Conformational flexibility of soluble cellulose oligomers: chain length and temperature dependence.

Structures, dynamics, and stabilities of different sized cellulosic oligomers need to be considered when designing enzymatic cocktails for the conversion of biomass to biofuels since they can be both productive substrates and inhibitors of the overall process. In the present work, the conformational variability, hydrogen bonding, and mechanical properties of short, soluble cellulose chains are investigated as a function of chain length. Cellulose oligomers consisting 2, 4, and 6 β-d-glucose units are examined in explicit solvent using replica exchange molecular dynamics (REMD) which provides a rigorous evaluation of the relative stabilities of different conformations and their temperature dependencies. This application of REMD to oligosaccharides in solution also allows evaluation of the quality of the force-field and its suitability for sampling carbohydrates efficiently. Simulation results are analyzed in synergy with polymer theory and compared to known measurements of oligomers and crystals. As the ch...