Journal article
From the gas phase to aqueous solution: Vibrational spectroscopy, Raman optical activity and conformational structure of carbohydrates
Chemistry Department, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, UK1
WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK2
Structural investigations of isolated and hydrated glucose, galactose and lactose structures in the gas phase based upon infra-red ion dip (IRID) spectroscopy conducted at low temperatures, are linked with parallel investigations conducted in aqueous solution at 298K based upon measurements of their vibrational Raman and Raman optical activity (ROA) spectra. ‘Basis sets’ of computed (gas phase) Raman and ROA spectra associated with their low-lying conformational structures are used to construct ‘weighted sums’ which can approximate their experimental Raman and ROA spectra recorded in solution and provide estimates of their conformational population distributions in aqueous solution at 298K; they are compared with estimates based upon analysis of NMR measurements and molecular mechanics and molecular dynamics calculations.
The altered conformational preferences in the singly hydrated complexes of glucose and galactose isolated in the gas phase, appear to be sustained in aqueous solution, supporting the view that explicit hydration provides a key influence on their conformational preferences in solution. On the other hand, the conformational preference of the isolated β(1→4) disaccharide, lactose which resists conformational alteration when singly hydrated, is altered when it is transferred to aqueous solution at 298K.
The computational evidence suggests the control is exerted by entropic effects associated with a loosening of the structure around the glycosidic linkage.
Language: | English |
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Year: | 2006 |
Pages: | 193-200 |
ISSN: | 18732798 and 13873806 |
Types: | Journal article |
DOI: | 10.1016/j.ijms.2006.01.031 |