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Table 1
Main properties of the wild type (LESWAS) and mutant (LASWAS and LEDWAS) NaChBac bacterial channels generated and used for the present patch-clamp study. Here Qf stands for the nominal fixed charge at the selectivity filter and IC50 is the [Ca] threshold value providing 50% blockade of the Na+ current. Qualitative properties (selectivity and AMFE) are marked as “+” where present and “−” where absent.
| Channel | SF amino acid sequence | Nominal Qf/e | Ca2+/Na selectivity | Divalent blockade, AMFE |
|---|---|---|---|---|
| Zero-charge mutant | LASWAS | 0 | – | – |
| NaChBac wild-type | LESWAS | −4 | + (Na > Ca) | – |
| Added-charge mutant | LEDWAS | −8 | + (Ca > Na) | + (IC50 = 5 μM) |