1
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Wei J, Bloom BP, Dunlap-Shohl WA, Clever CB, Rivas JE, Waldeck DH. Examining the Effects of Homochirality for Electron Transfer in Protein Assemblies. J Phys Chem B 2023; 127:6462-6469. [PMID: 37463031 PMCID: PMC10388353 DOI: 10.1021/acs.jpcb.3c02913] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Protein voltammetry studies of cytochrome c, immobilized on chiral tripeptide monolayer films, reveal the importance of the electron spin and the film's homochirality on electron transfer kinetics. Magnetic film electrodes are used to examine how an asymmetry in the standard heterogeneous electron transfer rate constant arises from changes in the electron spin direction and the enantiomer composition of the tripeptide monolayer; rate constant asymmetries as large as 60% are observed. These findings are rationalized in terms of the chiral induced spin selectivity effect and spin-dependent changes in electronic coupling. Lastly, marked differences in the average rate constant are shown between homochiral ensembles, in which the peptide and protein possess the same enantiomeric form, compared to heterochiral ensembles, where the handedness of the peptide layer is opposite to that of the protein or itself comprises heterochiral building blocks. These data demonstrate a compelling rationale for why nature is homochiral; namely, spin alignment in homochiral systems enables more efficient energy transduction.
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Affiliation(s)
- Jimeng Wei
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Brian P Bloom
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Wiley A Dunlap-Shohl
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Caleb B Clever
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - José E Rivas
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - David H Waldeck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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2
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Pilz F, Kielb P. Cyclic voltammetry, square wave voltammetry or electrochemical impedance spectroscopy? Interrogating electrochemical approaches for the determination of electron transfer rates of immobilized redox proteins. BBA ADVANCES 2023; 4:100095. [PMID: 37424628 PMCID: PMC10322675 DOI: 10.1016/j.bbadva.2023.100095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 07/11/2023] Open
Abstract
In this article, we cross-examine three well-established electrochemical approaches, namely cyclic voltammetry (CV), cyclic square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) to dissect the electron transfer (ET) rate of electrostatically immobilized cytochrome c on Ag electrodes. A detailed analysis supported by simulations of redox transition provided three distinct values for the heterogeneous electron transfer (HET) rate constant of cyt c interfaced on COOH-terminated C10-long alkanethiol, i.e., kHET= 47.8 (±2,91) s-1 in CV, kHET= 64.8 (±1,27) s-1 in SWV, and kHET= 26.5 s-1 in EIS. We discuss the obtained discrepancies obtained from electrochemical methods and compare them with the data from spectro-electrochemical experiments. A comprehensive selection list is created from which the most applicable approach can be chosen for studying proteins of interest. CV is most applicable to study the interfaced proteins exhibiting kHET of ca. 0.5 - 70 s-1, SWV is suitable for a broader range of kHET of 5 - 120 s-1 and EIS for kHET of 0.5 to 5 s-1 if alkanethiols are used as immobilization strategy.
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Affiliation(s)
- F.H. Pilz
- Transdisciplinary Research Area ‘Building Blocks of Matter and Fundamental Interactions (TRA Matter)’, University of Bonn, Bonn, Germany
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, Bonn 53115, Germany
| | - P. Kielb
- Transdisciplinary Research Area ‘Building Blocks of Matter and Fundamental Interactions (TRA Matter)’, University of Bonn, Bonn, Germany
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, Bonn 53115, Germany
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3
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Olloqui-Sariego JL, Pérez-Mejías G, Márquez I, Guerra-Castellano A, Calvente JJ, De la Rosa MA, Andreu R, Díaz-Moreno I. Electric field-induced functional changes in electrode-immobilized mutant species of human cytochrome c. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148570. [PMID: 35643148 DOI: 10.1016/j.bbabio.2022.148570] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/21/2022] [Accepted: 05/20/2022] [Indexed: 06/15/2023]
Abstract
Post-translational modifications and naturally occurring mutations of cytochrome c have been recognized as a regulatory mechanism to control its biology. In this work, we investigate the effect of such in vivo chemical modifications of human cytochrome c on its redox properties in the adsorbed state onto an electrode. In particular, tyrosines 48 and 97 have been replaced by the non-canonical amino acid p-carboxymethyl-L-phenylalanine (pCMF), thus mimicking tyrosine phosphorylation. Additionally, tyrosine 48 has been replaced by a histidine producing the natural Y48H pathogenic mutant. Thermodynamics and kinetics of the interfacial electron transfer of wild-type cytochrome c and herein produced variants, adsorbed electrostatically under different local interfacial electric fields, were determined by means of variable temperature cyclic film voltammetry. It is shown that non-native cytochrome c variants immobilized under a low interfacial electric field display redox thermodynamics and kinetics similar to those of wild-type cytochrome c. However, upon increasing the strength of the electric field, the redox thermodynamics and kinetics of the modified proteins markedly differ from those of the wild-type species. The mutations promote stabilization of the oxidized form and a significant increase in the activation enthalpy values that can be ascribed to a subtle distortion of the heme cofactor and/or difference of the amino acid rearrangements rather than to a coarse protein structural change. Overall, these results point to a combined effect of the single point mutations at positions 48 and 97 and the strength of electrostatic binding on the regulatory mechanism of mitochondrial membrane activity, when acting as a redox shuttle protein.
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Affiliation(s)
- José Luis Olloqui-Sariego
- Departamento de Química Física, Universidad de Sevilla, Profesor García González, 1, 41012 Sevilla, Spain
| | - Gonzalo Pérez-Mejías
- Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Américo Vespucio 49, 41092 Sevilla, (Spain)
| | - Inmaculada Márquez
- Departamento de Química Física, Universidad de Sevilla, Profesor García González, 1, 41012 Sevilla, Spain; Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Américo Vespucio 49, 41092 Sevilla, (Spain)
| | - Alejandra Guerra-Castellano
- Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Américo Vespucio 49, 41092 Sevilla, (Spain)
| | - Juan José Calvente
- Departamento de Química Física, Universidad de Sevilla, Profesor García González, 1, 41012 Sevilla, Spain
| | - Miguel A De la Rosa
- Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Américo Vespucio 49, 41092 Sevilla, (Spain)
| | - Rafael Andreu
- Departamento de Química Física, Universidad de Sevilla, Profesor García González, 1, 41012 Sevilla, Spain
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Américo Vespucio 49, 41092 Sevilla, (Spain).
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4
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Oviedo-Rouco S, Spedalieri C, Scocozza MF, Tomasina F, Tórtora V, Radi R, Murgida DH. Correlated electric field modulation of electron transfer parameters and the access to alternative conformations of multifunctional cytochrome c. Bioelectrochemistry 2022; 143:107956. [PMID: 34624727 DOI: 10.1016/j.bioelechem.2021.107956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/10/2021] [Accepted: 09/22/2021] [Indexed: 11/21/2022]
Abstract
Cytochrome c (Cytc) is a multifunctional protein that, in its native conformation, shuttles electrons in the mitochondrial respiratory chain. Conformational transitions that involve replacement of the heme distal ligand lead to the gain of alternative peroxidase activity, which is crucial for membrane permeabilization during apoptosis. Using a time-resolved SERR spectroelectrochemical approach, we found that the key physicochemical parameters that characterize the electron transfer (ET) canonic function and those that determine the transition to alternative conformations are strongly correlated and are modulated by local electric fields (LEF) of biologically meaningful magnitude. The electron shuttling function is optimized at moderate LEFs of around 1 V nm-1. A decrease of the LEF is detrimental for ET as it rises the reorganization energy. Moreover, LEF values below and above the optimal for ET favor alternative conformations with peroxidase activity and downshifted reduction potentials. The underlying proposed mechanism is the LEF modulation of the flexibility of crucial protein segments, which produces a differential effect on the kinetic ET and conformational parameters of Cytc. These findings might be related to variations in the mitochondrial membrane potential during apoptosis, as the basis for the switch between canonic and alternative functions of Cytc. Moreover, they highlight the possible role of variable LEFs in determining the function of other moonlighting proteins through modulation of the protein dynamics.
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Affiliation(s)
- Santiago Oviedo-Rouco
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Cecilia Spedalieri
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Magalí F Scocozza
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Florencia Tomasina
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - Verónica Tórtora
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - Rafael Radi
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - Daniel H Murgida
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina.
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5
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Ghithan JH, Moreno M, Keynton RS, O'Toole MG, Mendes SB. Adsorption Properties and Electron-transfer Rates of a Redox Probe at Different Interfaces of an Immunoassay Assembled on an Electro-active Photonic Platform. ANAL SCI 2021; 37:1391-1399. [PMID: 33896878 DOI: 10.2116/analsci.21p010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Physical and chemical properties of a redox protein adsorbed to different interfaces of a multilayer immunoassay assembly were studied using a single-mode, electro-active, integrated optical waveguide (SM-EA-IOW) platform. For each interface of the immunoassay assembly (indium tin oxide, 3-aminopropyl triethoxysilane, recombinant protein G, antibody, and bovine serum albumin) the surface density, the adsorption kinetics, and the electron-transfer rate of bound species of the redox-active cytochrome c (Cyt-C) protein were accurately quantified at very low surface concentrations of redox species (from 0.4 to 4% of a full monolayer) using a highly sensitive optical impedance spectroscopy (OIS) technique based on measurements obtained with the SM-EA-IOW platform. The technique is shown here to provide quantitative insights into an important immunoassay assembly for characterization and understanding of the mechanisms of electron transfer rate, the affinity strength of molecular binding, and the associated bio-selectivity. Such methodology and acquired knowledge are crucial for the development of novel and advanced immuno-biosensors.
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Affiliation(s)
- Jafar H Ghithan
- Department of Physics and Astronomy, University of Louisville
| | - Monica Moreno
- Department of Bioengineering, University of Louisville
| | | | | | - Sergio B Mendes
- Department of Physics and Astronomy, University of Louisville
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6
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Chattopadhyay S, Mukherjee M, Kandemir B, Bowman SEJ, Bren KL, Dey A. Contributions to cytochrome c inner- and outer-sphere reorganization energy. Chem Sci 2021; 12:11894-11913. [PMID: 34659730 PMCID: PMC8442690 DOI: 10.1039/d1sc02865k] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/05/2021] [Indexed: 11/21/2022] Open
Abstract
Cytochromes c are small water-soluble proteins that catalyze electron transfer in metabolism and energy conversion processes. Hydrogenobacter thermophilus cytochrome c552 presents a curious case in displaying fluxionality of its heme axial methionine ligand; this behavior is altered by single point mutation of the Q64 residue to N64 or V64, which fixes the ligand in a single configuration. The reorganization energy (λ) of these cytochrome c552 variants is experimentally determined using a combination of rotating disc electrochemistry, chronoamperometry and cyclic voltammetry. The differences between the λ determined from these complementary techniques helps to deconvolute the contribution of the active site and its immediate environment to the overall λ (λTotal). The experimentally determined λ values in conjunction with DFT calculations indicate that the differences in λ among the protein variants are mainly due to the differences in contributions from the protein environment and not just inner-sphere λ. DFT calculations indicate that the position of residue 64, responsible for the orientation of the axial methionine, determines the geometric relaxation of the redox active molecular orbital (RAMO). The orientation of the RAMO with respect to the heme is key to determining electron transfer coupling (HAB) which results in higher ET rates in the wild-type protein relative to the Q64V mutant despite a 150 mV higher λTotal in the former. Efficient delocalization of the redox-active molecular orbital (RAMO) in HtWT results in an increase in HAB value which in turn accelerates the electron transfer (ET) rate in spite of the higher reorganization energy (λ) than the HtQ64V mutant.![]()
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Affiliation(s)
- Samir Chattopadhyay
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A Raja SC Mullick Road Kolkata WB 700032 India
| | - Manjistha Mukherjee
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A Raja SC Mullick Road Kolkata WB 700032 India
| | - Banu Kandemir
- Department of Chemistry, University of Rochester Rochester NY 14627-0216 USA
| | - Sarah E J Bowman
- Department of Chemistry, University of Rochester Rochester NY 14627-0216 USA
| | - Kara L Bren
- Department of Chemistry, University of Rochester Rochester NY 14627-0216 USA
| | - Abhishek Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A Raja SC Mullick Road Kolkata WB 700032 India
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7
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Murgida DH. In Situ Spectroelectrochemical Investigations of Electrode-Confined Electron-Transferring Proteins and Redox Enzymes. ACS OMEGA 2021; 6:3435-3446. [PMID: 33585730 PMCID: PMC7876673 DOI: 10.1021/acsomega.0c05746] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/19/2021] [Indexed: 06/09/2023]
Abstract
This perspective analyzes recent advances in the spectroelectrochemical investigation of redox proteins and enzymes immobilized on biocompatible or biomimetic electrode surfaces. Specifically, the article highlights new insights obtained by surface-enhanced resonance Raman (SERR), surface-enhanced infrared absorption (SEIRA), protein film infrared electrochemistry (PFIRE), polarization modulation infrared reflection-absorption spectroscopy (PMIRRAS), Förster resonance energy transfer (FRET), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and differential electrochemical mass spectrometry (DMES)-based spectroelectrochemical methods on the structure, orientation, dynamics, and reaction mechanisms for a variety of immobilized species. This includes small heme and copper electron shuttling proteins, large respiratory complexes, hydrogenases, multicopper oxidases, alcohol dehydrogenases, endonucleases, NO-reductases, and dye decolorizing peroxidases, among other enzymes. Finally, I discuss the challenges and foreseeable future developments toward a better understanding of the functioning of these complex macromolecules and their exploitation in technological devices.
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Affiliation(s)
- Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química-Física,
Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos
Aires 1428, Argentina
- Instituto
de Química Física de los Materiales, Medio Ambiente
y Energía (INQUIMAE), CONICET-Universidad de Buenos Aires, Buenos Aires C1428EHA, Argentina
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8
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Ion transfer channel network formed by flower and rod shape crystals of hair hydrolysate in poly(vinyl alcohol) matrix and its application as anion exchange membrane in fuel cells. J Colloid Interface Sci 2020; 587:214-228. [PMID: 33360894 DOI: 10.1016/j.jcis.2020.12.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/13/2020] [Accepted: 12/05/2020] [Indexed: 11/21/2022]
Abstract
Ion transfer phenomena occurring in nature are known to be most efficient. Many efforts have been made to mimic such phenomena, especially in the area of energy transfer. Proteins consisting of various amino acids are known to be the fundamental materials behind these phenomena. In the current study, an effort was made to extract proteinaceous material from human hair bio-waste by a green chemical-free thermal hydrolysis process. A simple heat treatment of the human hairs in presence of water led to the formation of a water soluble material, which was called hair hydrolysate (HH), contains 70 wt% proteinaceous material. It was utilized for the fabrication of poly(vinyl alcohol) (PVA) matrix-based anion exchange membrane (AEM). Presence of 27 wt% charged amino acids and 19 wt% polarizable amino acids in the HH provided effective charge transfer sites. 7 wt% arginine present in the HH, having continuous delocalized net positive charge helped the membrane to be stable in highly alkaline conditions, which was confirmed by an indirect analysis of alkaline stability. Formation of rod and flower shaped crystal morphology by the HH in glutaraldehyde crosslinked PVA matrix, created a continuous channel network at higher loadings, which provided a simple path for ion transfer, achieving OH- conductivity of 7.46 mS/cm at 70 °C. Swelling of the PVA matrix was minimized by annealing of the HH loaded sample, which resulted in reduction of ionic conductivity to 6.16 mS/cm (at 70 °C). At the same time, improvement in the properties like increase in thermal, mechanical and thermo-mechanical stability, reduction in water uptake, %swelling and methanol permeability was observed. The selectivity of the membrane was increased to almost a decimal place. Thus, the HH obtained from simple green thermal hydrolysis of human hair bio-waste is a cheap material, which is found to be suitable as ion conductive material for alkaline fuel cells.
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9
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Pérez-Mejías G, Olloqui-Sariego JL, Guerra-Castellano A, Díaz-Quintana A, Calvente JJ, Andreu R, De la Rosa MA, Díaz-Moreno I. Physical contact between cytochrome c1 and cytochrome c increases the driving force for electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148277. [DOI: 10.1016/j.bbabio.2020.148277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/29/2020] [Accepted: 07/09/2020] [Indexed: 01/09/2023]
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10
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Yin Z, Ji Z, Zhang W, Taylor EW, Zeng X, Wei J. The Glucose Effect on Direct Electrochemistry and Electron Transfer Reaction of Glucose Oxidase Entrapped in a Carbon Nanotube‐Polymer Matrix. ChemistrySelect 2020. [DOI: 10.1002/slct.202003536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ziyu Yin
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
| | - Zuowei Ji
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
| | - Wendi Zhang
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
| | - E. Will Taylor
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
- Department of Chemistry University of North Carolina at Greensboro Greensboro NC 27402 USA
| | - Xinping Zeng
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
- School of Life Science and Technology Tongji University Shanghai China
| | - Jianjun Wei
- Department of Nanoscience Joint School of Nanoscience and Nanoengineering University of North Carolina at Greensboro Greensboro NC 27401 USA
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11
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Zitare UA, Szuster J, Santalla MC, Morgada MN, Vila AJ, Murgida DH. Dynamical effects in metalloprotein heterogeneous electron transfer. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.136095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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12
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Nioradze N, Dolidze T, Shushanian M, Khoshtariya D. The first observation of electrochemistry of graphene/cysteine/copper composite. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2019.113490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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13
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Goychuk I. Fractional electron transfer kinetics and a quantum breaking of ergodicity. Phys Rev E 2019; 99:052136. [PMID: 31212539 DOI: 10.1103/physreve.99.052136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Indexed: 06/09/2023]
Abstract
The dissipative curve-crossing problem provides a paradigm for electron-transfer (ET) processes in condensed media. It establishes the simplest conceptual test bed to study the influence of the medium's dynamics on ET kinetics both on the ensemble level, and on the level of single particles. Single electron description is particularly important for nanoscaled systems like proteins, or molecular wires. Especially insightful is this framework in the semiclassical limit, where the environment can be treated classically, and an exact analytical treatment becomes feasible. Slow medium's dynamics is capable of enslaving ET and bringing it on the ensemble level from a quantum regime of nonadiabatic tunneling to the classical adiabatic regime, where electrons follow the nuclei rearrangements. This classical adiabatic textbook picture contradicts, however, in a very spectacular fashion to the statistics of single electron transitions, even in the Debye, memoryless media, also named Ohmic in the parlance of the famed spin-boson model. On the single particle level, ET always remains quantum, and this was named a quantum breaking of ergodicity in the adiabatic ET regime. What happens in the case of subdiffusive, fractional, or sub-Ohmic medium's dynamics, which is featured by power-law decaying dynamical memory effects typical, e.g., for protein macromolecules, and other viscoelastic media? Such a memory is vividly manifested by anomalous Cole-Cole dielectric response in such media. We address this question based both on accurate numerics and analytical theory. The ensemble theory remarkably agrees with the numerical dynamics of electronic populations, revealing a power-law relaxation tail even in a profoundly nonadiabatic electron transfer regime. In other words, ET in such media should typically display fractional kinetics. However, a profound difference with the numerically accurate results occurs for the distribution of residence times in the electronic states, both on the ensemble level and the level of single trajectories. Ergodicity is broken dynamically even in a more spectacular way than in the memoryless case. Our results question the applicability of all the existing and widely accepted ensemble theories of electron transfer in fractional, sub-Ohmic environments, on the level of single molecules, and provide a real challenge to face, both for theorists and experimentalists.
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Affiliation(s)
- Igor Goychuk
- Institute for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24/25, 14476 Potsdam-Golm, Germany
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14
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Futera Z, Blumberger J. Adsorption of Amino Acids on Gold: Assessing the Accuracy of the GolP-CHARMM Force Field and Parametrization of Au-S Bonds. J Chem Theory Comput 2018; 15:613-624. [PMID: 30540462 DOI: 10.1021/acs.jctc.8b00992] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The interaction of amino acids with metal electrodes plays a crucial role in bioelectrochemistry and the emerging field of bionanoelectronics. Here we present benchmark calculations of the adsorption structure and energy of all natural amino acids on Au(111) in vacuum using a van-der-Waals density functional (revPBE-vdW) that showed good performance on the S22 set of weakly bound dimers (mean relative unsigned error (MRUE) wrt CCSD(T)/CBS = 13.3%) and adsorption energies of small organic molecules on Au(111) (MRUE wrt experiment = 11.2%). The vdW-DF results are then used to assess the accuracy of a popular force field for Au-amino acid interactions, GolP-CHARMM, which explicitly describes image charge interactions via rigid-rod dipoles. We find that while the force field underestimates adsorption distances, it does reproduce the binding energy rather well (MRUE wrt revPBE-vdW = 11.3%) with the MRUE decreasing in the order Cys, Met > amines > aliphatic > carboxylic > aromatic. We also present a parametrization of the bonding interaction between sulfur-containing molecules and the Au(111) surface and report force field parameters that are compatible with GolP-CHARMM. We believe the vdW-DF calculations presented herein will provide useful reference data for further force field development, and that the new Au-S bonding parameters will enable improved simulations of proteins immobilized on Au-electrodes via S-linkages.
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Affiliation(s)
- Zdenek Futera
- Department of Physics and Astronomy and Thomas-Young-Centre , University College London , Gower Street , London , WC1E 6BT , U.K
| | - Jochen Blumberger
- Department of Physics and Astronomy and Thomas-Young-Centre , University College London , Gower Street , London , WC1E 6BT , U.K.,Institute for Advanced Study , Technische Universität München , Lichtenbergstrasse 2 a , D-85748 Garching , Germany
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15
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Zeng Z, Wei J, Liu Y, Zhang W, Mabe T. Magnetoreception of Photoactivated Cryptochrome 1 in Electrochemistry and Electron Transfer. ACS OMEGA 2018; 3:4752-4759. [PMID: 31458694 PMCID: PMC6641772 DOI: 10.1021/acsomega.8b00645] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 04/23/2018] [Indexed: 06/10/2023]
Abstract
Cryptochromes are flavoproteins whose photochemistry is important for crucial functions associated with phototropism and circadian clocks. In this report, we, for the first time, observed a magnetic response of the cryptochrome 1 (CRY1) immobilized at a gold electrode with illumination of blue light. These results present the magnetic field-enhanced photoinduced electron transfer of CRY1 to the electrode by voltammetry, exhibiting magnetic responsive rate constant and electrical current changes. A mechanism of the electron transfer, which involves photoinduced radicals in the CRY, is sensitive to the weak magnetic field; and the long-lived free radical FAD•- is responsible for the detected electrochemical Faradaic current. As a photoreceptor, the finding of a 5.7% rate constant change in electron transfer corresponding to a 50 μT magnetic field may be meaningful in regulation of magnetic field signaling and circadian clock function under an electromagnetic field.
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16
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Mondal PC, Fontanesi C. Electrochemistry of Metalloproteins Attached through Functional Self-Assembled Monolayers on Gold and Ferromagnetic Electrodes. Chemphyschem 2017; 19:60-66. [PMID: 29124840 DOI: 10.1002/cphc.201701018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 10/28/2017] [Indexed: 11/08/2022]
Abstract
We report the experimental results of a study of the electron-transfer processes of redox-active metalloproteins bound to mixed self-assembled monolayers (SAMs) on magnetic (nickel or ultrathin gold-coated nickel) or nonmagnetic (gold) electrodes. Metalloproteins, such as hemoglobin (Hb), Cytochrome C (Cyt C), and Cyt C oxidase, are attached through electrostatic interactions to the free carboxylate or imidazole groups present in the mixed SAMs. The formation of both mixed SAMs and SAM/metalloprotein heterostructures were confirmed by using advanced surface analysis techniques, such as polarization modulation infrared reflection absorption spectroscopy and aqueous contact angle measurements. Electrochemical measurements indicated a stronger electronic coupling between Hb and Cyt C oxidase and the mixed-SAM-coated gold or gold-coated-nickel electrodes, whereas a weaker coupling was found between the protein and the pure nickel electrode. Surface coverage and the electron-transfer rate constant were estimated from the cyclic voltammetry data.
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Affiliation(s)
- Prakash Chandra Mondal
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel.,National Institute for Nanotechnology, University of Alberta, Edmonton, T6G 2M9, AB (Canada
| | - Claudio Fontanesi
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel.,DIEF, University of Modena and Reggio Emilia, Via Vivarelli 10, 41125, Modena, Italy
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17
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Zhu N, Ulstrup J, Chi Q. Long-range interfacial electron transfer and electrocatalysis of molecular scale Prussian Blue nanoparticles linked to Au(111)-electrode surfaces by different chemical contacting groups. RUSS J ELECTROCHEM+ 2017. [DOI: 10.1134/s1023193517100159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Alvarez-Paggi D, Hannibal L, Castro MA, Oviedo-Rouco S, Demicheli V, Tórtora V, Tomasina F, Radi R, Murgida DH. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog. Chem Rev 2017; 117:13382-13460. [DOI: 10.1021/acs.chemrev.7b00257] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Luciana Hannibal
- Department
of Pediatrics, Universitätsklinikum Freiburg, Mathildenstrasse 1, Freiburg 79106, Germany
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Santiago Oviedo-Rouco
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Veronica Demicheli
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Veronica Tórtora
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Florencia Tomasina
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Rafael Radi
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
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19
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Trashin S, Rahemi V, Ramji K, Neven L, Gorun SM, De Wael K. Singlet oxygen-based electrosensing by molecular photosensitizers. Nat Commun 2017. [PMCID: PMC5519987 DOI: 10.1038/ncomms16108] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes. Application of enzyme-based sensors is usually affected by costs, enzyme stability and immobilization and use of additional chemicals. Here, the authors show a cost-effective and robust photoelectrochemical detection system that can mimic enzymatic sensors using only air and light.
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20
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Wang Y, Wang H, Chen Y, Wang Y, Chen HY, Shan X, Tao N. Fast Electrochemical and Plasmonic Detection Reveals Multitime Scale Conformational Gating of Electron Transfer in Cytochrome c. J Am Chem Soc 2017; 139:7244-7249. [PMID: 28478669 DOI: 10.1021/jacs.7b00839] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Conformational fluctuations play a central role in the electron transfer reactions of molecules. Because the fluctuations can be extremely fast in kinetics and small in amplitude, a technique with fast temporal resolution and high conformational sensitivity is needed to follow the transient electron transfer processes. Here we report on an electrochemically controlled plasmonic detection technique capable of monitoring conformational changes in redox molecules with ns response time. Using the technique, we study the electron transfer reaction and the associated conformational gating of a redox protein (cytochrome c). The study reveals that the conformational gating takes place over a broad range of time scales, from microsecond to millisecond.
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Affiliation(s)
- Yan Wang
- Biodesign Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States
| | - Hui Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China
| | - Yuheng Chen
- Biodesign Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States
| | - Yixian Wang
- Department of Chemistry and Biochemistry, California State University, Los Angeles , Los Angeles, California 90032, United States
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China
| | - Xiaonan Shan
- Department of Electrical & Computer Engineering, University of Houston , Houston, Texas 77024, United States
| | - Nongjian Tao
- Biodesign Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States.,State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China
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21
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Muthuchamy N, Lee KP, Gopalan AI. Enhanced photoelectrochemical biosensing performances for graphene (2D) – Titanium dioxide nanowire (1D) heterojunction polymer conductive nanosponges. Biosens Bioelectron 2017; 89:390-399. [DOI: 10.1016/j.bios.2016.06.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/03/2016] [Accepted: 06/03/2016] [Indexed: 10/21/2022]
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22
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Zhang B, Xu J, Mo SF, Yao JX, Dai SY. Molecular dynamics simulations of the orientation properties of cytochrome c on the surface of single-walled carbon nanotubes. J Mol Model 2016; 22:300. [DOI: 10.1007/s00894-016-3164-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/08/2016] [Indexed: 11/30/2022]
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23
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24
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Szuwarzyński M, Wolski K, Zapotoczny S. Enhanced stability of conductive polyacetylene in ladder-like surface-grafted brushes. Polym Chem 2016. [DOI: 10.1039/c6py00977h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Formation and characterization of polyacetylene-based brushes that exhibit exceptional long term stability in air is presented here.
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Affiliation(s)
| | - Karol Wolski
- Jagiellonian University
- Faculty of Chemistry
- 30-060 Krakow
- Poland
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25
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Dolidze TD, Shushanyan M, Khoshtariya DE. Electron transfer with myoglobin in free and strongly confined regimes: disclosing diverse mechanistic role of the Fe-coordinated water by temperature- and pressure-assisted voltammetric studies. J COORD CHEM 2015. [DOI: 10.1080/00958972.2015.1068937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Tinatin D. Dolidze
- Department of Biophysics, I. Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
- Department of Physics, Institute for Biophysics and Bionanosciences, I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
- Department of Chemistry and Pharmacy, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - Mikhael Shushanyan
- Department of Biophysics, I. Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
- Department of Physics, Institute for Biophysics and Bionanosciences, I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - Dimitri E. Khoshtariya
- Department of Biophysics, I. Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
- Department of Physics, Institute for Biophysics and Bionanosciences, I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
- Department of Chemistry and Pharmacy, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany
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26
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Ly HK, Wrzolek P, Heidary N, Götz R, Horch M, Kozuch J, Schwalbe M, Weidinger IM. 2 nd coordination sphere controlled electron transfer of iron hangman complexes on electrodes probed by surface enhanced vibrational spectroscopy. Chem Sci 2015; 6:6999-7007. [PMID: 29861938 PMCID: PMC5947519 DOI: 10.1039/c5sc02560e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/04/2015] [Indexed: 12/14/2022] Open
Abstract
Surface enhanced vibrational spectroscopy shows the correlation between electron transfer kinetics and protonation degree of Fe Hangman complexes on electrodes.
Iron hangman complexes exhibit improved catalytic properties regarding O2 and H2O2 reduction, which are attributed to the presence of a proton donating group in defined vicinity of the catalytic metal centre. Surface enhanced resonance Raman (SERR) and IR (SEIRA) spectro-electrochemistry has been applied concomitantly for the first time to analyse such iron hangman porphyrin complexes attached to electrodes in aqueous solution. While the SERR spectra yield information about the redox state of the central iron, the SEIRA spectra show protonation and deprotonation events of the 2nd coordination sphere. To investigate the influence of a proton active hanging group on the heterogeneous electron transfer between the iron porphyrin and the electrode, two hangman complexes with either an acid or ester functional group were compared. Using time resolved SERR spectroscopy the electron transfer rates of both complexes were determined. Complexes with an acid group showed a slow electron transfer rate at neutral pH that increased significantly at pH 4, while complexes with an ester group exhibited a much faster, but pH independent rate. SEIRA measurements were able to determine directly for the first time a pKa value of 3.4 of a carboxylic hanging group in the immobilized state that shifted to 5.2 in D2O buffer solution. The kinetic data showed an increase of the heterogeneous electron transfer rate with the protonation degree of the acid groups. From these results, we propose a PCET which is strongly modulated by the protonation state of the acid hanging group via hydrogen bond interactions.
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Affiliation(s)
- H K Ly
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - P Wrzolek
- Department of Chemistry , Humboldt Universität zu Berlin , Brook-Taylor-Str. 2 , D-12489 Berlin , Germany .
| | - N Heidary
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - R Götz
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - M Horch
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - J Kozuch
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - M Schwalbe
- Department of Chemistry , Humboldt Universität zu Berlin , Brook-Taylor-Str. 2 , D-12489 Berlin , Germany .
| | - I M Weidinger
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
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27
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Salamifar SE, Lee S, Lai RY. Electrochemical hydrogen peroxide sensors fabricated using cytochrome c immobilized on macroelectrodes and ultramicroelectrodes. Colloids Surf B Biointerfaces 2014; 123:866-9. [DOI: 10.1016/j.colsurfb.2014.10.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 10/04/2014] [Accepted: 10/15/2014] [Indexed: 10/24/2022]
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28
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Daidone I, Amadei A, Zaccanti F, Borsari M, Bortolotti CA. How the Reorganization Free Energy Affects the Reduction Potential of Structurally Homologous Cytochromes. J Phys Chem Lett 2014; 5:1534-40. [PMID: 26270092 DOI: 10.1021/jz5005208] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Differences in the reduction potential E(0) among structurally similar metalloproteins cannot always be fully explained on the basis of their 3-D structures. We investigate the molecular determinants to E(0) using the mixed quantum mechanics/molecular mechanics approach named perturbed matrix method (PMM); after comparison with experimental values to assess the reliability of our calculations, we investigate the relationship between the change in free energy upon reduction ΔA(0) and the reorganization energy. We find that the reduction potential of cytochromes can be regarded as the result of the sum of two terms, one being mostly dependent on the energy fluctuations within a limited range around the mean transition energy and the second being mostly dependent linearly on the difference Δλ = λred - λox of the reorganization free energies for the ox → red (λred) and for the red → ox (λox) relaxations.
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Affiliation(s)
- Isabella Daidone
- †Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio (Coppito 1), 67010 L'Aquila, Italy
| | - Andrea Amadei
- ‡Department of Chemical Sciences and Technologies, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, 00133 Rome, Italy
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29
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Olloqui-Sariego JL, Moreno-Beltrán B, Díaz-Quintana A, De la Rosa MA, Calvente JJ, Andreu R. Temperature-Driven Changeover in the Electron-Transfer Mechanism of a Thermophilic Plastocyanin. J Phys Chem Lett 2014; 5:910-914. [PMID: 26274087 DOI: 10.1021/jz500150y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electron-transfer kinetics of the thermophilic protein Plastocyanin from Phormidium laminosum adsorbed on 1,ω-alkanedithiol self-assembled monolayers (SAMs) deposited on gold have been investigated. The standard electron-transfer rate constant has been determined as a function of electrode-protein distance and solution viscosity over a broad temperature range (0-90 °C). For either thin or thick SAMs, the electron-transfer regime remains invariant with temperature, whereas for the 1,11-undecanethiol SAM of intermediate chain length, a kinetic regime changeover from a gated or friction-controlled mechanism at low temperature (0-30 °C) to a nonadiabatic mechanism above 40 °C is observed. To the best of our knowledge, this is the first time a thermal-induced transition between these two kinetic regimes is reported for a metalloprotein.
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Affiliation(s)
- José Luis Olloqui-Sariego
- †Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain
| | - Blas Moreno-Beltrán
- ‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Antonio Díaz-Quintana
- ‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Miguel A De la Rosa
- ‡Instituto de Bioquı́mica Vegetal y Fotosı́ntesis, cicCartuja, Universidad de Sevilla y C.S.I.C, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Juan José Calvente
- †Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain
| | - Rafael Andreu
- †Departamento de Quı́mica Fı́sica, Universidad de Sevilla, c/Profesor Garcı́a González, 1, 41012 Sevilla, Spain
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30
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Khoshtariya DE, Dolidze TD, Shushanyan M, van Eldik R. Long-range electron transfer with myoglobin immobilized at Au/mixed-SAM junctions: mechanistic impact of the strong protein confinement. J Phys Chem B 2014; 118:692-706. [PMID: 24369906 DOI: 10.1021/jp4101569] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Horse muscle myoglobin (Mb) was tightly immobilized at Au-deposited ~15-Å-thick mixed-type (1:1) alkanethiol SAMs, HS-(CH₂)₁₁-COOH/HS-(CH₂)₁₁-OH, and placed in contact with buffered H₂O or D₂O solutions. Fast-scan cyclic voltammetry (CV) and a Marcus-equation-based analysis were applied to determine unimolecular standard rate constants and reorganization free energies for electron transfer (ET), under variable-temperature (15-55 °C) and -pressure (0.01-150 MPa) conditions. The CV signal was surprisingly stable and reproducible even after multiple temperature and pressure cycles. The data analysis revealed the following values: standard rate constant, 33 s⁻¹ (25 °C, 0.01 MPa, H₂O); reorganization free energy, 0.5 ± 0.1 eV (throughout); activation enthalpy, 12 ± 3 kJ mol⁻¹; activation volume, -3.1 ± 0.2 cm³ mol⁻¹; and pH-dependent solvent kinetic isotope effect (k(H)⁰/k(D)⁰), 0.7-1.4. Furthermore, the values for the rate constant and reorganization free energy are very similar to those previously found for cytochrome c electrostatically immobilized at the monocomponent Au/HS-(CH₂)₁₁-COOH junction. In vivo, Mb apparently forms a natural electrostatic complex with cytochrome b₅ (cyt-b₅) through the "dynamic" (loose) docking pattern, allowing for a slow ET that is intrinsically coupled to the water's removal from the "defective" heme iron (altogether shaping the biological repair mechanism for Mb's "met" form). In contrary, our experiments rather mimic the case of a "simple" (tight) docking of the redesigned (mutant) Mb with cyt-b₅ (Nocek et al. J. Am. Chem. Soc. 2010, 132, 6165-6175). According to our analysis, in this configuration, Mb's distal pocket (linked to the "ligand channel") seems to be arrested within the restricted configuration, allowing the rate-determining reversible ET process to be coupled only to the inner-sphere reorganization (minimal elongation/shortening of an Fe-OH₂ bond) rather than the pronounced detachment (rebinding) of water and, hence, to be much faster.
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Affiliation(s)
- Dimitri E Khoshtariya
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg , 91058 Erlangen, Germany
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31
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Kuzume A, Zhumaev U, Li J, Fu Y, Füeg M, Esteve-Nuñez A, Wandlowski T. An in-situ surface electrochemistry approach toward whole-cell studies: Charge transfer between Geobacter sulfurreducens and electrified metal/electrolyte interfaces through linker molecules. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.02.073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Alizadeh V, Mehrgardi MA, Fazlollah Mousavi M. Electrochemical Investigation of Cytochrome c Immobilized onto Self-Assembled Monolayer of Captopril. ELECTROANAL 2013. [DOI: 10.1002/elan.201300036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Tretyakova T, Shushanyan M, Partskhaladze T, Makharadze M, van Eldik R, Khoshtariya DE. Simplicity within the complexity: bilateral impact of DMSO on the functional and unfolding patterns of α-chymotrypsin. Biophys Chem 2013; 175-176:17-27. [PMID: 23524288 DOI: 10.1016/j.bpc.2013.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 02/05/2013] [Accepted: 02/09/2013] [Indexed: 10/27/2022]
Abstract
New understanding of the fundamental links between protein stability, conformational flexibility and function, can be gained through synergic studies on their catalytic and folding/unfolding properties under the influence of stabilizing/destabilizing additives. We explored an impact of dimethyl sulfoxide (DMSO), the moderate effector of multilateral action, on the kinetic (functional) and thermodynamic (thermal unfolding) patterns of a hydrolytic enzyme, α-chymotrypsin (α-CT), over a wide range of additive concentrations, 0-70% (v/v). Both the calorimetric and kinetic data exhibited rich behavior pointing to the complex interplay of global/local stability (and flexibility) patterns. The complex action of DMSO is explained through the negative and positive preferential solvation motifs that prevail for the extreme opposite, native-like and unfolded states, respectively, implying essential stabilization of compact domains by enhancement of interfacial water networks and destabilization of a flexible active site by direct binding of DMSO to the unoccupied specific positions intended for elongated polypeptide substrates.
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Affiliation(s)
- Tatyana Tretyakova
- Institute for Biophysics and Bionanosciences at the Department of Physics, I. Javakhishvili Tbilisi State University, I. Chavchavadze Ave. 3, 0128 Tbilisi, Georgia
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34
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Khoshtariya DE, Dolidze TD, Tretyakova T, Waldeck DH, van Eldik R. Electron transfer with azurin at Au–SAM junctions in contact with a protic ionic melt: impact of glassy dynamics. Phys Chem Chem Phys 2013; 15:16515-26. [DOI: 10.1039/c3cp51896e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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35
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Monari S, Battistuzzi G, Bortolotti CA, Yanagisawa S, Sato K, Li C, Salard I, Kostrz D, Borsari M, Ranieri A, Dennison C, Sola M. Understanding the Mechanism of Short-Range Electron Transfer Using an Immobilized Cupredoxin. J Am Chem Soc 2012; 134:11848-51. [DOI: 10.1021/ja303425b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stefano Monari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Gianantonio Battistuzzi
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Carlo A. Bortolotti
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
- CNR-NANO Institute of Nanoscience, Via Campi 213/A, I-41125 Modena, Italy
| | - Sachiko Yanagisawa
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Katsuko Sato
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Chan Li
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Isabelle Salard
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Dorota Kostrz
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Marco Borsari
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Antonio Ranieri
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
| | - Christopher Dennison
- Institute for Cell and Molecular
Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, U.K
| | - Marco Sola
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183,
41125 Modena, Italy
- CNR-NANO Institute of Nanoscience, Via Campi 213/A, I-41125 Modena, Italy
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36
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Luska KL, Moores A. Rational size control of gold nanoparticles employing an organometallic precursor [Au-C≡C- t-Bu]4 and tunable thiolate-functionalized ionic liquids in organic medium. CAN J CHEM 2012. [DOI: 10.1139/v11-146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gold nanoparticles (Au NPs) stabilized with six different thiolate-functionalized ionic liquids (TFILs) were synthesized in an organic solvent. The size and optical properties of the TFIL-stabilized Au NPs can be rationally controlled by altering the N-alkyl chain length and (or) the counteranion of the TFIL-stabilizing ligand. Au NPs were prepared from the reduction of a gold precursor (HAuCl4 or [Au-C≡C-t-Bu]4) employing NaBH4 in the presence of the different disulfide precursors. A model, based on Israelachvili theory, is proposed to account for the dependence of NP size on the N-alkyl chain length and the counteranion of the surfactantlike TFIL stabilizers.
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Affiliation(s)
- Kylie L. Luska
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC H3A 2K6, Canada
| | - Audrey Moores
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC H3A 2K6, Canada
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Khoa Ly H, Wisitruangsakul N, Sezer M, Feng JJ, Kranich A, Weidinger IM, Zebger I, Murgida DH, Hildebrandt P. Electric-field effects on the interfacial electron transfer and protein dynamics of cytochrome c. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2010.12.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Electron transfer kinetics of cytochrome c immobilized on a phenolic terminated thiol self assembled monolayer determined by scanning electrochemical microscopy. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.03.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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Shushanyan M, Khoshtariya DE, Tretyakova T, Makharadze M, van Eldik R. Diverse role of conformational dynamics in carboxypeptidase A-driven peptide and ester hydrolyses: Disclosing the “Perfect Induced Fit” and “Protein Local Unfolding” pathways by altering protein stability. Biopolymers 2011; 95:852-70. [DOI: 10.1002/bip.21688] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 06/05/2011] [Indexed: 11/11/2022]
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41
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Ly HK, Sezer M, Wisitruangsakul N, Feng JJ, Kranich A, Millo D, Weidinger IM, Zebger I, Murgida DH, Hildebrandt P. Surface-enhanced vibrational spectroscopy for probing transient interactions of proteins with biomimetic interfaces: electric field effects on structure, dynamics and function of cytochrome c. FEBS J 2011; 278:1382-90. [PMID: 21352495 DOI: 10.1111/j.1742-4658.2011.08064.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Most of the biochemical and biophysical processes of proteins take place at membranes, and are thus under the influence of strong local electric fields, which are likely to affect the structure as well as the reaction mechanism and dynamics. To analyse such electric field effects, biomimetic interfaces may be employed that consist of membrane models deposited on nanostructured metal electrodes. For such devices, surface-enhanced resonance Raman and IR absorption spectroscopy are powerful techniques to disentangle the complex interfacial processes of proteins in terms of rotational diffusion, electron transfer, and protein and cofactor structural changes. The present article reviews the results obtained for the haem protein cytochrome c, which is widely used as a model protein for studying the various reaction steps of interfacial redox processes in general. In addition, it is shown that electric field effects may be functional for the natural redox processes of cytochrome c in the respiratory chain, as well as for the switch from the redox to the peroxidase function, one of the key events preceding apoptosis.
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Affiliation(s)
- Hong Khoa Ly
- Technische Universität Berlin, Institut für Chemie, Berlin, Germany
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42
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Waldeck DH, Khoshtariya DE. Fundamental Studies of Long- and Short-Range Electron Exchange Mechanisms between Electrodes and Proteins. MODERN ASPECTS OF ELECTROCHEMISTRY 2011. [DOI: 10.1007/978-1-4614-0347-0_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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43
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Muglali MI, Bashir A, Terfort A, Rohwerder M. Electrochemical investigations on stability and protonation behavior of pyridine-terminated aromatic self-assembled monolayers. Phys Chem Chem Phys 2011; 13:15530-8. [DOI: 10.1039/c1cp21469a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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44
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Gray HB, Winkler JR. Electron flow through metalloproteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1563-72. [PMID: 20460102 DOI: 10.1016/j.bbabio.2010.05.001] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 04/21/2010] [Accepted: 05/03/2010] [Indexed: 01/23/2023]
Abstract
Electron transfers in photosynthesis and respiration commonly occur between metal-containing cofactors that are separated by large molecular distances. Understanding the underlying physics and chemistry of these biological electron transfer processes is the goal of much of the work in our laboratories. Employing laser flash-quench triggering methods, we have shown that 20A, coupling-limited Fe(II) to Ru(III) and Cu(I) to Ru(III) electron tunneling in Ru-modified cytochromes and blue copper proteins can occur on the microsecond timescale both in solutions and crystals; and, further, that analysis of these rates suggests that distant donor-acceptor electronic couplings are mediated by a combination of sigma and hydrogen bonds in folded polypeptide structures. Redox equivalents can be transferred even longer distances by multistep tunneling, often called hopping, through intervening amino acid side chains. In recent work, we have found that 20A hole hopping through an intervening tryptophan is several hundred-fold faster than single-step electron tunneling in a Re-modified blue copper protein.
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Affiliation(s)
- Harry B Gray
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
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45
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Ly HK, Marti MA, Martin DF, Alvarez-Paggi D, Meister W, Kranich A, Weidinger IM, Hildebrandt P, Murgida DH. Thermal Fluctuations Determine the Electron-Transfer Rates of Cytochrome c in Electrostatic and Covalent Complexes. Chemphyschem 2010; 11:1225-35. [DOI: 10.1002/cphc.200900966] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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46
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47
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Georg S, Kabuss J, Weidinger IM, Murgida DH, Hildebrandt P, Knorr A, Richter M. Distance-dependent electron transfer rate of immobilized redox proteins: a statistical physics approach. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:046101. [PMID: 20481780 DOI: 10.1103/physreve.81.046101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 02/18/2010] [Indexed: 05/29/2023]
Abstract
The electron transfer kinetics of redox proteins adsorbed on metal electrodes coated with self-assembled monolayers (SAMs) of mercaptanes shows an unusual distance-dependence. For thick SAMs, the experimentally measured electron transfer rate constant k{exp} obeys the behavior predicted by Marcus theory [R. A. Marcus and N. Sutin, Biochim. Biophys. Acta 811, 265 (1985)], whereas for thin SAMs, k{exp} remains virtually constant [Z. Q. Feng, J. Chem. Soc., Faraday Trans. 93, 1367 (1997)]. In this work, we present a simple theoretical model system for the redox protein cytochrome c electrostatically bound to a SAM-coated electrode. A statistical average of the electron tunneling rate is calculated by accounting for all possible orientations of the model protein. This approach, which takes into account the electric field dependent orientational distribution, allows for a satisfactory description of the "saturation" regime in the high electric field limit. It further predicts a nonexponential behavior of the average electron transfer processes that may be experimentally checked by extending kinetic experiments to shorter sampling times, i.e., 1/k{exp}. For a comprehensive description of the overall kinetics in the saturation regime at sampling times of the order of <<1/k{exp}, it is essential to consider the dynamics of protein reorientation, which is not implemented in the present model.
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Affiliation(s)
- Sören Georg
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
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48
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Khoshtariya DE, Dolidze TD, Shushanyan M, Davis KL, Waldeck DH, van Eldik R. Fundamental signatures of short- and long-range electron transfer for the blue copper protein azurin at Au/SAM junctions. Proc Natl Acad Sci U S A 2010; 107:2757-62. [PMID: 20133645 PMCID: PMC2840312 DOI: 10.1073/pnas.0910837107] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The blue copper protein from Pseudomonas aeruginosa, azurin, immobilized at gold electrodes through hydrophobic interaction with alkanethiol self-assembled monolayers (SAMs) of the general type [-S-(CH(2))(n)-CH(3)] (n = 4, 10, and 15) was employed to gain detailed insight into the physical mechanisms of short- and long-range biomolecular electron transfer (ET). Fast scan cyclic voltammetry and a Marcus equation analysis were used to determine unimolecular standard rate constants and reorganization free energies for variable n, temperature (2-55 degrees C), and pressure (5-150 MPa) conditions. A novel global fitting procedure was found to account for the reduced ET rate constant over almost five orders of magnitude (covering different n, temperature, and pressure) and revealed that electron exchange is a direct ET process and not conformationally gated. All the ET data, addressing SAMs with thickness variable over ca. 12 A, could be described by using a single reorganization energy (0.3 eV), however, the values for the enthalpies and volumes of activation were found to vary with n. These data and their comparison with theory show how to discriminate between the fundamental signatures of short- and long-range biomolecular ET that are theoretically anticipated for the adiabatic and nonadiabatic ET mechanisms, respectively.
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Affiliation(s)
- Dimitri E. Khoshtariya
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
- Institute for Biophysics and Bio-Nanosciences, Department of Physics, Tbilisi State University, 0128 Tbilisi, Georgian Republic
- Department of Molecular Biophysics, Institute of Molecular Biology and Biophysics, 0160 Tbilisi, Georgian Republic; and
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260
| | - Tina D. Dolidze
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
- Institute for Biophysics and Bio-Nanosciences, Department of Physics, Tbilisi State University, 0128 Tbilisi, Georgian Republic
- Department of Molecular Biophysics, Institute of Molecular Biology and Biophysics, 0160 Tbilisi, Georgian Republic; and
| | - Mikhael Shushanyan
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
- Institute for Biophysics and Bio-Nanosciences, Department of Physics, Tbilisi State University, 0128 Tbilisi, Georgian Republic
| | - Kathryn L. Davis
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260
| | - David H. Waldeck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260
| | - Rudi van Eldik
- Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
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Abstract
Central to theories of electron transfer (ET) is the idea that nuclear motion generates a transition state that enables electron flow to proceed, but nuclear motion also induces fluctuations in the donor-acceptor (DA) electronic coupling that is the rate-limiting parameter for nonadiabatic ET. The interplay between the DA energy gap and DA coupling fluctuations is particularly noteworthy in biological ET, where flexible protein and mobile water bridges take center stage. Here, we discuss the critical timescales at play for ET reactions in fluctuating media, highlighting issues of the Condon approximation, average medium versus fluctuation-controlled electron tunneling, gated and solvent relaxation controlled electron transfer, and the influence of inelastic tunneling on electronic coupling pathway interferences. Taken together, one may use this framework to establish principles to describe how macromolecular structure and structural fluctuations influence ET reactions. This framework deepens our understanding of ET chemistry in fluctuating media. Moreover, it provides a unifying perspective for biophysical charge-transfer processes and helps to frame new questions associated with energy harvesting and transduction in fluctuating media.
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Affiliation(s)
| | - David H. Waldeck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260;
| | - David N. Beratan
- Departments of Chemistry and Biochemistry, Duke University, Durham, North Carolina 27708;
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50
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Khoshtariya DE, Dolidze TD, van Eldik R. Unusual mechanism for the short-range electron transfer within gold-alkanethiol-ionic-liquid films of subnanometer thickness. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:065101. [PMID: 20365213 DOI: 10.1103/physreve.80.065101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 11/06/2009] [Indexed: 05/29/2023]
Abstract
Exploiting nanoscopically tunable composite gold-alkanethiol-ionic-liquid/ferrocene self-assembled systems with tunable electron transfer distance, we discovered in the case of thinner alkanethiol films a thermally activated electron transfer pattern totally controlled by the viscosity-related slow relaxation mode(s) of the ionic liquid acting as the reactant's fluctuating environment. This pattern manifested through the activation enthalpy and volume parameters that are identical to those for viscous flow was explained in terms of the extreme adiabatic mechanism with a vanishing Marcus barrier (via the exponential Franck-Condon-like term approaching unity).
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Affiliation(s)
- Dimitri E Khoshtariya
- Department of Physics and Institute for Biophysics and Bionanosciences, I. Javakhishvili Tbilisi State University, I. Chavchavadze Avenue 3, Tbilisi, Georgia.
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