*2.2. Pore-Forming Activity of OM Porin from M. primoryensis KMM 3633T*

The observed pore-forming activity of the total fraction of OM proteins of *M. primoryensis* KMM 3633T was instable; nevertheless, this confirmed the presence of porin among the OM proteins of the bacteria (data not shown). When purified MpOmp was added in small quantities (10–100 ng/mL) to the aqueous solution bathing an artificial lipid bilayer, the membrane conductance increased by several orders of magnitude (Figure 2A,B). The current-voltage characteristic of the porin channel is linear in the range up to 180 mV (Figure 2C). The pore-forming activity of MpOmp was found to depend on the salt concentration in the aqueous phase. We failed to record channel formation at NaCl concentration below 0.2 M. The linear dependence of the current through the porin channel is observed when the salt concentration varied in the range 0.5–2.0 M (Figure 2D).

**Figure 2.** Current traces recorded after the addition of *M. primoryensis* KMM 3633T porin to bilayer lipid membrane (BLM) in the presence of 1.0 M (**A**) and 0.2 M (**B**) NaCl; current-voltage characteristic of MpOmp channel (**C**); the dependence of the current through the MpOmp channel on NaCl concentration (**D**).

BLM formed from a 1% solution of 1-monooleoylglycerol in *n*-heptane. Aqueous phase: 20 mM Tris-HCl, pH 7.4 (buffer A), 0.5–2.0 M NaCl, protein concentration 10–100 ng/mL. Membrane potential is 50 mV.
