This is Human lactalbumin with the bound calcium ion in cyan and three asp ligands in red. The pdb is here: [Bbk|BNL|ExP|Waw|Hal].

This is human lysozyme with residues that were mutated in order to recruit the calcium binding site coloured red. Note the structural homology. The pdb file is here: [Bbk|BNL|ExP|Waw|Hal].

Metal Binding