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Panagiotopoulos A, Gkouma A, Vassi A, Johnson CJ, Cass AEG, Topoglidis E. Hemin Modified SnO2
Films on ITO-PET with Enhanced Activity for Electrochemical Sensing. ELECTROANAL 2018. [DOI: 10.1002/elan.201800188] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Anthi Gkouma
- Department of Materials Science; University of Patras; Rion 26504 Greece
| | - Andriana Vassi
- Department of Materials Science; University of Patras; Rion 26504 Greece
| | - Christopher J. Johnson
- Department of Chemistry and Institute of Biomedical Engineering; Imperial College London; London SW7 2AZ UK
| | - Anthony E. G. Cass
- Department of Chemistry and Institute of Biomedical Engineering; Imperial College London; London SW7 2AZ UK
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2
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Ash PA, Hidalgo R, Vincent KA. Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase. J Vis Exp 2017:55858. [PMID: 29286464 PMCID: PMC5755520 DOI: 10.3791/55858] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Understanding the chemistry of redox proteins demands methods that provide precise control over redox centers within the protein. The technique of protein film electrochemistry, in which a protein is immobilized on an electrode surface such that the electrode replaces physiological electron donors or acceptors, has provided functional insight into the redox reactions of a range of different proteins. Full chemical understanding requires electrochemical control to be combined with other techniques that can add additional structural and mechanistic insight. Here we demonstrate a technique, protein film infrared electrochemistry, which combines protein film electrochemistry with infrared spectroscopic sampling of redox proteins. The technique uses a multiple-reflection attenuated total reflectance geometry to probe a redox protein immobilized on a high surface area carbon black electrode. Incorporation of this electrode into a flow cell allows solution pH or solute concentrations to be changed during measurements. This is particularly powerful in addressing redox enzymes, where rapid catalytic turnover can be sustained and controlled at the electrode allowing spectroscopic observation of long-lived intermediate species in the catalytic mechanism. We demonstrate the technique with experiments on E. coli hydrogenase 1 under turnover (H2 oxidation) and non-turnover conditions.
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Affiliation(s)
- Philip A Ash
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory
| | - Ricardo Hidalgo
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory
| | - Kylie A Vincent
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory;
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3
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Ash P, Reeve HA, Quinson J, Hidalgo R, Zhu T, McPherson IJ, Chung MW, Healy AJ, Nayak S, Lonsdale TH, Wehbe K, Kelley CS, Frogley MD, Cinque G, Vincent KA. Synchrotron-Based Infrared Microanalysis of Biological Redox Processes under Electrochemical Control. Anal Chem 2016; 88:6666-71. [PMID: 27269716 PMCID: PMC4935962 DOI: 10.1021/acs.analchem.6b00898] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/07/2016] [Indexed: 11/30/2022]
Abstract
We describe a method for addressing redox enzymes adsorbed on a carbon electrode using synchrotron infrared microspectroscopy combined with protein film electrochemistry. Redox enzymes have high turnover frequencies, typically 10-1000 s(-1), and therefore, fast experimental triggers are needed in order to study subturnover kinetics and identify the involvement of transient species important to their catalytic mechanism. In an electrochemical experiment, this equates to the use of microelectrodes to lower the electrochemical cell constant and enable changes in potential to be applied very rapidly. We use a biological cofactor, flavin mononucleotide, to demonstrate the power of synchrotron infrared microspectroscopy relative to conventional infrared methods and show that vibrational spectra with good signal-to-noise ratios can be collected for adsorbed species with low surface coverages on microelectrodes with a geometric area of 25 × 25 μm(2). We then demonstrate the applicability of synchrotron infrared microspectroscopy to adsorbed proteins by reporting potential-induced changes in the flavin mononucleotide active site of a flavoenzyme. The method we describe will allow time-resolved spectroscopic studies of chemical and structural changes at redox sites within a variety of proteins under precise electrochemical control.
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Affiliation(s)
- Philip
A. Ash
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Holly A. Reeve
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Jonathan Quinson
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Ricardo Hidalgo
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Tianze Zhu
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Ian J. McPherson
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Min-Wen Chung
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Adam J. Healy
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Simantini Nayak
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Thomas H. Lonsdale
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
| | - Katia Wehbe
- Diamond
Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Chris S. Kelley
- Diamond
Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Mark D. Frogley
- Diamond
Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Gianfelice Cinque
- Diamond
Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Kylie A. Vincent
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QR, United Kingdom
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4
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Vibrational Spectroscopic Techniques for Probing Bioelectrochemical Systems. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 158:75-110. [DOI: 10.1007/10_2016_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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5
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McMillan DGG, Marritt SJ, Kemp GL, Gordon-Brown P, Butt JN, Jeuken LJC. The Impact of Enzyme Orientation and Electrode Topology on the Catalytic Activity of Adsorbed Redox Enzymes. Electrochim Acta 2013; 110:79-85. [PMID: 24634538 DOI: 10.1016/j.electacta.2013.01.153] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
It is well established that the structural details of electrodes and their interaction with adsorbed enzyme influences the interfacial electron transfer rate. However, for nanostructured electrodes, it is likely that the structure also impacts on substrate flux near the adsorbed enzymes and thus catalytic activity. Furthermore, for enzymes converting macro-molecular substrates it is possible that the enzyme orientation determines the nature of interactions between the adsorbed enzyme and substrate and therefore catalytic rates. In essence the electrode may impede substrate access to the active site of the enzyme. We have tested these possibilities through studies of the catalytic performance of two enzymes adsorbed on topologically distinct electrode materials. Escherichia coli NrfA, a nitrite reductase, was adsorbed on mesoporous, nanocrystalline SnO2 electrodes. CymA from Shewanella oneidensis MR-1 reduces menaquinone-7 within 200 nm sized liposomes and this reaction was studied with the enzyme adsorbed on SAM modified ultra-flat gold electrodes.
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Affiliation(s)
- Duncan G G McMillan
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom. ; School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sophie J Marritt
- Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. ; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Gemma L Kemp
- Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. ; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Piers Gordon-Brown
- Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. ; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Julea N Butt
- Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. ; School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. ; School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Lars J C Jeuken
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom. ; School of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
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6
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Bioelectrocatalysis at mesoporous antimony doped tin oxide electrodes—Electrochemical characterization and direct enzyme communication. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.03.144] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Freely diffusing versus adsorbed protein: Which better mimics the cellular state of a redox protein? Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.03.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Manjula P, Boppella R, Manorama SV. A facile and green approach for the controlled synthesis of porous SnO₂ nanospheres: application as an efficient photocatalyst and an excellent gas sensing material. ACS APPLIED MATERIALS & INTERFACES 2012; 4:6252-60. [PMID: 23088260 DOI: 10.1021/am301840s] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A facile and elegant methodology invoking the principles of Green Chemistry for the synthesis of porous tin dioxide nanospheres has been described. The low-temperature (∼50 °C) synthesis of SnO₂ nanoparticles and their self-assembly into organized, uniform, and monodispersed porous nanospheres with high surface area is facilitated by controlling the concentration of glucose, which acts as a stabilizing as well as structure-directing agent. A systematic control on the stannate to glucose molar concentration ratio determines the exact conditions to obtain monodispersed nanospheres, preferentially over random aggregation. Detailed characterization of the structure, morphology, and chemical composition reveals that the synthesized material, 50 nm SnO₂ porous nanospheres possess BET surface area of about 160 m²/g. Each porous nanosphere consists of a few hundred nanoparticles ∼2-3 nm in diameter with tetragonal cassiterite crystal structure. The SnO₂ nanospheres exhibit elevated photocatalytic activity toward methyl orange with good recyclability. Because of the high activity and stability of this photocatalyst, the material is ideal for applications in environmental remediation. Moreover, SnO₂ nanospheres display excellent gas sensing capabilities toward hydrogen. Surface modification of the nanospheres with Pd transforms this sensing material into a highly sensitive and selective room-temperature hydrogen sensor.
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Affiliation(s)
- P Manjula
- Nanomaterials Laboratory, Inorganic & Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad-500007, Andhra Pradesh, India
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9
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Bradley JM, Marritt SJ, Kihlken MA, Haynes K, Hemmings AM, Berks BC, Cheesman MR, Butt JN. Redox and chemical activities of the hemes in the sulfur oxidation pathway enzyme SoxAX. J Biol Chem 2012; 287:40350-9. [PMID: 23060437 DOI: 10.1074/jbc.m112.396192] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND SoxAX enzymes initiate microbial oxidation of reduced inorganic sulfur compounds. Their catalytic mechanism is unknown. RESULTS Cyanide displaces the CysS(-) ligand to the active site heme following reduction by S(2)O(4)(2-) but not Eu(II). CONCLUSION An active site heme ligand becomes labile on exposure to substrate analogs. SIGNIFICANCE Elucidation of SoxAX mechanism is necessary to understand a widespread pathway for sulfur compound oxidation. SoxAX enzymes couple disulfide bond formation to the reduction of cytochrome c in the first step of the phylogenetically widespread Sox microbial sulfur oxidation pathway. Rhodovulum sulfidophilum SoxAX contains three hemes. An electrochemical cell compatible with magnetic circular dichroism at near infrared wavelengths has been developed to resolve redox and chemical properties of the SoxAX hemes. In combination with potentiometric titrations monitored by electronic absorbance and EPR, this method defines midpoint potentials (E(m)) at pH 7.0 of approximately +210, -340, and -400 mV for the His/Met, His/Cys(-), and active site His/CysS(-)-ligated heme, respectively. Exposing SoxAX to S(2)O(4)(2-), a substrate analog with E(m) ~-450 mV, but not Eu(II) complexed with diethylene triamine pentaacetic acid (E(m) ~-1140 mV), allows cyanide to displace the cysteine persulfide (CysS(-)) ligand to the active site heme. This provides the first evidence for the dissociation of CysS(-) that has been proposed as a key event in SoxAX catalysis.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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Schaming D, Renault C, Tucker RT, Lau-Truong S, Aubard J, Brett MJ, Balland V, Limoges B. Spectroelectrochemical characterization of small hemoproteins adsorbed within nanostructured mesoporous ITO electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:14065-14072. [PMID: 22957653 DOI: 10.1021/la302913j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
3D nanostructured transparent indium tin oxide (ITO) electrodes prepared by glancing angle deposition (GLAD) were used for the spectroelectrochemical characterization of cytochrome c (Cyt c) and neuroglobin (Nb). These small hemoproteins, involved as electron-transfer partners in the prevention of apoptosis, are oppositely charged at physiological pH and can each be adsorbed within the ITO network under different pH conditions. The resulting modified electrodes were investigated by UV-visible absorption spectroscopy coupled with cyclic voltammetry. By using nondenaturating adsorption conditions, we demonstrate that both proteins are capable of direct electron transfer to the conductive ITO surface, sharing apparent standard potentials similar to those reported in solution. Preservation of the 3D protein structure upon adsorption was confirmed by resonance Raman (rR) spectroscopy. Analysis of the derivative cyclic voltabsorptograms (DCVA) monitored either in the Soret or the Q bands at scan rates up to 1 V s(-1) allowed us to investigate direct interfacial electron transfer kinetics. From the DCVA shape and scan rate dependences, we conclude that the interaction of Cyt c with the ITO surface is more specific than Nb, suggesting an oriented adsorption of Cyt c and a random adsorption of Nb on the ITO surface. At the same time, Cyt c appears more sensitive to the experimental adsorption conditions, and complete denaturation of Cyt c may occur as evidenced from cross-correlation of rR spectroscopy and spectroelectrochemistry.
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Affiliation(s)
- Delphine Schaming
- Laboratoire d'Electrochimie Moléculaire, UMR CNRS 7591, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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11
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Renault C, Andrieux CP, Tucker RT, Brett MJ, Balland V, Limoges B. Unraveling the mechanism of catalytic reduction of O2 by microperoxidase-11 adsorbed within a transparent 3D-nanoporous ITO film. J Am Chem Soc 2012; 134:6834-45. [PMID: 22448869 DOI: 10.1021/ja301193s] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nanoporous films of indium tin oxide (ITO), with thicknesses ranging from 250 nm to 2 μm, were prepared by Glancing Angle Deposition (GLAD) and used as highly sensitive transparent 3D-electrodes for quantitatively interrogating, by time-resolved spectroelectrochemistry, the reactivity of microperoxidase-11 (MP-11) adsorbed within such films. The capacitive current densities of these 3D-electrodes as well as the amount of adsorbed MP-11 were shown to be linearly correlated to the GLAD ITO film thickness, indicating a homogeneous distribution of MP-11 across the film as well as homogeneous film porosity. Under saturating adsorption conditions, MP-11 film concentration as high as 60 mM was reached. This is equivalent to a stack of 110 monolayers of MP-11 per micrometer film thickness. This high MP-11 film loading combined with the excellent ITO film conductivity has allowed the simultaneous characterization of the heterogeneous one-electron transfer dynamics of the MP-11 Fe(III)/Fe(II) redox couple by cyclic voltammetry and cyclic voltabsorptometry, up to a scan rate of few volts per second with a satisfactory single-scan signal-to-noise ratio. The potency of the method to unravel complex redox coupled chemical reactions was also demonstrated with the catalytic reduction of oxygen by MP-11. In the presence of O(2), cross-correlation of electrochemical and spectroscopic data has allowed us to determine the key kinetics and thermodynamics parameters of the redox catalysis that otherwise could not be easily extracted using conventional protein film voltammetry. On the basis of numerical simulations of cyclic voltammograms and voltabsorptograms and within the framework of different plausible catalytic reaction schemes including appropriate approximations, it was shown possible to discriminate between different possible catalytic pathways and to identify the relevant catalytic cycle. In addition, from the best fits of simulations to the experimental voltammograms and voltabsorptograms, the partition coefficient of O(2) for the ITO film as well as the values of two kinetic rate constants could be extracted. It was finally concluded that the catalytic reduction of O(2) by MP-11 adsorbed within nanoporous ITO films occurs via a 2-electron mechanism with the formation of an intermediate Fe(III)-OOH adduct characterized by a decay rate of 11 s(-1). The spectroelectroanalytical strategy presented here opens new opportunities for characterizing complex redox-coupled chemical reactions not only with redox proteins, but also with redox biomimetic systems and catalysts. It might also be of great interest for the development and optimization of new spectroelectrochemical sensors and biosensors, or eventually new photoelectrocatalytic systems or biofuel cells.
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Affiliation(s)
- Christophe Renault
- Laboratoire d'Electrochimie Moléculaire, UMR CNRS 7591, Université Paris Diderot, Sorbonne Paris Cité, 15 rue Jean-Antoine de Baïf, F-75205 Paris Cedex 13, France
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12
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Electrochemical titrations and reaction time courses monitored in situ by magnetic circular dichroism spectroscopy. Anal Biochem 2011; 419:110-6. [DOI: 10.1016/j.ab.2011.07.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 07/24/2011] [Accepted: 07/25/2011] [Indexed: 11/19/2022]
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13
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Ash PA, Vincent KA. Spectroscopic analysis of immobilised redox enzymes under direct electrochemical control. Chem Commun (Camb) 2011; 48:1400-9. [PMID: 22057715 DOI: 10.1039/c1cc15871f] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article reviews recent developments in spectroscopic analysis of electrode-immobilised enzymes under direct, unmediated electrochemical control. These methods unite the suite of spectroscopic methods available for characterisation of structural, electronic and coordination changes in proteins with the exquisite control over complex redox enzymes that can be achieved in protein film electrochemistry in which immobilised protein molecules exchange electrons directly with an electrode. This combination is particularly powerful in studies of highly active enzymes where redox states can be controlled even under fast electrocatalytic turnover. We examine examples in which UV-visible, IR, Raman and MCD spectroscopy have been combined with direct electrochemistry to probe redox-dependent chemistry, and consider future opportunities for 'direct' spectroelectrochemistry of immobilised enzymes.
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Affiliation(s)
- Philip A Ash
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
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14
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Kepplinger C, Lisdat F, Wollenberger U. Cytochrome c/polyelectrolyte multilayers investigated by E-QCM-D: effect of temperature on the assembly structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8309-8315. [PMID: 21634413 DOI: 10.1021/la200860p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Protein multilayers, consisting of cytochrome c (cyt c) and poly(aniline sulfonic acid) (PASA), are investigated by electrochemical quartz crystal microbalance with dissipation monitoring (E-QCM-D). This technique reveals that a four-bilayer assembly has rather rigid properties. A thickness of 16.3 ± 0.8 nm is calculated with the Sauerbrey equation and is found to be in good agreement with a viscoelastic model. The electroactive amount of cyt c is estimated by the deposited mass under the assumption of 50% coupled water. Temperature-induced stabilization of the multilayer assembly has been investigated in the temperature range between 30 and 45 °C. The treatment results in a loss of material and a contraction of the film. The electroactive amount of cyt c also decreases during heating and remains constant after the cooling period. The contraction of the film is accompanied by the enhanced stability of the assembly. In addition, it is found that cyt c and PASA can be assembled at higher temperatures, resulting in the formation of multilayer systems with less dissipation.
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Affiliation(s)
- Christian Kepplinger
- Biosystems Technology, Wildau University of Applied Science, Bahnhofstrasse 1, 15745 Wildau, Germany
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15
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Chandra D, Bekki M, Nakamura M, Sonezaki S, Ohji T, Kato K, Kimura T. Dye-sensitized biosystem sensing using macroporous semiconducting metal oxide films. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm04347h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Chandra D, Ohji T, Kato K, Kimura T. Connectivity of PS-b-PEO templated spherical pores in titanium oxide films. Phys Chem Chem Phys 2011; 13:12529-35. [DOI: 10.1039/c1cp21060b] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Renault C, Harris KD, Brett MJ, Balland V, Limoges B. Time-resolved UV-visible spectroelectrochemistry using transparent 3D-mesoporous nanocrystalline ITO electrodes. Chem Commun (Camb) 2010; 47:1863-5. [PMID: 21127815 DOI: 10.1039/c0cc04154h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficient and rapid adsorption of microperoxidase 11 within a highly porous ITO thin film (200 nm) prepared by glancing angle deposition was achieved. Adsorbed redox molecules were reversibly and rapidly reduced throughout the 3D-conductive matrix in ca. 50 ms, allowing the heterogeneous electron transfer rate to be determined by derivative cyclic voltabsorptometry.
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Affiliation(s)
- Christophe Renault
- Laboratoire d'Electrochimie Moléculaire, Université Paris Diderot, UMR CNRS 7591, 15, rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
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18
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Abstract
Now, more than ever, enzymology and its development can be considered of vital importance to the progression of the biological sciences. With an increase in the numbers of enzymes being identified from genomic studies, enzymology is key to defining the structural and functional properties of these enzymes in order to establish their mechanisms of action and how they fit into metabolic networks. Along with the efforts of the bioinformaticians and systems biologists, such studies will ultimately lead to detailed descriptions of intricate biochemical pathways and allow identification of the most appropriate target enzymes for intervention in disease therapy. Thus the timing for the recent Biochemical Society Focused Meeting entitled 'Enzyme Mechanisms: Fast Reaction and Computational Approaches' was highly appropriate. The present paper represents an overview of this meeting, which was held at the Manchester Interdisciplinary Biocentre on 9-10 October 2008.
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Renault C, Balland V, Martinez-Ferrero E, Nicole L, Sanchez C, Limoges B. Highly ordered transparent mesoporous TiO2 thin films: an attractive matrix for efficient immobilization and spectroelectrochemical characterization of cytochrome c. Chem Commun (Camb) 2009:7494-6. [DOI: 10.1039/b919976d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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