(a) Conformer 1 for which His-6, His-13, His-14 residues are coordinated to copper ions. (b) Conformer 2 for which Asp-1 (green), His-6 (blue), His-14 (blue) residues are coordinated to a copper ion. (c) Conformer 3 for which Asp-1 (green), His-6 (blue), His-14 (blue) residues are coordinated to a copper ion and Asp-1 (green), His-14 (blue), Val-40 (black) are coordinated to another copper ion. (d) Conformer 4 for which Asp-1 (green), His-6 (blue), His-14 (blue) residues are coordinated to a copper ion and Asp-1 (green), His-13 (blue), Val-40 (black) are coordinated to another copper ion. The magnified coordination geometries are shown in Fig. S6 in SI.