Computational approach to study electron-transfer proteins: Azurin for bio-molecular devices Original Research Article

We outline an efficient approach, based on the interplay between ab-initio methods and continuum modeling, to the study of Azurin. We focus our investigation on issues relevant for the exploitation of Azurin in bio-molecular electronics. (i) The attachment of the macromolecule to a metal surface, through a cysteine residue present on its periphery, is tackled by means of atomistic DFT calculations. The electronic properties of the hybrid cysteine/gold interface reveal chemical bonding. (ii) Electron transfer through the redox-active Cu site is investigated by both atomistic and atomistic/continuum calculations. The atomistic treatment unravels the electronic properties at the active site in the two switchable oxidation states, and gives the electronic couplings for the electron transfer rate. The atomistic/continuum treatment enables the computation of the reorganization energy in different environments, i.e. the effects of the nuclear degrees of freedom in electron transfer.