Conformation and physical properties of cycloisomaltooligosaccharides in aqueous solution

Abstract

We studied the conformation and physical properties of cyclic and linear isomaltooligosaccharides in aqueous solution by intrinsic viscosity measurement, small angle X-ray scattering (SAXS) and molecular modeling. We used four cycloisomaltooligosaccharide samples (CIs) with degree of polymerization (DP) 7-10 (CI-7-CI-10) and five linear isomaltooligosaccharide samples (LIs) with DP 7-11 (LI-7-LI-11). The values of α in the Mark-Houwink-Sakurada equation [η]=KM(w)(α) for the CI and LI were determined to be 0.50 and 0.78, respectively. The radii of gyration (R(G)) of CI-7, CI-8, CI-9 and CI-10 determined from SAXS data were 6.7, 6.9, 7.5 and 8.3Å, respectively. The scattering profile of CI-9 compared with those obtained for molecular models indicated that CI molecular chains are less flexible than those for LIs and adopt a rather compact circular conformation.

Keywords: Cycloisomaltooligosaccharide; Intrinsic viscosities; Molecular dynamic simulation; Small angle X-ray scattering.