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Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction

[Image: see text] We observe reversible, bias-induced switching of conductance via a blue copper protein azurin mutant, N42C Az, with a nearly 10-fold increase at |V| > 0.8 V than at lower bias. No such switching is found for wild-type azurin, WT Az, up to |1.2 V|, beyond which irreversible chang...

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Autores principales: Fereiro, Jerry A., Bendikov, Tatyana, Pecht, Israel, Sheves, Mordechai, Cahen, David
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2020
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662909/
https://www.ncbi.nlm.nih.gov/pubmed/33141577
http://dx.doi.org/10.1021/jacs.0c08836
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author Fereiro, Jerry A.
Bendikov, Tatyana
Pecht, Israel
Sheves, Mordechai
Cahen, David
author_facet Fereiro, Jerry A.
Bendikov, Tatyana
Pecht, Israel
Sheves, Mordechai
Cahen, David
author_sort Fereiro, Jerry A.
collection PubMed
description [Image: see text] We observe reversible, bias-induced switching of conductance via a blue copper protein azurin mutant, N42C Az, with a nearly 10-fold increase at |V| > 0.8 V than at lower bias. No such switching is found for wild-type azurin, WT Az, up to |1.2 V|, beyond which irreversible changes occur. The N42C Az mutant will, when positioned between electrodes in a solid-state Au–protein–Au junction, have an orientation opposite that of WT Az with respect to the electrodes. Current(s) via both proteins are temperature-independent, consistent with quantum mechanical tunneling as dominant transport mechanism. No noticeable difference is resolved between the two proteins in conductance and inelastic electron tunneling spectra at <|0.5 V| bias voltages. Switching behavior persists from 15 K up to room temperature. The conductance peak is consistent with the system switching in and out of resonance with the changing bias. With further input from UV photoemission measurements on Au–protein systems, these striking differences in conductance are rationalized by having the location of the Cu(II) coordination sphere in the N42C Az mutant, proximal to the (larger) substrate-electrode, to which the protein is chemically bound, while for the WT Az that coordination sphere is closest to the other Au electrode, with which only physical contact is made. Our results establish the key roles that a protein’s orientation and binding nature to the electrodes play in determining the electron transport tunnel barrier.
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spelling pubmed-76629092020-11-13 Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction Fereiro, Jerry A. Bendikov, Tatyana Pecht, Israel Sheves, Mordechai Cahen, David J Am Chem Soc [Image: see text] We observe reversible, bias-induced switching of conductance via a blue copper protein azurin mutant, N42C Az, with a nearly 10-fold increase at |V| > 0.8 V than at lower bias. No such switching is found for wild-type azurin, WT Az, up to |1.2 V|, beyond which irreversible changes occur. The N42C Az mutant will, when positioned between electrodes in a solid-state Au–protein–Au junction, have an orientation opposite that of WT Az with respect to the electrodes. Current(s) via both proteins are temperature-independent, consistent with quantum mechanical tunneling as dominant transport mechanism. No noticeable difference is resolved between the two proteins in conductance and inelastic electron tunneling spectra at <|0.5 V| bias voltages. Switching behavior persists from 15 K up to room temperature. The conductance peak is consistent with the system switching in and out of resonance with the changing bias. With further input from UV photoemission measurements on Au–protein systems, these striking differences in conductance are rationalized by having the location of the Cu(II) coordination sphere in the N42C Az mutant, proximal to the (larger) substrate-electrode, to which the protein is chemically bound, while for the WT Az that coordination sphere is closest to the other Au electrode, with which only physical contact is made. Our results establish the key roles that a protein’s orientation and binding nature to the electrodes play in determining the electron transport tunnel barrier. American Chemical Society 2020-11-03 2020-11-11 /pmc/articles/PMC7662909/ /pubmed/33141577 http://dx.doi.org/10.1021/jacs.0c08836 Text en © 2020 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Fereiro, Jerry A.
Bendikov, Tatyana
Pecht, Israel
Sheves, Mordechai
Cahen, David
Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title_full Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title_fullStr Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title_full_unstemmed Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title_short Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction
title_sort protein binding and orientation matter: bias-induced conductance switching in a mutated azurin junction
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662909/
https://www.ncbi.nlm.nih.gov/pubmed/33141577
http://dx.doi.org/10.1021/jacs.0c08836
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