Table 2.
Kinetic parameters of the truncated VhChiP titrated with the synthesized N-plug peptide
| VhChiP | Sugar | N-plug | kon × 106 (M−1s−1) | τc (ms) | koff × 103 (s−1) | K (M−1) |
|---|---|---|---|---|---|---|
| WT | cis | - | 68 ± 1.4 | 3.7 ± 0.4 | 0.27 ± 0.4 | 250,000 ± 50,000 |
| trans | - | 50 ± 1.2 | 4.7 ± 0.5 | 0.21 ± 0.5 | 240,000 ± 70,000 | |
| Truncated | cis | - | 5.6 ± 0.3 | 2.0 ± 0.3 | 0.50 ± 0.1 | 11,000 ± 3000 |
| trans | - | 6.8 ± 0.5 | 3.3 ± 0.5 | 0.30 ± 0.1 | 23,000 ± 5000 | |
| Truncated | cis | trans | 56 ± 0.1 | 4.5 ± 1.0 | 0.22 ± 0.01 | 255,000 ± 10,000 |
| cis | cis | - | - | - | n.d. |
The equilibrium binding constant (K, M−1) is estimated from Equation 1, which is derived from the relative reduction of the average single channel conductance when the channel was titrated with different concentrations of chitohexaose. The on-rate (kon, M−1 s−1) is given by kon = K · koff and the off-rate (koff, s−1) for the single trimeric molecule of VhChiP channel and its mutant by titration with chitohexaose from the relationship koff = 1/τc.
n.d., nondetectable blocking events.