PNNL

Abstract

Molecular dynamics simulations were used to investigate the internal conformational dynamics and solvation properties of the three natural cyclodextrins, a-, ß-, and ?-cyclodextrin, in aqueous solution at room temperature. These glucose-derived oligosacharides present a molecular structure that confers them the ability to complex host molecules and change their physico-chemical properties. The structural behavior of cyclodextrins in solution is crucial for their complexation abilities. Analyses of the obtained trajectories show that inter-glucose secondary hydrogen bonds are present in solution, but show a very dynamical character where alternative hydrogen bonds to water molecules can be formed. Despite of the lower hydrophilicity of the cyclodextrins inner-cavities, they were found to be solvated and the number of water molecules inside of the cavity roughly doubles per glucose unit added to the ring. The residence times for water molecules inside of the cavities are inversely proportional to the cavity size.