| Summary: | Superficially similar carbohydrate polymers from similar sources can have dramatically different characteristics. This work seeks to examine the molecular properties responsible for these differences. Protons responsible for cross-polarization in the anomeric region of Acacia nilotica (AN) were replaced easily by deuterium, but not for Acacia modesta (AM). Time constants describing the mobility and cross-polarization transfer were both found to be lower for AM. Variable contact time experiments showed poorer fits and more heterogeneity for AN. Solution state HSQC experiments showed a lower number of environments in the anomeric region for AM. The relaxation time T2 of AM solutions had a lower value consistent with a higher viscosity. The Tg′ of solutions were −14.5 °C AN and −18.5 °C AM. These results form a largely self-consistent picture of molecular differences between AN and AM, suggesting a more compact but heterogeneous structure for AN and more branching in the case of AM.
|
|---|