TABLE 2.
Opening rate constant (ko)
|
Closing rate constant (kc)
|
Equilibrium constant (Keq)
|
|||||
---|---|---|---|---|---|---|---|
Mean | SE | Mean | SE | Mean | SE | Keq ratio | |
Wt | 120 | 1000 | 0.12 | ||||
δS268V | 141 | 19 | 53 | 6 | 2.66 | 0.47 | |
αY277D (24′)+ δS268V | 67 | 8 | 278 | 15 | 0.24 | 0.03 | 0.09 |
αY277L (24′) + δS268V | 138 | 12 | 314 | 35 | 0.44 | 0.06 | 0.17 |
αY277S (24′) + δS268V | 124 | 22 | 428 | 22 | 0.29 | 0.05 | 0.11 |
αY277T (24′) + δS268V | 44 | 3 | 667 | 59 | 0.07 | 0.01 | 0.02 |
αY277H (24′) + δS268V | 51 | 5 | 479 | 19 | 0.11 | 0.01 | 0.04 |
αY277F (24′) | 448 | 47 | 853 | 40 | 0.53 | 0.06 | 4.38 |
αL279T (22′) | 198 | 13 | 446 | 30 | 0.44 | 0.04 | 3.7 |
αL279I (22′) | 120 | 3 | 1005 | 55 | 0.12 | 0.01 | 1 |
αL279W (22′) | 488 | 131 | 26 | 2 | 18.77 | 5.24 | 156.41 |
αF280W (21′) | 180 | 8 | 394 | 15 | 0.46 | 0.03 | 3.81 |
αV283A (18′) | 165 | 11 | 549 | 33 | 0.30 | 0.03 | 2.5 |
αV283W (18′) | 239 | 27 | 187 | 11 | 1.28 | 0.16 | 10.65 |
αV283Q (18′) | 221 | 2 | 245 | 28 | 0.90 | 0.10 | 7.52 |
αI289A (12′) | 89 | 3 | 1019 | 61 | 0.09 | 0.01 | 0.73 |
αI290W (11′) | 151 | 16 | 568 | 108 | 0.27 | 0.06 | 2.22 |
αI290Q (11′) | 91 | 7 | 1599 | 301 | 0.06 | 0.01 | 0.47 |
αI290A (11′) | 87 | 1 | 1945 | 194 | 0.04 | 0.00 | 0.37 |
αV293W (8′) | 89 | 12 | 945 | 51 | 0.09 | 0.01 | 0.78 |
αI294W (7′) | 71 | 9 | 970 | 42 | 0.07 | 0.01 | 0.61 |
αN297W (4′) | 95 | 11 | 1182 | 44 | 0.08 | 0.01 | 0.67 |
αN297M (4′) | 70 | 9 | 897 | 50 | 0.08 | 0.01 | 0.65 |
Rate constants are s−1 (mean of three patches). Keq = ko/kc. The Keq ratio is mutant/wt, except for the Y277 series, which is mutant/δS268V background. No correction was made for channel block by the agonist so the kc values are approximately half of those of unblocked AChRs. Φ-values were not estimated for positions 4′, 7′, and 8′ because the range of Keq values was less than fivefold.