Table 1.
Peptide | kon | koff | Kd | IC50 (95% C.I.) | rINad |
---|---|---|---|---|---|
µM−1•min−1 | min−1 | µM | µM | % | |
ddKIIIA | 0.75 ± 0.015 | 0.01 ± 0.0015 | 0.013 ± 0.002 | N.A.b | 5 ± 1.1 |
ddKIIIA[K7A] | 0.69 ± 0.11 | 0.13 ± 0.03 | 0.19 ± 0.05 | 0.21 (0.17 – 0.25) | 24 ± 2.1 |
ddKIIIA[K7D] | 0.08 ± 0.005 | 0.083 ± 0.02 | 1.04 ± 0.26 | 1 (0.85 – 1.2) | 5 ± 2.4 |
ddKIIIA[K7S] | 0.77 ± 0.07 | 0.11 ± 0.02 | 0.14 ± 0.03 | 0.31 (0.26 – 0.37) | 29 ± 1.7 |
ddKIIIA[K7F] | 0.55 ± 0.05 | 0.3 ± 0.04 | 0.55 ± 0.09 | 0.6 (0.52 – 0.7) | 6 ± 2.0 |
ddKIIIA[K7G] | 1.2 ± 0.1 | 0.67 ± 0.11 | 0.56 ± 0.1 | 0.47 (0.36 – 0.6) | 29 ± 2.6 |
ddKIIIA[K7L] | 0.39 ± 0.15 | 0.2 ± 0.009 | 0.51 ± 0.2 | 0.87 (0.76 – 1.0) | 7 ± 1.7 |
ddKIIIA[K7V] | 0.33 ± 0.018 | 0.091 ± 0.014 | 0.28 ± 0.045 | 0.34 (0.3 – 0.38) | 14 ± 1.4 |
ddKIIIA[K7T] | 0.1 ± 0.015 | 0.09 ± 0.006 | 0.9 ± 0.15 | 2.3 (1.8 – 3.0) | 19 ± 3.3 |
ddKIIIA[K7dap] | 1.2 ± 0.06 | 0.06 ± 0.008 | 0.05 ± 0.007 | 0.13 (0.09 – 0.19) | 18 ± 1.3 |
KIIIAb | 0.3 ± 0.03 | 0.0016 ± 0.0016 | 0.0053 ± 0.005 | N.A.c | 5 ± 3 |
KIIIA[K7A]b | 0.13 ± 0.006 | 0.015 ± 0.005 | 0.115 ± 0.038 | N.A.c | 23 ± 1 |
KIIIA[K7D] | 0.02 ± 0.002 | 0.008 ± 0.001 | 0.4 ± 0.06 | N.A.c | 6 ± 2.0 |
Rate constants were determined as described under Materials and Methods. Steady-state IC50 and rINa values were obtained with data and equation presented in Fig. 2. Standard deviation and 95% Confidence Intervals (95% C.I.) were calculated from at least three independent experiments using Prism software. For comparison, also shown are data for KIIIA and KIIIA[K7A] from ref. (18).
Data from ref. (18).
IC50 value was not obtained, because the rates of block using peptide concentrations in the range of the expected IC50 were too slow to provide accurate steady-state levels of block within the time frame of the experiments.
rINa for ddKIIIA, KIIIA, and KIIIA[K7A] were directly measured using a saturating peptide concentration, and those for the remaining peptides represent the plateaus of the best-fit curves as described in Fig. 2.