Our results indicate that the environment can have a sizeable effect on the preferred cluster and type of coordination. Nevertheless, the exposure of the metal centers can vary depending on the placement inside the protein chain. We expect quantitative differences between metal centers exposed to the solvent and those buried in a "protein" environment. This effect can be reproduced by tuning the dielectric constant of the solvent in DFT calculations (see Methods). We have performed calculations with dielectric constants of ε = 78, representing a metal center totally exposed to solvent. To obtain information on buried metal centers, we have performed single-point calculations with different dielectric constants. To reproduce the different exposures to the solvent, we have followed the work performed by Dudev and Lim . To reproduce the conditions of systems buried in "protein" environment, we selected a dielectric constant of ε = 2, whereas, for an intermediate case, we choose a dielectric constant of ε = 4.