# pH_i H_i(mM) openProbability (from Henderson et al (1994) Biochem J 297:615-624, taken from Crampin & Smith (2006) Biophys J 90)
6.0      1e-3 0.05
6.5  3.162e-4 0.3
7.0      1e-4 0.7
7.5  3.162e-5 2.15
8.0      1e-5 3.2