Polysaccharides are large, abundant biomolecules, composed of carbohydrates that are linked together via glycosidic bonds. Water-solube polysaccharides are used as viscosity enhancers, gelling agents, emulsion and suspension stabilizers, and water retention agents in a wide range of food and consumer products. The molecular dynamics and conformations of polysaccharide chains in solution are still a challenging area of investigation. One approach to studying the molecular behavior of polysaccharides with low degree of polymerization is with the help of molecular dynamics simulations (MD) using all-atom (AA) force fields (FF) that have been explicitly parameterized for such polymers. However, as different AA FF have been parameterized in different ways and keeping different properties in mind, the properties predicted by these models could differ from one another. And since the reliability of MD-based approaches rely fundamentally on the quality of potentials that mimic the various bonded and non-bonded interactions, it is necessary to validate these FF parameters. In this work, we have compared the performance of the widely used CHARMM, GLYCAM and OPLS-AA FFs for three linear polysaccharides, namely, amylose, dextran, and pullulan. Specifically, MD simulations were carried out for 100 ns at 298 K, 313 K, and 333 K, and the simulation trajectories were analyzed to study polysaccharide conformations as well as the structure of water at the polysaccharide-water interface. All properties obtained using simulations were further compared with our experimental observations.

Comparison of different atomistic force fields for the study of polysaccharide chain conformations in water

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