Table 1: Ion selectivity of OmpF (WT and mutants) in KCl and CaCl2.

OmpF channel Δ 𝑞 * RP (mV)
1/0.1 M KCl
RP (mV)
1/0.1 M CaCl2
Selectivity inversion

WT0 2 5 . 4 ± 0 . 8 2 2 . 1 ± 0 . 7 Yes
CC+2 2 3 . 8 ± 0 . 8 3 0 . 1 ± 1 . 1 Yes
RR+4 3 1 . 9 ± 1 . 0 3 5 . 4 ± 1 . 7 No

* Δq: effective charge compared to WT OmpF.