Purity and oligomeric state of STNhaA. (a) IMAC-purified STNhaA probed by SDS-PAGE analysis, Western-immunoblot and BN-PAGE.

<p>Shown is the silver-stained gel (12% Bis/Tris gel) after electrophoretic separation of 200 ng of STNhaA (left panel, left lane). Molecular masses of co-separated standard proteins are indicated in kDa. NhaA (33 kDa) and its SDS-resistant oligomer (53 kDa) were positively probed in Western-immunoblot with anti-His-tag antibodies (left panel, right lane). Coomassie-stained gel (4–16% Bis/Tris gel) after BN-PAGE analysis of 7 µg of IMAC purified STNhaA (right panel). The molecular masses of co-separated standard proteins are indicated on the left in kDa. (b) Chromatogram of SEC-MALLS analysis of β-DDM solubilized STNhaA. 80 µg of IMAC-purified STNhaA were applied to size-exclusion chromatography on a Superdex 200 column. The chromatogram shows detector readings of the 90 light scattering detector, the UV₂₈₀ detector, and the refractive index detector in black, dark gray and light gray, respectively. The horizontal black lines indicate the calculated mass of STNhaA, detergent micelle, STNhaA/detergent complex and indicate a high degree of monodispersity throughout the elution peak.