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Electron Tunneling through Pseudomonas aeruginosa Azurins on SAM Gold Electrodes

Yokoyama, Keiko and Leigh, Brian S. and Sheng, Yuling and Niki, Katsumi and Nakamura, Nobuhumi and Ohno, Hiroyuki and Winkler, Jay R. and Gray, Harry B. and Richards, John H. (2008) Electron Tunneling through Pseudomonas aeruginosa Azurins on SAM Gold Electrodes. Inorganica Chimica Acta, 361 (4). pp. 1095-1099. ISSN 0020-1693. PMCID PMC2390814. doi:10.1016/j.ica.2007.08.022.

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Robust voltammetric responses were obtained for wild-type and Y72F/H83Q/Q107H/Y108F azurins adsorbed on CH_3(CH_2)_nSH:HO(CH_2)_mSH (n=m=4,6,8,11; n=13,15 m=11) self-assembled monolayer (SAM) gold electrodes in acidic solution (pH 4.6) at high ionic strengths. Electron-transfer (ET) rates do not vary substantially with ionic strength, suggesting that the SAM methyl headgroup binds to azurin by hydrophobic interactions. The voltammetric responses for both proteins at higher pH values (>4.6 to 11) also were strong. A binding model in which the SAM hydroxyl headgroup interacts with the Asn47 carboxamide accounts for the relatively strong coupling to the copper center that can be inferred from the ET rates. Of particular interest is the finding that rate constants for electron tunneling through n = 8, 13 SAMs are higher at pH 11 than those at pH 4.6, possibly owing to enhanced coupling of the SAM to Asn 47 caused by deprotonation of nearby surface residues.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Winkler, Jay R.0000-0002-4453-9716
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 2007 Elsevier. Received 1 August 2007; accepted 18 August 2007; Available online 30 August 2007. Dedicated to Edward Solomon in appreciation of his pioneering work on blue copper proteins. This work was supported by NIH DK19038.
Funding AgencyGrant Number
Subject Keywords:Azurin; Electron transfer; SAM; Ionic strength; pH
Issue or Number:4
PubMed Central ID:PMC2390814
Record Number:CaltechAUTHORS:20150424-150000195
Persistent URL:
Official Citation:Keiko Yokoyama, Brian S. Leigh, Yuling Sheng, Katsumi Niki, Nobuhumi Nakamura, Hiroyuki Ohno, Jay R. Winkler, Harry B. Gray, John H. Richards, Electron tunneling through Pseudomonas aeruginosa azurins on SAM gold electrodes, Inorganica Chimica Acta, Volume 361, Issue 4, 3 March 2008, Pages 1095-1099, ISSN 0020-1693, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56973
Deposited By: George Porter
Deposited On:24 Apr 2015 22:29
Last Modified:10 Nov 2021 21:06

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