Figure 1.

Location of the His₃ sites as designed in the closed structure of MBP [PDB ID code 1anf (34)]. The two domains (Domain I, yellow; Domain II, blue) of MBP are connected by a β-strand hinge (green). The positioning of the zinc atom is the same for the A1 and A2 sites (red), and is located within the original maltose-binding pocket, near the hinge. The zinc centers for the B1 (orange) and B2 (pink) sites are located outside of the original maltose-binding pocket. Relative to the plane of the figure, the B2 site is closest to the viewer, followed by the B1 site and then the A sites. The large blue sphere represents the attachment position of the fluorophore IANBD at D95C. Detailed description of designs available in the supplemental data, which is published on the PNAS web site, www.pnas.org.