Electronic Decay Length in a Protein Molecule

Zhang, Bintian; Lindsay, Stuart

doi:10.1021/acs.nanolett.9b01254

Cited by 29 publications

(47 citation statements)

References 26 publications

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“…However, unlike DNA, proteins and peptides have heterogeneous charge distribution, making detection more challenging. Recently tunnelling detection of proteins has been experimentally shown using or STM-based recognition tunnelling platforms 18,38,39 . We confirmed the suitability of our probes for the detection of proteins, using a panel of three protein analytes with different molecular weight and charge, including streptavidin (SA), bovine serum albumin (BSA) and immunoglobin G (IgG) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

et al. 2021

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Quantum tunnelling offers a unique opportunity to study nanoscale objects with atomic resolution using electrical readout. However, practical implementation is impeded by the lack of simple, stable probes, that are required for successful operation. Existing platforms offer low throughput and operate in a limited range of analyte concentrations, as there is no active control to transport molecules to the sensor. We report on a standalone tunnelling probe based on double-barrelled capillary nanoelectrodes that do not require a conductive substrate to operate unlike other techniques, such as scanning tunnelling microscopy. These probes can be used to efficiently operate in solution environments and detect single molecules, including mononucleotides, oligonucleotides, and proteins. The probes are simple to fabricate, exhibit remarkable stability, and can be combined with dielectrophoretic trapping, enabling active analyte transport to the tunnelling sensor. The latter allows for up to 5-orders of magnitude increase in event detection rates and sub-femtomolar sensitivity.

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Section: Resultsmentioning

confidence: 99%

Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

et al. 2021

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“…1). Notably, we employ a four-electrode system with ionically blocking electrodes and measure steady-state electronic current (9,17) to avoid artifacts due to contact resistance (23,24), polarization resistance (25), and ionic currents (23), which are known to mask the intrinsic conductivity of the protein (23,26). Our studies show that amyloid proteins can efficiently transport charges over micrometer distances under ordinary thermal conditions without any need for redox-active metal cofactors.…”

Section: Significancementioning

confidence: 99%

“…In contrast, conductivity measurements involve the passage of charge through a protein without charge residing on the protein (30). Such conductivity measurements are extremely challenging due to contact resistances obscuring the intrinsic conductivity, as most of the applied voltage drop occurs across the contacts (23,26). Even single-molecule measurements have shown that protein conductance is strongly affected by the nature of contacts (23,26,27).…”

Section: Strategy To Measure Contact-free Electron Transport In Proteins Tomentioning

confidence: 99%

Intrinsic electronic conductivity of individual atomically resolved amyloid crystals reveals micrometer-long hole hopping via tyrosines

Shipps

Kelly

Dahl

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Proteins are commonly known to transfer electrons over distances limited to a few nanometers. However, many biological processes require electron transport over far longer distances. For example, soil and sediment bacteria transport electrons, over hundreds of micrometers to even centimeters, via putative filamentous proteins rich in aromatic residues. However, measurements of true protein conductivity have been hampered by artifacts due to large contact resistances between proteins and electrodes. Using individual amyloid protein crystals with atomic-resolution structures as a model system, we perform contact-free measurements of intrinsic electronic conductivity using a four-electrode approach. We find hole transport through micrometer-long stacked tyrosines at physiologically relevant potentials. Notably, the transport rate through tyrosines (105 s−1) is comparable to cytochromes. Our studies therefore show that amyloid proteins can efficiently transport charges, under ordinary thermal conditions, without any need for redox-active metal cofactors, large driving force, or photosensitizers to generate a high oxidation state for charge injection. By measuring conductivity as a function of molecular length, voltage, and temperature, while eliminating the dominant contribution of contact resistances, we show that a multistep hopping mechanism (composed of multiple tunneling steps), not single-step tunneling, explains the measured conductivity. Combined experimental and computational studies reveal that proton-coupled electron transfer confers conductivity; both the energetics of the proton acceptor, a neighboring glutamine, and its proximity to tyrosine influence the hole transport rate through a proton rocking mechanism. Surprisingly, conductivity increases 200-fold upon cooling due to higher availability of the proton acceptor by increased hydrogen bonding.

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“…It falls into the nanoSiemens scale, even over distances of several nanometers [4,5,6]. The conductance does not show significant decay by increasing the distance of the electrodes [7,8,9]. The conductance remains nearly constant when temperature is changed from tens of Kelvins to ambient temperatures [10].…”

Section: Introductionmentioning

confidence: 99%

“…The conductance does not show significant decay by increasing the distance of the electrodes [7,8,9].…”

Section: Introductionmentioning

confidence: 99%

A Landauer Formula for Bioelectronic Applications

et al. 2019

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Recent electronic transport experiments using metallic contacts attached to proteins identified some “stylized facts”, which contradict conventional wisdom that increasing either the spatial distance between the electrodes or the temperature suppresses conductance exponentially. These include nearly temperature-independent conductance over the protein in the 30 to 300 K range, distance-independent conductance within a single protein in the 1 to 10 nm range and an anomalously large conductance in the 0.1 to 10 nS range. In this paper, we develop a generalization of the low temperature Landauer formula, which can account for the joint effects of tunneling and decoherence and can explain these new experimental findings. We use novel approximations, which greatly simplify the mathematical treatment and allow us to calculate the conductance in terms of a handful macroscopic parameters, instead of the myriads of microscopic parameters describing the details of an atomic level quantum chemical computation. The new approach makes it possible to get predictions for the outcomes of new experiments without relying solely on high performance computing and can distinguish important and unimportant details of the protein structures from the point of view of transport properties.

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Electronic Decay Length in a Protein Molecule

Cited by 29 publications

References 26 publications

Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

Intrinsic electronic conductivity of individual atomically resolved amyloid crystals reveals micrometer-long hole hopping via tyrosines

A Landauer Formula for Bioelectronic Applications

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