1
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Fereiro JA, Bendikov T, Pecht I, Sheves M, Cahen D. Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction. J Am Chem Soc 2020; 142:19217-19225. [PMID: 33141577 PMCID: PMC7662909 DOI: 10.1021/jacs.0c08836] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 02/07/2023]
Abstract
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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Affiliation(s)
- Jerry A. Fereiro
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Tatyana Bendikov
- Department
of Chemical Research Support, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Israel Pecht
- Department
of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Mordechai Sheves
- Department
of Organic Chemistry, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - David Cahen
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
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2
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Bizzarri AR, Baldacchini C, Cannistraro S. Structure, Dynamics, and Electron Transfer of Azurin Bound to a Gold Electrode. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:9190-9200. [PMID: 28789529 DOI: 10.1021/acs.langmuir.7b01102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Blue copper redox protein azurin (AZ) constitutes an ideal active element for building bionano-optoelectronic devices based on the intriguing interplay among its electron transfer (ET), vibrational, and optical properties. A full comprehension of its dynamical and functional behavior is required for efficient applications. Here, AZ bound to gold electrode via its disulfide bridge was investigated by a molecular dynamics simulation approach taking into account for gold electron polarization which provides a more realistic description of the protein-gold interaction. Upon binding to gold, AZ undergoes slight changes in its secondary structure with the preservation of the copper-containing active site structure. Binding of AZ to gold promotes new collective motions, with respect to free AZ, as evidenced by essential dynamics. Analysis of the ET from the AZ copper ion to the gold substrate, performed by the Pathways model, put into evidence the main residues and structural motifs of AZ involved in the ET paths. During the dynamical evolution of the bionanosystem, transient contacts between some lateral protein atoms and the gold substrate occurred; concomitantly, the opening of additional ET channels with much higher rates was registered. These results provide new and detailed insights on the dynamics and ET properties of the AZ-gold system, by also helping to rationalize some imaging and conductive experimental evidences and also to design new bionanodevices with tailored features.
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Affiliation(s)
- Anna Rita Bizzarri
- Biophysics & Nanoscience Centre, DEB, Università della Tuscia , Viterbo 01100, Italy
| | - Chiara Baldacchini
- Biophysics & Nanoscience Centre, DEB, Università della Tuscia , Viterbo 01100, Italy
- IBAF-CNR , Porano 05010, Italy
| | - Salvatore Cannistraro
- Biophysics & Nanoscience Centre, DEB, Università della Tuscia , Viterbo 01100, Italy
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3
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Stan RC, Kros A, Akkilic N, Sanghamitra NJ, Appel J. Direct wiring of the azurin redox center to gold electrodes investigated by protein film voltammetry. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2017.01.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Abstract
Understanding protein-inorganic surface interactions is central to the rational design of new tools in biomaterial sciences, nanobiotechnology and nanomedicine. Although a significant amount of experimental research on protein adsorption onto solid substrates has been reported, many aspects of the recognition and interaction mechanisms of biomolecules and inorganic surfaces are still unclear. Theoretical modeling and simulations provide complementary approaches for experimental studies, and they have been applied for exploring protein-surface binding mechanisms, the determinants of binding specificity towards different surfaces, as well as the thermodynamics and kinetics of adsorption. Although the general computational approaches employed to study the dynamics of proteins and materials are similar, the models and force-fields (FFs) used for describing the physical properties and interactions of material surfaces and biological molecules differ. In particular, FF and water models designed for use in biomolecular simulations are often not directly transferable to surface simulations and vice versa. The adsorption events span a wide range of time- and length-scales that vary from nanoseconds to days, and from nanometers to micrometers, respectively, rendering the use of multi-scale approaches unavoidable. Further, changes in the atomic structure of material surfaces that can lead to surface reconstruction, and in the structure of proteins that can result in complete denaturation of the adsorbed molecules, can create many intermediate structural and energetic states that complicate sampling. In this review, we address the challenges posed to theoretical and computational methods in achieving accurate descriptions of the physical, chemical and mechanical properties of protein-surface systems. In this context, we discuss the applicability of different modeling and simulation techniques ranging from quantum mechanics through all-atom molecular mechanics to coarse-grained approaches. We examine uses of different sampling methods, as well as free energy calculations. Furthermore, we review computational studies of protein-surface interactions and discuss the successes and limitations of current approaches.
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5
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Wu H, Feng X, Kieviet BD, Zhang K, Zandvliet HJ, Canters GW, Schön PM, Vancso GJ. Electrochemical atomic force microscopy reveals potential stimulated height changes of redox responsive Cu-azurin on gold. Eur Polym J 2016. [DOI: 10.1016/j.eurpolymj.2015.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Baldacchini C, Bizzarri AR, Cannistraro S. Electron transfer, conduction and biorecognition properties of the redox metalloprotein Azurin assembled onto inorganic substrates. Eur Polym J 2016. [DOI: 10.1016/j.eurpolymj.2016.04.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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7
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Plegaria JS, Duca M, Tard C, Friedlander TJ, Deb A, Penner-Hahn JE, Pecoraro VL. De novo design and characterization of copper metallopeptides inspired by native cupredoxins. Inorg Chem 2015; 54:9470-82. [PMID: 26381361 DOI: 10.1021/acs.inorgchem.5b01330] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using de novo protein design, we incorporated a copper metal binding site within the three-helix bundle α3D (Walsh et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5486-5491) to assess whether a cupredoxin center within an α-helical domain could mimic the spectroscopic, structural, and redox features of native type-1 copper (CuT1) proteins. We aimed to determine whether a CuT1 center could be realized in a markedly different scaffold rather than the native β-barrel fold and whether the characteristic short Cu-S bond (2.1-2.2 Å) and positive reduction potentials could be decoupled from the spectroscopic properties (ε600 nm = 5000 M(-1) cm(-1)) of such centers. We incorporated 2HisCys(Met) residues in three distinct α3D designs designated core (CR), chelate (CH), and chelate-core (ChC). XAS analysis revealed a coordination environment similar to reduced CuT1 proteins, producing Cu-S(Cys) bonds ranging from 2.16 to 2.23 Å and Cu-N(His) bond distances of 1.92-1.99 Å. However, Cu(II) binding to the CR and CH constructs resulted in tetragonal type-2 copper-like species, displaying an intense absorption band between 380 and 400 nm (>1500 M(-1) cm(-1)) and A|| values of (150-185) × 10(-4) cm(-4). The ChC construct, which possesses a metal-binding site deeper in its helical bundle, yielded a CuT1-like brown copper species, with two absorption bands at 401 (4429 M(-1) cm(-1)) and 499 (2020 M(-1) cm(-1)) nm and an A|| value ∼30 × 10(-4) cm(-4) greater than its native counterparts. Electrochemical studies demonstrated reduction potentials of +360 to +460 mV (vs NHE), which are within the observed range for azurin and plastocyanin. These observations showed that the designed metal binding sites lacked the necessary rigidity to enforce the appropriate structural constraints for a Cu(II) chromophore (EPR and UV-vis); however, the Cu(I) structural environment and the high positive potential of CuT1 centers were recapitulated within the α-helical bundle of α3D.
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Affiliation(s)
| | - Matteo Duca
- Laboratoire d'Electrochimie Moléculaire, UMR 7591, CNRS, Université Paris Diderot, Sorbonne Paris Cité , 15 Rue Jean Antoine de Baïf, F-75205 Paris Cedex 13, France
| | - Cédric Tard
- Laboratoire d'Electrochimie Moléculaire, UMR 7591, CNRS, Université Paris Diderot, Sorbonne Paris Cité , 15 Rue Jean Antoine de Baïf, F-75205 Paris Cedex 13, France
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8
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Giannotti MI, Cabeza de Vaca I, Artés JM, Sanz F, Guallar V, Gorostiza P. Direct Measurement of the Nanomechanical Stability of a Redox Protein Active Site and Its Dependence upon Metal Binding. J Phys Chem B 2015; 119:12050-8. [DOI: 10.1021/acs.jpcb.5b06382] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marina I. Giannotti
- Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28029, Spain
- Physical
Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain
- Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, Barcelona 08028, Spain
| | - Israel Cabeza de Vaca
- Joint
BSC-CRG-IRB Research Program in Computational Biology, Barcelona Supercomputing Center, Jordi Girona 29, Barcelona 08034, Spain
| | - Juan M. Artés
- Physical
Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain
- Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, Barcelona 08028, Spain
| | - Fausto Sanz
- Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28029, Spain
- Physical
Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain
- Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, Barcelona 08028, Spain
| | - Victor Guallar
- Joint
BSC-CRG-IRB Research Program in Computational Biology, Barcelona Supercomputing Center, Jordi Girona 29, Barcelona 08034, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
| | - Pau Gorostiza
- Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28029, Spain
- Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, Barcelona 08028, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
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9
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Amdursky N, Sepunaru L, Raichlin S, Pecht I, Sheves M, Cahen D. Electron Transfer Proteins as Electronic Conductors: Significance of the Metal and Its Binding Site in the Blue Cu Protein, Azurin. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2015; 2:1400026. [PMID: 27980928 PMCID: PMC5115354 DOI: 10.1002/advs.201400026] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/08/2015] [Indexed: 05/07/2023]
Abstract
Electron transfer (ET) proteins are biomolecules with specific functions, selected by evolution. As such they are attractive candidates for use in potential bioelectronic devices. The blue copper protein azurin (Az) is one of the most-studied ET proteins. Traditional spectroscopic, electrochemical, and kinetic methods employed for studying ET to/from the protein's Cu ion have been complemented more recently by studies of electrical conduction through a monolayer of Az in the solid-state, sandwiched between electrodes. As the latter type of measurement does not require involvement of a redox process, it also allows monitoring electronic transport (ETp) via redox-inactive Az-derivatives. Here, results of macroscopic ETp via redox-active and -inactive Az derivatives, i.e., Cu(II) and Cu(I)-Az, apo-Az, Co(II)-Az, Ni(II)-Az, and Zn(II)-Az are reported and compared. It is found that earlier reported temperature independence of ETp via Cu(II)-Az (from 20 K until denaturation) is unique, as ETp via all other derivatives is thermally activated at temperatures >≈200 K. Conduction via Cu(I)-Az shows unexpected temperature dependence >≈200 K, with currents decreasing at positive and increasing at negative bias. Taking all the data together we find a clear compensation effect of Az conduction around the Az denaturation temperature. This compensation can be understood by viewing the Az binding site as an electron trap, unless occupied by Cu(II), as in the native protein, with conduction of the native protein setting the upper transport efficiency limit.
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Affiliation(s)
- Nadav Amdursky
- Departments of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel; Departments of Organic Chemistry Weizmann Institute of Science Rehovot 76100 Israel
| | - Lior Sepunaru
- Departments of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel
| | - Sara Raichlin
- Departments of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel; Departments of Organic Chemistry Weizmann Institute of Science Rehovot 76100 Israel
| | - Israel Pecht
- Departments of Immunology Weizmann Institute of Science Rehovot 76100 Israel
| | - Mordechai Sheves
- Departments of Organic Chemistry Weizmann Institute of Science Rehovot 76100 Israel
| | - David Cahen
- Departments of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel
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10
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Nakajima H, Miyazaki S, Itoh T, Hayamura M, Watanabe Y. Azurin–DNA Conjugate with the Binding Motif of a Transcriptional Regulator, CooA: CO-dependent Modulation of the Electron-transfer Reaction. CHEM LETT 2014. [DOI: 10.1246/cl.140284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - Soji Miyazaki
- Research Centre of Materials Science, Nagoya University
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11
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Amdursky N, Pecht I, Sheves M, Cahen D. Electron Transport via Cytochrome C on Si–H Surfaces: Roles of Fe and Heme. J Am Chem Soc 2013; 135:6300-6. [DOI: 10.1021/ja4015474] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Nadav Amdursky
- Departments
of Materials and Interfaces, ‡Organic Chemistry, and §Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Israel Pecht
- Departments
of Materials and Interfaces, ‡Organic Chemistry, and §Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Mordechai Sheves
- Departments
of Materials and Interfaces, ‡Organic Chemistry, and §Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David Cahen
- Departments
of Materials and Interfaces, ‡Organic Chemistry, and §Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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Li W, Sepunaru L, Amdursky N, Cohen SR, Pecht I, Sheves M, Cahen D. Temperature and force dependence of nanoscale electron transport via the Cu protein azurin. ACS NANO 2012; 6:10816-10824. [PMID: 23136937 DOI: 10.1021/nn3041705] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Solid-state electron transport (ETp) via a monolayer of immobilized azurin (Az) was examined by conducting probe atomic force microscopy (CP-AFM), as a function of both temperature (248-373K) and applied tip force (6-15 nN). At low forces, ETp via holo-Az (with Cu(2+)) is temperature-independent, but thermally activated via the Cu-depleted form of Az, apo-Az. While this observation agrees with those of macroscopic-scale measurements, we find that for holo-Az the mechanism of ETp at high temperatures changes upon an increase in the force applied by the tip to the proteins; namely, above 310 K and forces >6 nN ETp becomes thermally activated. This is in contrast to apo-Az, where increasing applied force causes only small monotonic increases in currents due to decreased electrode separation. The distinct ETp temperature dependence of holo- and apo-Az is assigned to a difference in structural response to pressure between the two protein forms. An important implication of these CP-AFM results (of measurements over a significant temperature range) is that for reliable ETp measurements on flexible macromolecules, such as proteins, the pressure applied during the measurements should be controlled or at least monitored.
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Affiliation(s)
- Wenjie Li
- Department of Materials & Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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13
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Elmalk AT, Salverda JM, Tabares LC, Canters GW, Aartsma TJ. Probing redox proteins on a gold surface by single molecule fluorescence spectroscopy. J Chem Phys 2012; 136:235101. [PMID: 22779620 DOI: 10.1063/1.4728107] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The interaction between the fluorescently labeled redox protein, azurin, and a thin gold film is characterized using single-molecule fluorescence intensity and lifetime measurements. Fluorescence quenching starts at distances below 2.3 nm from the gold surface. At shorter distances the quantum yield may decrease down to fourfold for direct attachment of the protein to bare gold. Outside of the quenching range, up to fivefold enhancement of the fluorescence is observed on average with increasing roughness of the gold layer. Fluorescence-detected redox activity of individual azurin molecules, with a lifetime switching ratio of 0.4, is demonstrated for the first time close to a gold surface.
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Affiliation(s)
- Abdalmohsen T Elmalk
- Leiden Institute of Physics, Leiden University, Huygens Laboratory, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
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14
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Voltammetric study of the adsorbed thermophilic plastocyanin from Phormidium laminosum up to 90°C. Electrochem commun 2012. [DOI: 10.1016/j.elecom.2012.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Ashur I, Schulz O, McIntosh CL, Pinkas I, Ros R, Jones AK. Transparent gold as a platform for adsorbed protein spectroelectrochemistry: investigation of cytochrome c and azurin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5861-5871. [PMID: 22369317 DOI: 10.1021/la300404r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The majority of protein spectroelectrochemical methods utilize a diffusing, chemical mediator to exchange electrons between the electrode and the protein. In such methods, electrochemical potential control is limited by mediator choice and its ability to interact with the protein of interest. We report an approach for unmediated, protein spectroelectrochemistry that overcomes this limitation by adsorbing protein directly to thiol self-assembled monolayer (SAM) modified, thin (10 nm), semitransparent gold. The viability of the method is demonstrated with two diverse and important redox proteins: cytochrome c and azurin. Fast, reversible electrochemical signals comparable to those previously reported for these proteins on ordinary disk gold electrodes were observed. Although the quantity of protein in a submonolayer adsorbed at an electrode is expected to be insufficient for detection of UV-vis absorption bands based on bulk extinction coefficients, excellent spectra were detected for each of the proteins in the adsorbed state. Furthermore, AFM imaging confirmed that only a single layer of protein was adsorbed to the electrode. We hypothesize that interaction of the relatively broad gold surface plasmon with the proteins' electronic transitions results in surface signal enhancement of the molecular transitions of between 8 and 112 times, allowing detection of the proteins at much lower than expected concentrations. Since many other proteins are known to interact with gold SAMs and the technical requirements for implementation of these experiments are simple, this approach is expected to be very generally applicable to exploring mechanisms of redox proteins and enzymes as well as development of sensors and other redox protein based applications.
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Affiliation(s)
- Idan Ashur
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States
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16
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Patil AV, Premaraban T, Berthoumieu O, Watts A, Davis JJ. Engineered Bacteriorhodopsin: A Molecular Scale Potential Switch. Chemistry 2012; 18:5632-6. [DOI: 10.1002/chem.201103597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/24/2012] [Indexed: 11/10/2022]
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17
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Direct Electrochemistry and Electrocatalysis of Myoglobin with Ionic Liquid through Multilayers Film on Carbon Ionic Liquid Electrode. J CHIN CHEM SOC-TAIP 2011. [DOI: 10.1002/jccs.201190147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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Sun A, Zheng J, Sheng Q. A Novel Hydrogen Peroxide Biosensor Based on the PDDA-GNPs/MWNTs Nanocomposite Matrix. J CHIN CHEM SOC-TAIP 2011. [DOI: 10.1002/jccs.201190136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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19
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20
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Majidi MR, Saadatirad A, Alipour E. Voltammetric Determination of Hemoglobin Using a Pencil Lead Electrode. ELECTROANAL 2011. [DOI: 10.1002/elan.201100009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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21
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Choi M, Davidson VL. Cupredoxins--a study of how proteins may evolve to use metals for bioenergetic processes. Metallomics 2011; 3:140-51. [PMID: 21258692 DOI: 10.1039/c0mt00061b] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cupredoxins are small proteins that contain type I copper centers, which are ubiquitous in nature. They function as electron transfer shuttles between proteins. This review of the structure and properties of native cupredoxins, and those modified by site-directed mutagenesis, illustrates how these proteins may have evolved to specifically bind copper, develop recognition sites for specific redox partners, tune redox potential for a particular function, and allow for efficient electron transfer through the protein matrix. This is relevant to the general understanding of the roles of metals in energy metabolism, respiration and photosynthesis.
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Affiliation(s)
- Moonsung Choi
- Department of Biochemistry, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216-4505, USA
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22
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Patil AV, Davis JJ. Visualizing and Tuning Thermodynamic Dispersion in Metalloprotein Monolayers. J Am Chem Soc 2010; 132:16938-44. [DOI: 10.1021/ja1065448] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Amol Virendra Patil
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Jason John Davis
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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23
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A whisker-like carbon composite for the immobilization of laccase and its bioelectrochemistry. Sci China Chem 2010. [DOI: 10.1007/s11426-010-3186-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Vargo ML, Gulka CP, Gerig JK, Manieri CM, Dattelbaum JD, Marks CB, Lawrence NT, Trawick ML, Leopold MC. Distance dependence of electron transfer kinetics for azurin protein adsorbed to monolayer protected nanoparticle film assemblies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:560-569. [PMID: 19678633 DOI: 10.1021/la9020367] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The distance dependence and kinetics of the heterogeneous electron transfer (ET) reaction for the redox protein azurin adsorbed to an electrode modified with a gold nanoparticle film are investigated using cyclic voltammetry. The nanoparticle films are comprised of nonaqueous nanoparticles, known as monolayer-protected clusters (MPCs), which are covalently networked with dithiol linkers. The MPC film assembly serves as an alternative adsorption platform to the traditional alkanethiolate self-assembled monolayer (SAM) modified electrodes that are commonly employed to study the ET kinetics of immobilized redox proteins, a strategy known as protein monolayer electrochemistry. Voltammetric analysis of the ET kinetics for azurin adsorbed to SAMs of increasing chain length results in quasi-reversible voltammetry with significant peak splitting. We observed rate constants (k degrees (ET)) of 12-20 s(-1) for the protein at SAMs of shorter alkanethiolates that decays exponentially (beta = 0.9/CH(2) or 0.8/A) at SAMs of longer alkanethiolates (9-11 methylene units) or an estimated distance of 1.23 nm and is representative of classical electronic tunneling behavior over increasing distance. Azurin adsorbed to the MPC film platforms of increasing thickness results in reversible voltammetry with very little voltammetric peaks splitting and nearly negligible decay of the ET rate over significant distances up to 20 nm. The apparent lack of distance dependence for heterogeneous ET reactions at MPC film assemblies is attributed to a two-step mechanism involving extremely fast electronic hopping through the MPC film architecture. These results suggest that MPC platforms may be used in protein monolayer electrochemistry to create adsorption platforms of higher architecture that can accommodate greater than monolayer protein coverage and increase the Faradaic signal, a finding with significant implications for amperometric biosensor design and development.
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Affiliation(s)
- Morgan L Vargo
- Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23173, USA
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Ranieri A, Battistuzzi G, Borsari M, Casalini S, Fontanesi C, Monari S, Siwek MJ, Sola M. Thermodynamics and kinetics of the electron transfer process of spinach plastocyanin adsorbed on a modified gold electrode. J Electroanal Chem (Lausanne) 2009. [DOI: 10.1016/j.jelechem.2008.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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26
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Szymańska I, Orlewska C, Janssen D, Dehaen W, Radecka H. Dipyrromethene–dodecanethiol self-assembled monolayers deposited onto gold electrodes. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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27
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Szymańska I, Stobiecka M, Orlewska C, Rohand T, Janssen D, Dehaen W, Radecka H. Electroactive dipyrromethene-Cu(II) self-assembled monolayers: complexation reaction on the surface of gold electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11239-11245. [PMID: 18781792 DOI: 10.1021/la801164f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In the work presented, thiol- and COOH-terminated dipyrromethene derivatives have been applied for gold electrode modification. Dipyrromethene deposited onto a solid support, after binding Cu2+, can act as a redox active monolayer. The complexation of Cu(II) ions has been performed on the surface of gold electrodes modified with dipyrromethene. The characterization of dipyrromethene-Cu(II) self-assembled monolayers (SAMs) has been done by cyclic voltammetry (CV), wettability contact angle measurements, and atomic force microscopy (AFM). The new electroactive monolayer could be applied for the immobilization of proteins and ssDNA or for electrochemical anion sensing without redox markers in the solution.
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Affiliation(s)
- Iwona Szymańska
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn, Poland
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Zhang J, Kuznetsov AM, Medvedev IG, Chi Q, Albrecht T, Jensen PS, Ulstrup J. Single-Molecule Electron Transfer in Electrochemical Environments. Chem Rev 2008; 108:2737-91. [PMID: 18620372 DOI: 10.1021/cr068073+] [Citation(s) in RCA: 252] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Léger C, Bertrand P. Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies. Chem Rev 2008; 108:2379-438. [DOI: 10.1021/cr0680742] [Citation(s) in RCA: 594] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Liu C, Hu J. Direct Electrochemistry of Hemoglobin Entrapped in Composite Electrodeposited Chitosan-Multiwall Carbon Nanotubes and Nanogold Particles Membrane and Its Electrocatalytic Application. ELECTROANAL 2008. [DOI: 10.1002/elan.200704150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Ma GX, Wang YG, Wang CX, Lu TH, Xia YY. Hemoglobin immobilized on whisker-like carbon composites and its direct electrochemistry. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.01.092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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32
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Protein electrodes with direct electrochemical communication. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2008; 109:19-64. [PMID: 17928972 DOI: 10.1007/10_2007_083] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Electrochemistry using direct electron transfer between an electrode and a protein or an enzyme has developed into a means for studying biological redox reactions and for bioanalytics, biosynthesis and bioenergetics. This review summarizes recent work on direct protein electrochemistry with special emphasis on our results in bioelectrocatalysis using isolated enzymes and enzyme-protein couples.
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Ludden MJW, Sinha JK, Wittstock G, Reinhoudt DN, Huskens J. Control over binding stoichiometry and specificity in the supramolecular immobilization of cytochrome c on a molecular printboard. Org Biomol Chem 2008; 6:1553-7. [DOI: 10.1039/b718940k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Ma GX, Lu TH, Xia YY. Direct electrochemistry and bioelectrocatalysis of hemoglobin immobilized on carbon black. Bioelectrochemistry 2007; 71:180-5. [PMID: 17499558 DOI: 10.1016/j.bioelechem.2007.04.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 03/01/2007] [Accepted: 04/07/2007] [Indexed: 11/30/2022]
Abstract
It is reported for the first time that hemoglobin (Hb) was immobilized on the surface of carbon black powders modified at the surface of a glassy carbon electrode. The cyclic voltammetric results showed that the immobilized Hb could undergo a direct quasi-reversible electrochemical reaction. Its formal potential, E(0), is -0.330 V in phosphate buffer solution (pH 6.9) at a scan rate of 100 mV/s and is almost independent of the scan rate in the range of 40-200 mV/s. The dependence of E(0), on the pH of the buffer solution indicated that the conversion of Hb-Fe(III)/Hb-Fe(II) is a one-electron-transfer reaction process coupled with one-proton-transfer. The experimental results also demonstrated that the immobilized Hb retained its bioelectrocatalytic activity for the reduction of H(2)O(2). Furthermore, the immobilized Hb can be stored at 4 degrees C for several weeks without any loss of the enzyme activity. Thus, the immobilized Hb may be used as a biocathodic catalyst in biofuel cells.
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Affiliation(s)
- Guo-Xian Ma
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, PR China
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35
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Wigginton NS, Rosso KM, Hochella MF. Mechanisms of Electron Transfer in Two Decaheme Cytochromes from a Metal-Reducing Bacterium. J Phys Chem B 2007; 111:12857-64. [DOI: 10.1021/jp0718698] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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36
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Andolfi L, Caroppi P, Bizzarri AR, Piro MC, Sinibaldi F, Ferri T, Polticelli F, Cannistraro S, Santucci R. Nanoscopic and redox characterization of engineered horse cytochrome C chemisorbed on a bare gold electrode. Protein J 2007; 26:271-9. [PMID: 17200882 DOI: 10.1007/s10930-006-9069-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In this paper, we exploit the potential offered by site-directed mutagenesis to achieve direct adsorption of horse cyt c on a bare gold electrode surface. To this issue, the side chain T102 has been replaced by a cysteine. T102 is close to the surface exposed C-terminal residue (E104), therefore the T102C mutation is expected to generate an exposed cysteine side chain able to facilitate protein binding to the electrode via the sulphur atom (analogously to what observed for yeast iso-1-cyt c). Scanning Tunnelling and Tapping Mode Atomic Force Microscopy measurements show that the T102C mutant stably adsorbs on an Au(111) surface and retains the morphological characteristics of the native form. Cyclic voltammetry reveals that the adsorbed variant is electroactive; however, the heterogeneous electron transfer with the electrode surface is slower than that observed for yeast iso-1-cyt c. We ascribe it to differences in the tertiary architecture of the two proteins, characterized by different flexibility and stability. In particular, the region where the N- and C-terminal helices get in contact (and where the mutation occurs) is analyzed in detail, since the interactions between these two helices are considered crucial for the stability of the overall protein fold.
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Affiliation(s)
- Laura Andolfi
- Biophysics and Nanoscience Centre, CNISM, Dipartimento di Scienze Ambientali, Università della Tuscia, 01100 Viterbo, Italy
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37
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Axford D, Davis JJ, Wang N, Wang D, Zhang T, Zhao J, Peters B. Molecularly Resolved Protein Electromechanical Properties. J Phys Chem B 2007; 111:9062-8. [PMID: 17628094 DOI: 10.1021/jp070262o] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previous work has shown that protein molecules can be trapped between the conductive surfaces presented by a metal-coated AFM probe and an underlying planar substrate where their molecule-specific conductance characteristics can be assayed. Herein, we demonstrate that transport across such a derived metal-protein-electrode junction falls within three, pressure-dependent, regimes and, further, that pressure-dependent conductance can be utilized in analyzing temporal variations of protein fold. Specifically, the electronic and mechanical properties of the metalloprotein azurin have been characterized under conditions of anisotropic vertical compression through the use of a conducting atomic force microscope (CP-AFM). By utilizing the ability of azurin to chemically self-assemble on the gold surface presented either by the apex of a suitably coated AFM probe or a planar metallic surface, molecular-level transport characteristics are assayable. Under conditions of low force, typically less than 2 nN, the weak physical and electronic coupling between the protein and the conducting contacts impedes tunneling and leads to charge buildup followed by dielectric breakdown. At slightly increased force, 3-5 nN, the copper protein exhibits temporal electron occupation with observable negative differential resistance, while the redox-inactive zinc mutant does not. At imposed loads greater than 5 nN, appreciable electron tunneling can be detected even at low bias for both the redox-active and -inactive species. Dynamic current-voltage characteristics have been recorded and are well-described by a modified Simmons tunneling model. Subsequent analyses enable the electron tunneling barrier height and barrier length to be determined under conditions of quantified vertical stress. The variance observed describes, in essence, the protein's mechanical properties within the confines of the tunnel junction.
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Affiliation(s)
- Daniel Axford
- Chemical Research Laboratory, Mansfield Road, University of Oxford, Oxford OX1 3TA, United Kingdom
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Astier Y, Canters GW, Davis JJ, Hill HAO, Verbeet MP, Wijma HJ. Sensing nitrite through a pseudoazurin-nitrite reductase electron transfer relay. Chemphyschem 2006; 6:1114-20. [PMID: 15900523 DOI: 10.1002/cphc.200400384] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Nitrite is converted to nitric oxide by haem or copper-containing enzymes in denitrifying bacteria during the process of denitrification. In designing an efficient biosensor, this enzymic turnover must be quantitatively assessed. The enzyme nitrite reductase from Alcaligenes faecalis contains a redox-active blue copper centre and a nonblue enzyme-active copper centre. It can be covalently tethered to modified gold-electrode surfaces in configurations in which direct electron transfer is possible. A surface cysteine mutant of the enzyme can be similarly immobilised on bare electroactive gold substrates. Under such circumstances, however, electron transfer cannot be effectively coupled with substrate catalytic turnover. In using either the natural redox partner, pseudoazurin, or ruthenium hexammine as an "electron-shuttle" or "conduit" between enzyme and a peptide-modified electrode surface, the coupling of electron transfer to catalysis can be utilised in the development of an amperometric nitrite sensor.
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Affiliation(s)
- Yann Astier
- Inorganic Chemistry Laboratory, University of Oxford, UK
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39
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Davis JJ, Burgess H, Zauner G, Kuznetsova S, Salverda J, Aartsma T, Canters GW. Monitoring Interfacial Bioelectrochemistry Using a FRET Switch. J Phys Chem B 2006; 110:20649-54. [PMID: 17034255 DOI: 10.1021/jp0630525] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Generation of functionally active biomolecular monolayers is important in both analytical science and biophysical analyses. Our ability to monitor the redox-active state of immobilized proteins or enzymes at a molecular level, from which stochastic and surface-induced variations would be apparent, is impeded by comparatively slow electron-transfer kinetics and associated signal:noise difficulties. We demonstrate herein that by covalently tethering an appropriate dye to the copper protein azurin a highly oxidation-state-sensitive FRET process can be established which enables redox switching to be optically monitored at protein levels down to the zeptomolar limit. The surface-potential-induced cycling of emission enables the redox potential of clusters of a few hundred molecules to be determined.
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Affiliation(s)
- J J Davis
- Central Research Laboratory, Mansfield Road, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
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40
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Shleev S, Wetterö J, Magnusson KE, Ruzgas T. Electrochemical characterization and application of azurin-modified gold electrodes for detection of superoxide. Biosens Bioelectron 2006; 22:213-9. [PMID: 16442792 DOI: 10.1016/j.bios.2005.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 12/01/2005] [Accepted: 12/20/2005] [Indexed: 10/25/2022]
Abstract
A novel biosensor for superoxide radical (O(2)(*-)) detection based on Pseudomonas aeruginosa azurin immobilized on gold electrode was designed. The rate constant of azurin reduction by O(2)(*-) was found to be 10(5)M(-1)s(-1) in solution and five times lower, i.e., 0.2 x 10(5)M(-1)s(-1), for azurin coupled to gold by 3,3'-dithiobis(sulfosuccinimidylpropionate) (DTSSP). The electron transfer rate between the protein and the electrode ranged from 2 to 6s(-1). The sensitivity of this biosensor to O(2)(*-) was 6.8 x 10(2)Am(-2)M(-1). The response to the interference substances, such as uric acid, H(2)O(2), and dimethylsulfoxide was negligible below 10 microM. The electrode was applied in three O(2)(*-) generating systems: (i) xanthine oxidase (XOD), (ii) potassium superoxide (KO(2)), and (iii) stimulated neutrophil granulocytes. The latter was compared with luminol-amplified chemiluminescence. The biosensor responded to O(2)(*-) in all three environments, and the signals were antagonized by superoxide dismutase.
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Affiliation(s)
- Sergey Shleev
- Biomedical Laboratory Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden.
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41
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Bonanni B, Bizzarri AR, Cannistraro S. Optimized Biorecognition of Cytochrome c 551 and Azurin Immobilized on Thiol-Terminated Monolayers Assembled on Au(111) Substrates. J Phys Chem B 2006; 110:14574-80. [PMID: 16869557 DOI: 10.1021/jp0610315] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular recognition between two redox partners, azurin and cytochrome c 551, is studied at the single-molecule level by means of atomic force spectroscopy, after optimizing azurin adsorption on gold via sulfhydryl-terminated alkanethiol spacers. Our experiments provide evidence of specific interaction between the two partners, thereby demonstrating that azurin preserves biorecognition capability when assembled on gold via these spacers. Additionally, the measured single-molecule kinetic reaction rate results are consistent with a likely transient nature of the complex. Interestingly, the immobilization strategy adopted here, which was previously demonstrated to favor electrical coupling between azurin (AZ) and the metal electrode, is also found to facilitate AZ interaction with the redox partner, if compared to the case of AZ directly adsorbed on bare gold. Our findings confirm the key role of a well-designed immobilization strategy, capable of optimizing both biorecognition capabilities and electrical coupling with the conductive substrate at the single-molecule level, as a starting point for advanced applications of redox proteins for ultrasensitive biosensing.
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Affiliation(s)
- B Bonanni
- Biophysics and Nanoscience Centre, CNISM, and CNR-INFM, Dipartimento di Scienze Ambientali, Università della Tuscia, Largo dell'Università, I-01100 Viterbo, Italy.
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42
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He X, Zhu L. Direct electrochemistry of hemoglobin in cetylpyridinium bromide film: Redox thermodynamics and electrocatalysis to nitric oxide. Electrochem commun 2006. [DOI: 10.1016/j.elecom.2006.02.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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43
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Davis JJ, Wang N, Morgan A, Zhang T, Zhao J. Metalloprotein tunnel junctions: compressional modulation of barrier height and transport mechanism. Faraday Discuss 2006; 131:167-79; discussion 205-20. [PMID: 16512371 DOI: 10.1039/b507854g] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Though the incorporation of sensory or potentially-switchable biological entities into electronic devices brings with it a number of complicating issues associated with hydration, structural complexity/delicacy, and low conductance, the possibility of resolving properties of fundamental importance (such as the influence of protein fold on conductance) at a molecularly-resolved level, are exciting. Our ability to analyse charge transport through a biological macromolecule remains, though, a significant practical and theoretical challenge. Though much information can be gained by carrying out such examinations at a molecular level, there exist few methods where such controlled analyses are, in fact, feasible. Here we report on the electron transport characteristics of a blue copper metalloprotein as characterized by conductive-probe atomic force microscopy. At very low imposed force, contact resistance is high, electrical contact unstable, and the junction undergoes dielectric breakdown at 1.1-1.5 GV m(-1). At increased applied force, the current-voltage characteristics are entirely reproducible and well-described by a Simmons (non-resonant) tunnelling model. Though highly resistive, observations demonstrate the ability of the protein matrix to mediate appreciable tunnelling current. Non-resonant behaviour is consistent with observations of bias-independent tunnelling imaging. In fitting observed transport characteristics to this model, it is possible to deconvolute barrier height and length at specific experimental conditions and, specifically, to monitor the modulation of these parameters by imposed compressional force. At higher field spectroscopic features assignable to metal based density of states are reproducibly observed. These vanish in a force regime where the tunnel barrier to direct tip-sample communication decreases.
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Affiliation(s)
- Jason J Davis
- Central Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3TA
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44
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Zhang J, Demetriou A, Welinder AC, Albrecht T, Nichols RJ, Ulstrup J. Potential-induced structural transitions of DL-homocysteine monolayers on Au(111) electrode surfaces. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2005.04.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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45
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Bonanni B, Kamruzzahan ASM, Bizzarri AR, Rankl C, Gruber HJ, Hinterdorfer P, Cannistraro S. Single molecule recognition between cytochrome C 551 and gold-immobilized azurin by force spectroscopy. Biophys J 2005; 89:2783-91. [PMID: 16192283 PMCID: PMC1366778 DOI: 10.1529/biophysj.105.064097] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent developments in single molecule force spectroscopy have allowed investigating the interaction between two redox partners, Azurin and Cytochrome C 551. Azurin has been directly chemisorbed on a gold electrode whereas cytochrome c has been linked to the atomic force microscopy tip by means of a heterobifunctional flexible cross-linker. When recording force-distance cycles, molecular recognition events could be observed, displaying unbinding forces of approximately 95 pN for an applied loading rate of 10 nN/s. The specificity of molecular recognition was confirmed by the significant decrease of unbinding probability observed in control block experiments performed adding free azurin solution in the fluid cell. In addition, the complex dissociation kinetics has been here investigated by monitoring the unbinding forces as a function of the loading rate: the thermal off-rate was estimated to be approximately 14 s(-1), much higher than values commonly estimated for complexes more stable than electron transfer complexes. Results here discussed represent the first studies on molecular recognition between two redox partners by atomic force microscopy.
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Affiliation(s)
- B Bonanni
- Istituto Nazionale Fisica della Materia-Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Dipartimento di Scienze Ambientali, Università della Tuscia, Viterbo, Italy.
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46
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Shleev S, Tkac J, Christenson A, Ruzgas T, Yaropolov AI, Whittaker JW, Gorton L. Direct electron transfer between copper-containing proteins and electrodes. Biosens Bioelectron 2005; 20:2517-54. [PMID: 15854824 DOI: 10.1016/j.bios.2004.10.003] [Citation(s) in RCA: 407] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 10/05/2004] [Accepted: 10/06/2004] [Indexed: 10/26/2022]
Abstract
The electrochemistry of some copper-containing proteins and enzymes, viz. azurin, galactose oxidase, tyrosinase (catechol oxidase), and the "blue" multicopper oxidases (ascorbate oxidase, bilirubin oxidase, ceruloplasmin, laccase) is reviewed and discussed in conjunction with their basic biochemical and structural characteristics. It is shown that long-range electron transfer between these enzymes and electrodes can be established, and the mechanistic schemes of the DET processes are proposed.
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Affiliation(s)
- Sergey Shleev
- Department of Analytical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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47
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Zhang J, Chi Q, Albrecht T, Kuznetsov AM, Grubb M, Hansen AG, Wackerbarth H, Welinder AC, Ulstrup J. Electrochemistry and bioelectrochemistry towards the single-molecule level: Theoretical notions and systems. Electrochim Acta 2005. [DOI: 10.1016/j.electacta.2004.12.044] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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48
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Electrochemical Impedance Biosensor for Glucose Detection Utilizing a Periplasmic E. coli Receptor Protein. ACTA ACUST UNITED AC 2005. [DOI: 10.1149/1.1943549] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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49
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50
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Wollenberger U. Chapter 2 Third generation biosensors—integrating recognition and transduction in electrochemical sensors. BIOSENSORS AND MODERN BIOSPECIFIC ANALYTICAL TECHNIQUES 2005. [DOI: 10.1016/s0166-526x(05)44002-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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