Figure 4.

(Top) Naively assuming a linear relationship between folding free energy and urea concentration (eq 1) suggests that the m value (a measure of denaturant strength) for unfolding is strongly dependent on packing density under these crowding conditions. The fitted m value approaches that seen in solution (and in the case of crowding by either always-folded or always-unfolded neighbors, Figure 2); however, the packing density falls low enough that neighboring molecules no longer interact. (Bottom) Similarly, the calculated folding free energy approaches the value seen for dilute surface coverage when the packing density falls below this interaction distance.