Figure 1.
The effect of urea and sorbitol on HPC osmotic stress force curves at 20 °C. The PEG osmotic pressure dependence of the spacing between HPC chains determined from the Bragg scattering peak is shown for HPC in water, in 0.5 and 1 m urea, and in 0.5 and 1 m sorbitol. Urea has no effect on HPC forces, while intermolecular spacings are significantly closer in sorbitol at the same PEG osmotic pressure. The arrow illustrates the apparent excess osmotic pressure, Πexcess, exerted by 1 m sorbitol at ~ 15.5 Å.