Table 1. EC50, ΔΔG, efficacy for GLPG1837, and relaxation time constants for the addition and removal of VX-770 for mutations in the five predicted binding sites
EC50 (μM)ΔΔG (kJ/mol)Efficacy (% increase)τon (VX-770) (s)τoff (VX-770) (s)
WT0.26 ± 0.04115 ± 76.7 ± 1.2361 ± 39
G551D2.19 ± 0.334,115 ± 7145.9 ± 2.468 ± 14
Site I
D924A>3<−6.06
D924E0.71 ± 0.07−2.49194 ± 8
D924N2.29 ± 0.78−5.39464 ± 7378 ± 18115 ± 7
N1138F/G551D0.16 ± 0.056.48666 ± 131
N1138L/G551D0.08 ± 0.028.20253 ± 3218 ± 5268 ± 25
N1138Y/G551D0.40 ± 0.104.211,106 ± 279
S1141K/G551D0.26 ± 0.025.281,326 ± 16114 ± 6221 ± 50
S1141R/G551D0.51 ± 0.133.612,868 ± 479
S1141T/G551D1.74 ± 0.310.572,167 ± 329
Site IIN
F229A0.46 ± 0.07−1.41135 ± 266.2 ± 1.3338 ± 49
F236A0.34 ± 0.14-0.6781 ± 1419 ± 8173 ± 45
Y304A>3<−6.06>80 ± 949 ± 1118 ± 6
Y304F2.28 ± 0.34−5.3882 ± 12
Y304T>3<−6.06>101 ± 7
F312A (2 mM ATP)0.40 ± 0.13−1.0726 ± 2
F312A (30 µM ATP)1.30 ± 0.26−3.99105 ± 1215 ± 138 ± 5
F931A1.14 ± 0.26−3.5783 ± 12
Site II
K190A0.08 ± 0.012.9261 ± 12
T360A0.12 ± 0.011.92120 ± 38
S364A0.18 ± 0.01−0.91126 ± 5
Site III
Q237A0.92 ± 0.32−3.13615 ± 101
D993A0.36 ± 0.04−0.81283 ± 47
S1149A0.16 ± 0.031.20139 ± 36
Site IV
S182A0.22 ± 0.040.41138 ± 238.2 ± 1.5343 ± 96
S263A0.27 ± 0.05−0.09148 ± 186.1 ± 1.5288 ± 68

ΔΔG was calculated from the following equation: ΔG(mutant)ΔG(WT)=ΔΔG=RTlnEC50(mutant)EC50(WT).

EC50(WT) was replaced with EC50(G551D) when the mutation was introduced to G551D-CFTR background.