- Conformational changes of proteins are widely used in nature for controlling cellular functions, including ligand binding, oligomerization, and catalysis. Despite the fact that different proteins and artificial peptides have been utilized as electron-transfer mediators in electronic devices, the unique propensity of proteins to switch between different conformations has not been used as a mechanism to control device properties and performance. Toward this aim, we have designed and prepared new dimeric coiled-coil proteins that adopt different conformations due to parallel or antiparallel relative orientations of their monomers. We show here that controlling the conformation of these proteins attached as monolayers to gold, which dictates the direction and magnitude of the molecular dipole relative to the surface, results in quantitative modulation of the gold work function. Furthermore, charge transport through the proteins as molecular bridges is controlled by the different protein conformations, producing either rectifying or ohmic-like behavior.