FIG. 4.

Formaldehyde treatment of purified M. jannaschii CorA-PPD indicates a homotetramer. The M. jannaschii CorA-PPD protein was purified and subjected to formaldehyde treatment as described in Materials and Methods and the legend to Fig. 2. The resulting gel was scanned into Canvas. No editing was performed except adjustment of brightness and contrast. Additional experiments at different protein or formaldehyde concentrations or different times of exposure to formaldehyde give similar results. Boiling of the samples before electrophoresis regenerated a significant amount of the monomer band as expected (data not shown). In the experiment shown, formaldehyde treatment was performed in the absence (left lane) or presence (right lane) of the selective CorA inhibitor, Co(III)hexaammine (12).