Figure 2.

Conductance trace of the S272A mutant of OmpF porin. Recording was obtained at +143 mV as described in Materials and Methods and previously (3). At the center of the trace, the cooperative activation of a trimer and its inactivation in three single steps is seen. The channel characteristics are qualitatively similar to those of wild-type OmpF porin, while quantitatively, small, yet distinct, differences exist (Table 1).