Abstract
Proteins have been shown to be electrically-conductive if tethered to an electrode by means of a specific binding agent, allowing single molecules to be wired into an electrical sensing circuit. This development opens the possibility of exploiting the remarkable chemical versatility of enzymes as sensors, detectors and sequencing devices. We have engineered contact points into a Φ29 polymerase by introducing biotinylatable peptide sequences. The modified enzyme was bound to electrodes functionalized with streptavidin. Φ29 connected by one biotinylated contact and a second non-specific contact showed rapid small fluctuations in current when activated. Signals were greatly enhanced with two specific contacts. Features in the distributions of DC conductance increased by a factor 2 or more over the open-to closed conformational transition of the polymerase. Polymerase activity is manifested by rapid (millisecond) large (25% of background) current fluctuations imposed on the DC conductance.
Footnotes
Paper has been shortened and better gel data obtained on the activity of the modified enzyme.