An alternative explanation for the collapse of unfolded proteins in an aqueous mixture of urea and guanidinium chloride

- A mixture of urea and GdmCl stabilizes a compact-denatured conformation.
- The latter is stabilized by an increase in solvent-excluded volume effect.
- The magnitude of the latter depends upon the aqueous solution density.
- The 4 M urea + 4 M GdmCl density causes collapse of unfolded conformations.