Soluble Expression and Characterization of Biologically Active Bacillus anthracis Protective Antigen in Escherichia coli

Figure 7

Trypsin digestion and native-PAGE analysis. (a) 5 μg of PA was digested with 5 ng of trypsin for 30 minutes at room temperature and loaded onto 12% SDS-PAGE. 1, protein molecular weight marker; 2, 83 kDa recombinant PA; 3, trypsin digested PA showing two fragments 63 kDa and 20 kDa, respectively. Note that the 20 kDa fragment is around 33 kDa owing to the extra sequences at N-terminal end from the expression vector pET32c. (b) 2 μg of trypsin digested PA was incubated with 2 μg LF at room temperature for 30 minutes and electrophoresed on 4% native-PAGE. 4, PA; 5, LF; 6, PA-LF toxin complex.

(a)

(b)