Direct Measurement of Electron Transfer Distance Decay Constants of Single Redox Proteins by Electrochemical Tunneling Spectroscopy

We present a method to measure directly and at the single-molecule level the distance decay constant that characterizes the rate of electron transfer (ET) in redox proteins. Using an electrochemical tunneling microscope under bipotentiostatic control, we obtained current−distance spectroscopic recor...

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Bibliographic Details
Published in:ACS nano 2011-03, Vol.5 (3), p.2060-2066
Main Authors: Artés, Juan M, Díez-Pérez, Ismael, Sanz, Fausto, Gorostiza, Pau
Format: Article
Language:English
Subjects:
Electron Transport
Microscopy, Scanning Tunneling - methods
Oxidation-Reduction
Proteins - chemistry
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Summary:We present a method to measure directly and at the single-molecule level the distance decay constant that characterizes the rate of electron transfer (ET) in redox proteins. Using an electrochemical tunneling microscope under bipotentiostatic control, we obtained current−distance spectroscopic recordings of individual redox proteins confined within a nanometric tunneling gap at a well-defined molecular orientation. The tunneling current decays exponentially, and the corresponding decay constant (β) strongly supports a two-step tunneling ET mechanism. Statistical analysis of decay constant measurements reveals differences between the reduced and oxidized states that may be relevant to the control of ET rates in enzymes and biological electron transport chains.
ISSN:1936-0851
1936-086X
DOI:10.1021/nn103236e