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Glucose is very soluble in water, but linking multiple glucose residues b(1-4) produces insoluble cellulose oligomers. Solvents that can dissolve cellulose may lead to the development of new packaging or textiles, and may lead to improvements in enzymatic or chemical cellulose hydrolysis. The resulting glucose can be fermented to ethanol as a supplement to fossil fuel supplies, or can be used as food. Computer simulations using molecular dynamics (MD) are particularly useful to study the solution behavior of carbohydrates because they provide detailed information that is difficult or impossible to obtain by experimental methods.

Our objective was to model cellulose oligomers in solution using MD.

The program CHARMM was used to model cellulose oligomers in water, in 3 molal sodium chloride, and in dimethysulfoxide (DMSO).

Results for cellotriose in pure water showed localization of the solvent in specific bands around hydroxyl groups. The glycosidic linkages were not flat as in the cellulose crystal structure. In sodium chloride, the sodium ions were found to localize in some of the same bands as water oxygens, while chloride ions were loosely associated with the cellotriose. In DMSO, the hydroxymethyl groups usually adopted the gg rotamer, which was seen much less frequently in water. Also, the glycosidic torsions in DMSO showed different behavior than in water.

These results suggest that solvents can be highly structured around cellotriose, and the conformation of cellotriose depends on interactions with the surrounding environment. The method developed can be used to examine more complex solvents that are known to dissolve cellulose, providing insight into their mechanisms.