Figure 2.

Cleavage signals of OmpG^casp generated by casp-7. (a) A schematic of caspase detection by OmpG^casp nanopore. (b) Representative current recording trace and (c) the events amplitude histogram of OmpG^2HD before and after adding casp-7. (d) Representative single-channel recording trace and (e) the corresponding all-events histogram of OmpG^casp before and after adding casp-7. The postcleavage event is highlighted in blue, and the casp-7-OmpG interaction is in red. The histogram was fitted with a Gaussian function to derive the current amplitude. The average current was calculated from at least four individual pores, and the errors represent the SD. The percentage of the current was normalized against the current amplitude of the precleaved OmpG^casp pore that was set as 100%. (f) SDS-PAGE analysis of cleaved OmpG^casp by casp-7. Gel analysis by ImageJ showed that 95% of OmpG^casp was cleaved by casp-7. (g) The representative current recording and the events amplitude histogram of cleaved OmpG^casp by casp-7. Cleaved OmpG^casp was prepared by incubating OmpG^casp proteins with casp-7 (1:1 mol ratio) for 1 h at 23°C in 150 mM NaCl and 50 mM HEPES buffer (pH 7.5). To see this figure in color, go online.