Justus Nwachukwu

Supramolecular Assembly of Redox Proteins to form Nanowires for Ultra-Long-Range Biological Electron Transfer

Justus Nwachukwu, Arizona State University, Graduate Student

Supramolecular Assembly of Redox Proteins to form Nanowires for Ultra-Long-Range Biological Electron Transfer

J. N. Nwachukwu, M. A. Thirmurthy, J. T. Atkinson, M. Y. El-Naggar and A. K. Jones

Exoelectrogenic organisms transfer electrons from their internal quinone pool to extracellular acceptors over nano-scale distances through appendages known as "biological nanowires." These structures have been variously described as cytochrome-rich membrane extensions or pili, and the components and mechanisms of this long-range electron transfer remain largely unknown. In fact, current physical understanding of biological electron transfer is only sufficient to describe electron movement on the nm scale. This presentation will describe a proteinaceous, supramolecular model for ultralong-range biological electron transfer. This supramolecular structure is based on a self-assembling peptide. To facilitate assembly, a small redox protein from Shewanella oneidensis, a model exoelectrogen, is fused to the peptide component which can be combined with free peptide to assemble a fibrillar structure. Assembled nanowires have average dimensions of 500 nm, 15 nm by 9 nm. Electrochemical measurements show the nanowires retain the native reduction potential of their constituent protein, and electrochemical gating results suggest electrical conductivity occurs along the length of these structures via a cytochrome-mediated electron transfer.

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