populations of the two sites were assumed to be temperature dependent. Fro m the longitudinal deuterium relaxation rates, correlation times for the dy namic process were derived. We found these to be approximately 50 ns at 20 degrees C and 30 ns at 90 degrees C. In addition to NMR experiments, molecu lar dynamics (MD) computer simulations of octa-O-acetylthio-beta,beta-treha lose (TTH-2) and an oxygen analogue, octa-O-acetyl-beta,beta-trehalose (TH- 2), were performed. The analysis of the two torsion angles relevant for the glycosidic linkage indicates that the conformations of the TTH-2 molecule essentially correspond to two states. This observation gives strong support for our assumption about the two-site exchange model used for interpretati on of deuterium solid-state experiments.