FIGURE 9.

Hemolytic and cAMP-inducing activities of the various CyaA preparations. The different CyaA samples (i.e. CyaA renatured by G25 buffer exchange in the presence of calcium (black diamonds), CyaA renatured by G25 buffer exchange in the absence of calcium (open diamonds), and the oligomeric (black squares) and monomeric (black circles) CyaA species collected after refolding on TSK column in the presence of calcium (see the O and M fractions in Fig. 5C)) were directly diluted into an erythrocyte suspension (5 × 10⁸ cells/ml in buffer B) to reach the indicated final concentrations. All hemolysis (A) and cAMP production experiments (B) were performed in the presence of 2 mm calcium except for the G25 buffer-exchanged CyaA in the absence of calcium, which was tested in the presence of 4 mm EDTA. The hemolytic activity and intracellular cAMP accumulation were determined as described under “Experimental Procedures.” Error bars, S.D.