TABLE 2.

Comparison of the stability and binding affinity of PDZ2²⁴⁰, PDZ2²⁷⁰, and PDZ2CT

PDZ2 variant	Kd binding to C-CFTR70	ΔΔGbinding	Kd binding to NHERF1-CT	ΔΔGbinding	M (urea denaturation)	Cma	ΔGb	ΔΔGn-u0
	μm	kcal mol−1	μm	kcal mol−1	kcal mol−1m−1	m	kcal mol−1	kcal mol−1
PDZ2240	4.800 ± 0.300	0	803 ± 64	0	0.42 ± 0.20	1.9 ± 0.2	1.0 ± 0.1
PDZ2270	0.267 ± 0.011	−1.71	93.4 ± 5.9	−1.28	0.83 ± 0.05	3.9 ± 0.1	3.4 ± 0.1	2.4
PDZ2CT	5.300 ± 0.200	0.06	1230 ± 186	0.25	0.91 ± 0.13	4.2 ± 0.1	4.3 ± 0.2	3.3
PDZ2CT·FERM	0.202 ± 0.003	−1.88
PDZ2270(R153Q)	0.930 ± 0.045

^a Cm is the urea concentration at which the protein is 50% unfolded.

^b The free energies have been extrapolated to 0 m urea.