The conformational dynamics of a single enzyme can be monitored in real-time by tethering a single T4 lysozyme, through a single-cysteine residue, to a single-walled carbon nanotube (SWCNT) field effect transistor (FET).  The extraordinary sensitivity of this nanoscale device converts the substrate-induced conformational changes of T4 lysozyme into an electronic readout.  To probe the origin of signal transduction in our device, a number of T4 lysozyme variants were engineered in which positively charged amino acids, K83 and R119, at positions near the single-cysteine attachment site were substituted for either a neutral (alanine) or a negatively charged amino acid (glutamate).  The ability of each charged variant to induce a characteristic gating behavior in the SWCNT-FET device suggests that the interaction of charged amino acids with the carbon nanotube results in the electronic readout of the device.  These findings provide a foundation to further increase the sensitivity of the SWCNT-FET device.

Charged residues of T4 lysozyme gate a single-walled carbon nanotube field-effect transistor

243rd National Meeting (2012)

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