FIGURE 7.

AmiC requires metal cations for activity. A, treatment of AmiC-CTD with metal chelators results in nearly complete ablation of activity. The most marked effect was with the zinc-specific chelator 1,10-phenanthroline. B, addition of metal ions rescue AmiC-CTD activity. Following treatment of AmiC-CTD with 1,10-phenanthroline, the chelator was removed by dialysis, and 10 mm metal salts were added to the protein. The addition of ZnCl₂, MgCl₂, and CaCl₂ resulted in 70–80% restoration of protein activity. Error bars represent mean ± S.D. of triplicate reactions. (**, p < 0.01; *, p < 0.05).