Figure 2.

Application of the OCAC (oligomeric characterization by the addition of charge) method to the EutN shell protein. (A) Diagram of primary structure of EutN before and after cleavage with TEV protease. The plus symbol “ + ” denotes one additional positive charge. (B) For an n-oligomer, n + 1 possible charge states exist. Shown are the six possible charge-states of a pentamer. (C) EutN OCAC native gel. The engineered EutN(+) oligomer was incubated with TEV protease for 15 min, quenched with iodoacetamide, and then run on a native gel. From left to right, TEV protease concentrations are 0.0, 0.002, 0.01, 0.02, 0.1, and 0.5 mg/mL. The presence of six distinct bands shows that EutN is a pentamer. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]