Figure 2.

Oxidoreductase site in wt-RcMf crystallized without the second substrate dioxygen after 3 min exposure to the iron substrate (Mohr’s salt). Four Fe²⁺ ions (represented by green spheres) are clearly seen bound to the enzyme site. The anomalous difference map obtained from data collected at the Fe K edge is superimposed (copper wire). The four sites are coincident with those found after 15 min of iron free diffusion under aerobic conditions (Fig. 1 ▶, time 15).