Fig 5.

B204 β2-β3 and β4-α3 loops and Zn²⁺-binding site. (a) Zn²⁺-binding site of B204 and its proximity to the β2-β3 and β4-α3 loops. A structure with ordered β2-β3 and β4-α3 loops and a bound Zn²⁺ ion is shown in cyan, and a structure with no metal ion and disordered loops is shown in light gray. (b) Zn²⁺-binding site coordinated by D39, H41, B73, and H108. A B204 chain with a bound Zn²⁺ ion is shown in cyan, and a chain with no Zn²⁺ ion is in light gray. The dissociation of the Zn²⁺ ion is linked with a 90° flip of H41.