Molecular dynamics and conformational kinetics of mono- and disaccharides in aqueous solution.
Acoustical attenuation spectra between 10 kHz and 2 GHz, complex dielectric spectra between 300 kHz and 40 GHz, and time-resolved non-equilibrium measurements are reported for aqueous solutions of various mono- and disaccharides with and without 2:1 valent salts. The spectra reveal a variety of relaxation regimes with relaxation times between 1 micros and 10 ps. In addition, the time-resolved observations enable the study of the mutarotation with relaxation times on the order of 10(3) s. Variation of the concentration and temperature as well as a careful choice of the saccharides allow a discussion of the relaxation processes in terms of a chair-chair ring inversion, two modes of pseudorotation, an exocyclic hydroxymethyl group rotation, a carbohydrate-carbohydrate association, and, in the disaccharide solutions, a rotation of the rings relative to another. Salt-containing solutions show also relaxation phenomena reflecting different steps cation-carbohydrate association and variations in the carbohydrate conformational isomerizations and associations due to interactions with cations.
Behrends
Ralph
R
Third Physical Institute, Georg-August-University, Bürgerstr. 42-44, 37073 Göttingen, Germany.
Kaatze
Udo
U
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry*; D007700:Kinetics; D012996:Solutions; D014867:Water
D002241:Carbohydrates; D012996:Solutions; D014867:Water