Abstract:  Proteins are remarkably good electronic conductors, if contacted by chemical bonds to electrodes that allow for injection of electrons or holes into their hydrophobic interior. They outperform the best of synthetic "molecular wires" by a large margin. In contrast, hydrated peptides are better insulators than alkane chains. The resolution of this apparent paradox may lie in the different electrostatic contributions of water molecules to fluctuations in the exterior and interior of the protein.  In the interior, hopping times may be shorter that electrostatic relaxation times, minimizing losses to reorganization.  This phenomenon leads to important applications.  Electronic circuits can be self-assembled from protein components and the fluctuations of enzymes can be followed directly from fluctuations in their conductance, as illustrated by the signals generated by a 'wired' DNA polymerase.