TABLE 3.

Thermodynamic stabilities and thermal unfolding temperatures

Variant	ΔGua	mb	Cmidc	Tmd
	kcal/mol	kcal mol−1 m−1	m
WT	3.0 ± 0.1	1.4 ± 0.01	2.2 ± 0.04	40°C
W70A	NDe			ND
W70L	ND			ND
W70F	2.4 ± 0.1	1.4 ± 0.03	1.7 ± 0.04	34°C
W70Y	2.0 ± 0.1	1.3 ± 0.03	1.5 ± 0.04	30°C

^a ΔG_u is apparent change in free energy of unfolding as extrapolated to zero denaturant concentration by a two-state model.

^b The m value represents the slope d(ΔG_u)/d(M) and correlates with extent of nonpolar surfaces exposed on denaturation.

^c C_mid is defined as the denaturant concentration at which 50% of the protein is unfolded.

^d T_m is the apparent midpoint unfolding temperature of the free domains.

^e ND means not defined as these values could not be determined due to absence of a pre-transition state and noncooperative transition.