Table 4.

Contribution of PTHR Glu⁻³, Glu⁻⁵ and Glu⁻⁶ to the Affinity for PDZ1 or PDZ2^a

PDZ	Sequence	n	KD (μM)	ΔH° (kcal/mol)	TΔS° (kcal/mol)	ΔG° (kcal/mol)
PDZ1	QEEWETVM	1.11 ± 0.01	11.7 ± 0.8	−10.6 ± 0.2	−3.9 ± 0.1	−6.7 ± 0.2
	QAEWETVM	1.10 ± 0.04	13.1 ± 1.7	−4.3 ± 0.3	2.4 ± 0.2	−6.7 ± 0.2
	QEAWETVM	1.21 ± 0.01	25.5 ± 1.1	−7.6 ± 0.1	−1.3 ± 0.2	−6.3 ± 0.3
	QAAWETVM	1.26 ± 0.05	24.4 ± 0.6	−3.80 ± 0.2	2.5 ± 0.2	−6.3 ± 0.3
	QEEWATVM	1.15 ± 0.02	34.2 ± 0.5	−8.5 ± 0.2	−2.5 ± 0.3	−6.1 ± 0.4
	QEAWATVM	1.12 ± 0.03	ns	ns	ns	ns
PDZ2	QEEWETVM	1.13 ± 0.01	9.7 ± 1.1	−21.6 ± 0.3	−14.7 ± 0.5	−6.9 ± 0.4
	QAEWETVM	1.12 ± 0.03	18.1 ± 2.4	−8.1 ± 0.3	−1.6 ± 0.1	−6.5 ± 0.3
	QEAWETVM	0.98 ± 0.02	26.8 ± 2.1	−10.3 ± 0.2	−4.1 ± 0.3	−6.3 ± 0.4
	QAAWETVM	1.26 ± 0.04	57.8 ± 2.	−7.2 ± 0.4	−1.4 ± 0.3	−5.8 ± 0.5
	QEEWATVM	0.88 ± 0.02	35.5 ± 2.0	−8.6 ± 0.3	−2.5 ± 0.1	−6.1 ± 0.2
	QEAWATVM	1.04 ± 0.02	ns	ns	ns	ns

^aaffinity of [PTHRct-8-PDZ] complex determined by ITC. The n, K_D, ΔH°, TΔS°, and ΔG° values represent the mean ± S.E.M. (n = 3)

ns – no significant binding