Figure 6. A schematic of two-state energy level diagram depicting the thermodynamic and mechanical stabilization of M-crystallin upon Ca²⁺ binding.

Ligand binding not only stabilizes the native state (N) by ΔG∼11.4 kcal/mol but also reduces the unfolding potential width (Δx_u) from 0.55 nm to 0.38 nm. Estimates of unfolding transition state (TS) energy barriers (ΔG^‡) are also indicated. See text and Tables 1 and 2 for more details.