TABLE 2.

Thermal unfolding parameters

Variant	pH °C	kcal mol−1	ΔHTm kcal mol−1 K−1	ΔCP °C	Tx† kcal mol−1	ΔGTx‡
Wild-type	6.0	68.9 ± 0.1¶	141 ± 2	3.9 ± 0.1	34.6 ± 0.1	7.2± 0.1
	6.5	67.9 ± 0.1	147 ± 2	32.3 ± 0.1	7.8 ± 0.3
	7.0	67.0 ± 0.2	140 ± 3	32.9 ± 0.1	7.2 ± 0.1
	7.5	66.5 ± 0.1	163 ± 3	27.2 ± 0.1	9.6 ± 0.1
	8.0	65.1 ± 0.2	133 ± 3	32.7 ± 0.1	6.5 ± 0.2
S-126C	6.0	69.3 ± 0.1	157 ± 9	4.0 ± 0.1	32.2 ± 0.1	8.7 ± 0.9
	6.5	69.2 ± 0.1	144 ± 4	35.1 ± 0.1	7.3 ± 0.5
	7.0	68.7 ± 0.1	148 ± 5	33.4 ± 0.1	7.8 ± 0.3
	7.5	67.0 ± 0.1	139 ± 4	33.9 ± 0.1	6.9 ± 0.2
	8.0	66.4 ± 0.2	137 ± 2	33.7 ± 0.1	6.7 ± 0.3
S-265C	6.0	63.1 ± 0.1	112 ± 5	3.3 ± 0.1	36.1 ± 0.1	4.6 ± 0.4
	6.5	62.7 ± 0.1	110 ± 4	36.4 ± 0.1	4.4 ± 0.2
	7.0	61.5 ± 0.2	109 ± 4	35.3 ± 0.1	4.3 ± 0.1
	7.5	60.1 ± 0.1	108 ± 3	34.1 ± 0.1	4.2 ± 0.1
	8.0	59.1 ± 0.1	104 ± 3	33.9 ± 0.1	4.0 ± 0.3
S-126/265C	6.0	64.6 ± 0.1	127 ± 7	2.9 ± 0.1	23.4 ± 0.1	7.9 ± 0.2
	6.5	63.8 ± 0.1	112 ± 5	26.0 ± 0.1	6.7 ± 0.1
	7.0	62.7 ± 0.3	101 ± 6	29.5 ± 0.1	5.1 ± 0.2
	7.5	62.1 ± 0.1	95.6 ± 1	30.7 ± 0.1	4.6 ± 0.3
	8.0	60.3 ± 0.3	93 ± 3	29.8 ± 0.1	4.3 ± 0.1

Eqs. 1 and 2 were fit to the data shown in Fig. 2.

Temperature of melting (ΔG_Tm = 0).

^†Temperature of maximal stability.

^¶Maximal stability.

^‡Standard deviations were calculated by splitting the data into three sets of equal size and performing three independent fits for each variant.