Figure 2

EF-hand motif 1 of EhCaBP1 showing the heavy-metal coordination. (A) Calcium coordination in the calcium binding loop-1 of EhCaBP1. Calcium coordinates with seven of its ligands including one water molecule to satisfy the coordination geometry. The coordination distances are shown. (B) Lead coordination in the calcium binding loop-1 of EhCaBP1. Lead co-ordinates with six ligands in the EF-hand motifs. The coordination distances between the Pb²⁺ and ligand oxygen atoms for EF-hand 1 motif range between 2.1 Ǻ and 2.8 Ǻ. (C) Strontium coordination in the calcium binding loop-1 of EhCaBP1. Strontium co-ordinates with seven ligands in the EF-hand motif. The coordination of Sr²⁺ is similar to that of Ca²⁺ coordination except for the absence of water molecule in the coordination. The 3^rd aspartate residue is donating both of its oxygen ligands to satisfy the coordination geometry. The coordination distances between the ion and oxygen atom for the EF-hand 1 motif range between 2.1 Ǻ and 2.8 Ǻ. (D) Barium coordination in the calcium binding loop-1 of EhCaBP1. Barium coordinates with seven ligands including one water molecule to satisfy the coordination geometry. The coordination distances are shown. The coordination of Ba²⁺ is similar to that of Ca²⁺. The coordination distances between the ion and oxygen atom for EF-hand 1 motif range between 2.4 Ǻ and 2.9 Ǻ.