Table 5.

Rate and equilibrium constant values obtained from the global fit of the Primed model (with two or three binding steps) to three independent single-channel data sets

Rate and equilibrium constants Unit Primed (two binding sites) Rate and equilibrium constants Unit Primed (three binding sites) 
α″2 s−1 174 ± 26% α″3 s−1 176 ± 26% 
β″2 s−1 71,400 ± 11% β″3 s−1 72,200 ± 11% 
α′2 s−1 12,700 ± 3% α′3 s−1 12,700 ± 3% 
β′2 s−1 3,310 ± 28% β′3 s−1 3,430 ± 28% 
α′1 s−1 661 ± 43% α′2 s−1 656 ± 43% 
β′1 s−1 30,600 ± 83% β′2 s−1 57,300 ± 91% 
γ″2 s−1 11,900 ± 30% γ″3 s−1 12,000 ± 31% 
δ″2 s−1 8,070 ± 27% δ″3 s−1 8,330 ± 27% 
γ′2 s−1 2,380 ± 35% γ′3 s−1 2,530 ± 35% 
δ′2 s−1 1,620 ± 31% δ′3 s−1 1,830 ± 27% 
γ′1 s−1 15,200 ± 84% γ′2 s−1 29,300 ± 91% 
δ′1 s−1 22 ± 48% δ′2 s−1 33 ± 34% 
k s−1 105 ± 5% k s−1 83 ± 12% 
k+ M−1 s−1 0.74 × 104 ± 32% k+ M−1 s−1 1.20 × 104 ± 12% 
kf− s−1 299,000 ± 48% kf− s−1 207,000 ± 46% 
kf+ M−1 s−1 3.83 × 109 ± 47% kf+ M−1 s−1 5.36 × 109 ± 49% 
E2 = β″2/α″2  450 ± 17% E3 = β″3/α″3  450 ± 17% 
E2 = β′2/α′2  0.26 ± 26% E3 = β′3/α′3  0.27 ± 26% 
E1 = β′1/α′1  53 ± 73% E2 = β′2/α′2  97 ± 85% 
F2 = δ″2/γ″2  0.71± 16% F3 = δ″3/γ″3  0.72 ± 15% 
F2 = δ′2/γ′2  0.69 ± 10% F3 = δ′3/γ′3  0.76 ± 8% 
F1 = δ′1/γ′1  0.009 ± 89% F2 = δ′2/γ′2  0.013 ± 80% 
KR = k/k+ mM 18 ± 37% KR = k/k+ mM 7.1 ± 11% 
Kf = kf−/kf+ mM 0.21 ± 82% Kf = kf−/kf+ mM 0.14 ± 82% 
Eeff  96 ± 13% Eeff  102 ± 10% 
EC50 mM 1.4 ± 47% EC50 mM 1.4 ± 15% 
nH  1.84 ± 1% nH  2.5 ± 1% 
Rate and equilibrium constants Unit Primed (two binding sites) Rate and equilibrium constants Unit Primed (three binding sites) 
α″2 s−1 174 ± 26% α″3 s−1 176 ± 26% 
β″2 s−1 71,400 ± 11% β″3 s−1 72,200 ± 11% 
α′2 s−1 12,700 ± 3% α′3 s−1 12,700 ± 3% 
β′2 s−1 3,310 ± 28% β′3 s−1 3,430 ± 28% 
α′1 s−1 661 ± 43% α′2 s−1 656 ± 43% 
β′1 s−1 30,600 ± 83% β′2 s−1 57,300 ± 91% 
γ″2 s−1 11,900 ± 30% γ″3 s−1 12,000 ± 31% 
δ″2 s−1 8,070 ± 27% δ″3 s−1 8,330 ± 27% 
γ′2 s−1 2,380 ± 35% γ′3 s−1 2,530 ± 35% 
δ′2 s−1 1,620 ± 31% δ′3 s−1 1,830 ± 27% 
γ′1 s−1 15,200 ± 84% γ′2 s−1 29,300 ± 91% 
δ′1 s−1 22 ± 48% δ′2 s−1 33 ± 34% 
k s−1 105 ± 5% k s−1 83 ± 12% 
k+ M−1 s−1 0.74 × 104 ± 32% k+ M−1 s−1 1.20 × 104 ± 12% 
kf− s−1 299,000 ± 48% kf− s−1 207,000 ± 46% 
kf+ M−1 s−1 3.83 × 109 ± 47% kf+ M−1 s−1 5.36 × 109 ± 49% 
E2 = β″2/α″2  450 ± 17% E3 = β″3/α″3  450 ± 17% 
E2 = β′2/α′2  0.26 ± 26% E3 = β′3/α′3  0.27 ± 26% 
E1 = β′1/α′1  53 ± 73% E2 = β′2/α′2  97 ± 85% 
F2 = δ″2/γ″2  0.71± 16% F3 = δ″3/γ″3  0.72 ± 15% 
F2 = δ′2/γ′2  0.69 ± 10% F3 = δ′3/γ′3  0.76 ± 8% 
F1 = δ′1/γ′1  0.009 ± 89% F2 = δ′2/γ′2  0.013 ± 80% 
KR = k/k+ mM 18 ± 37% KR = k/k+ mM 7.1 ± 11% 
Kf = kf−/kf+ mM 0.21 ± 82% Kf = kf−/kf+ mM 0.14 ± 82% 
Eeff  96 ± 13% Eeff  102 ± 10% 
EC50 mM 1.4 ± 47% EC50 mM 1.4 ± 15% 
nH  1.84 ± 1% nH  2.5 ± 1% 

The fits were constrained by the assumption that the binding sites are equivalent and independent. This constraint was implemented by the following equations: k+1 = k+2 = k+3 = k+ and k−1 = k−2 = k−3 = k. In addition, one rate constant in each cycle was fixed by the constraint of microscopic reversibility (Colquhoun et al., 2004). The equilibrium constants E, F, and K, effective efficacy, Eeff, and the EC50 and Hill slope of the predicted Popen curve were calculated from the rate constants for each set and then averaged. Values are means ± coefficient of variation (i.e., SD of the mean expressed as a percentage of the mean).

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