Shape of the cellodextrins in aqueous solution at 25 °C

Diffusion coefficients and intrinsic viscosities of the cellodextrins, cellobiose to cellohexaose, were measured in aqueous solution at 25 °C. Axial ratios of the oligomers were computed by the Stokes–Einstein diffusion equation modified for non-spherical particles by Perrin's theory, and by the Einstein–Simha viscosity equation. The hydrodynamically calculated axial ratios were equal to the corresponding axial ratios determined from fully extended Stuart–Briegleb models after allowances were made for hydration. Thus the cellodextrins appear to be rodlike and give no indication of pronounced flexibility or folding in aqueous solution at 25 °C.