Table 5.
Estimates of rate constants from fitting Scheme 3 to data from 100 nm ACh patches
| Rate | Wild-type (n = 5) | εL78P (n = 5) | ||
|---|---|---|---|---|
| α2 (s−1) | 1800 | ± 13% | 1040 | ± 20% |
| β2 (s−1) | 53300 | ± 18% | 74600 | ± 9% |
| E2 | 29.1 | ± 7% | 82.2 | ± 17% |
| α1a (s−1) | 3710 | ± 16% | 4930 | ± 11% |
| β1a (s−1) | 127 | ± 64% | 735 | ± 25% |
| E1a | 0.040 | ± 67% | 0.016 | ± 26% |
| α1b (s−1) | 60900 | ± 21% | 226000 | ± 16% |
| β1b (s−1) | 554 | ± 79% | 4630 | ± 45% |
| E1b | 0.026 | ± 94% | 0.018 | ± 45% |
| k+a (μM−1 s−1) | 996 | ± 40% | 62.9 | ± 48% |
| k-a (s−1) | 11800 | ± 27% | 2760 | ± 20% |
| Ka(μM) | 11.8 | ± 27% | 5120 | ± 96% |
| k+b* (μM−1 s−1) | 100 | 100 | ||
| k−b (s−1) | 3070 | ± 77% | 73.8 | ± 20% |
| Kb(μM) | 30.7 | ± 77% | 0.738 | ± 20% |
| k−a+k-b (s−1) | 14900 | ± 10% | 2840 | ± 20% |
| αD (s−1) | 8720 | ± 56% | 3830 | ± 35% |
| βD (s−1) | 96.5 | ± 35% | 15.7 | ± 32% |
| ED =βD/αD | 0.11 | ± 97% | 0.006 | ± 32% |
The assumption of independence of the two binding sites (see Methods) means that k−2a =k−1a, k−2b =k−1b, k+2b =k+1b, k+2a =k+1a, so the numerical subscript is unnecessary and the rate and constants for a and b sites are denoted simply as k−a, k−b, k+a, and k+b. The asterisk denotes rates that were fixed during the fitting. The total dissociation rate from diliganded receptors, k−a+k−b is given in the table. Note that equilibrium constants were calculated separately for each experiment and then averaged. Therefore the values given differ from the ratios of the mean rate constants, especially when the scatter is large.