Exploring the electronic and mechanical properties of protein using conducting atomic force microscopy

Zhao, J, Davis, J, Sansom, M and Hung, A 2004, 'Exploring the electronic and mechanical properties of protein using conducting atomic force microscopy', Journal of the American Chemical Society, vol. 126, no. 17, pp. 5601-5601.


Document type: Journal Article
Collection: Journal Articles

Title Exploring the electronic and mechanical properties of protein using conducting atomic force microscopy
Author(s) Zhao, J
Davis, J
Sansom, M
Hung, A
Year 2004
Journal name Journal of the American Chemical Society
Volume number 126
Issue number 17
Start page 5601
End page 5601
Total pages 1
Publisher American Chemical Society
Abstract In interfacing man-made electronic components with specifically folded biomacromolecules, the perturbative effects of junction structure on any signal generated should be considered. We report herein on the electron-transfer characteristics of the blue copper metalloprotein, azurin, as characterized at a refined level by conducting atomic force microscopy (C-AFM). Specifically, the modulation of current-voltage (I-V) behavior with compressional force has been examined. In the absence of assignable resonant electron tunneling within the confined bias region, from -1 to 1 V, the I-V behavior was analyzed with a modified Simmons formula. To interpret the variation of tunneling barrier height and barrier length obtained by fitting with the modified Simmons formula, an atom packing density model associated with protein mechanical deformation was proposed and simulated by molecular dynamics. The barrier heights determined at the minimum forces necessary for stable electrical contact correlate reasonably well with those estimated from bulk biophysical (electroanalytical and photochemical) experiments previously reported. At higher forces, the tunnel barrier decreases to fall within the range observed with saturated organic systems. Molecular dynamics simulations revealed changes in secondary structure and atomic density of the protein with respect to compression. At low compression, where transport measurements are made, secondary structure is retained, and atomic packing density is observed to increase linearly with force. These predictions, and those made at higher compression, are consistent with both experimentally observed modulations of tunneling barrier height with applied force and the applicability of the atom packing density model of electron tunneling in proteins to molecular-level analyses.
Subject Macromolecular and Materials Chemistry not elsewhere classified
DOI - identifier 10.1021/ja039392a
ISSN 0002-7863
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