FIGURE 3.

IcaB_Ad^{23–280Δloop} active site and metal-dependent activity. A, the active site of IcaB_Ad^{23–280Δloop} is shown in stick representation with the canonical CE4 motif residues, binding groove residues, and the Zn²⁺ ion colored blue, magenta, and dark gray, respectively. B, metal coordinating triad of IcaB_Ad^{23–280Δloop} shown in stick representation (blue) with the anomalous difference maps above (magenta) and below (green) the Zn²⁺ absorption edge shown as a mesh and contoured at 2.0σ. C, fluorescamine de-N-acetylation activity assay comparison of IcaB_Ad^{23–280Δloop} (as isolated) and incubated with various divalent metal chlorides or metal chelators. DPA, dipicolinic acid. Bars represent triplicate experiments with S.D.