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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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Abstract
The immobilization of redox proteins or enzymes onto conductive surfaces has application in the analysis of biological processes, the fabrication of biosensors, and in the development of green technologies and biochemical synthetic approaches. This review evaluates the methods through which redox proteins can be attached to electrode surfaces in a "wired" configuration, that is, one that facilitates direct electron transfer. The feasibility of simple electroactive adsorption onto a range of electrode surfaces is illustrated, with a highlight on the recent advances that have been achieved in biotechnological device construction using carbon materials and metal oxides. The covalent crosslinking strategies commonly used for the modification and biofunctionalization of electrode surfaces are also evaluated. Recent innovations in harnessing chemical biology methods for electrically wiring redox biology to surfaces are emphasized.
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An energy decomposition analysis for intramolecular non-covalent interaction in solvated environment. Sci China Chem 2016. [DOI: 10.1007/s11426-016-0007-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Probing copper/tau protein interactions electrochemically. Anal Biochem 2013; 442:130-7. [DOI: 10.1016/j.ab.2013.07.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 07/05/2013] [Accepted: 07/09/2013] [Indexed: 01/08/2023]
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Residues PsaB Asp612 and PsaB Glu613 of photosystem I confer pH-dependent binding of plastocyanin and cytochrome c(6). Biochemistry 2012; 51:7297-303. [PMID: 22920401 DOI: 10.1021/bi300898j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The binding and electron transfer between plastocyanin (pc) or cytochrome c(6) (cyt c(6)) and photosystem I (PSI) can be described by hydrophobic as well as electrostatic interactions. The two α helices, l and l' in PsaB and PsaA, respectively, are involved in forming the hydrophobic interaction site at the oxidizing site of PSI. To obtain mechanistic insights into the function of the two negatively charged residues D612 and E613, present in α helix l of PsaB, we exchanged both residues by site-directed mutagenesis with His and transformed a PsaB deficient mutant of Chlamydomonas reinhardtii. Flash-induced absorption spectroscopy revealed that PSI harboring the changes D612H and E613H had a high affinity toward binding of the electron donors and possessed an altered pH dependence of electron transfer with pc and cyt c(6). Despite optimized binding and electron transfer between the altered PSI and its electron donors, the mutant strain PsaB-D612H/E613H exhibited a strong light sensitive growth phenotype, indicating that decelerated turnover between pc/cyt c(6) and PSI with respect to electron transfer is deleterious to the cells.
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The Importance of the Long Type 1 Copper‐Binding Loop of Nitrite Reductase for Structure and Function. Chemistry 2008; 14:5820-8. [DOI: 10.1002/chem.200701997] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Direct electron-transfer of native hemoglobin in blood: Kinetics and catalysis. Bioelectrochemistry 2008; 72:135-40. [DOI: 10.1016/j.bioelechem.2008.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 12/14/2007] [Accepted: 01/02/2008] [Indexed: 11/20/2022]
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Abstract
Many approaches are being used to engineer metalloproteins, with most of these informed by, and aiming to further elucidate, the basic structural requirements for biological metal centers. Cupredoxins are type 1 (T1) copper-containing electron transfer (ET) proteins with a -barrel fold that is thought to constrain metal site structure. The T1 copper ion is bound by ligands mainly originating from a single active site loop whose length and structure varies. This Highlight article will focus on protein engineering studies which have investigated the role of the metal-binding loop for active site integrity and functionality. Scaffold differences are present within the cupredoxin family and their influence has also been assessed. Given the widespread occurrence of -barrel domains in nature, and the array of metal sites in proteins composed of loop regions, the studies described on this model system have implications for a variety of metalloproteins.
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Thermodynamics of the alkaline transition in phytocyanins. J Biol Inorg Chem 2007; 12:895-900. [PMID: 17569996 DOI: 10.1007/s00775-007-0245-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2007] [Accepted: 04/29/2007] [Indexed: 10/23/2022]
Abstract
The thermodynamics of the alkaline transition which influences the spectral and redox properties of the type 1 copper center in phytocyanins has been determined spectroscopically. The proteins investigated include Rhus vernicifera stellacyanin, cucumber basic protein and its Met89Gln variant, and umecyanin, the stellacyanin from horseradish roots, along with its Gln95Met variant. The changes in reaction enthalpy and entropy within the protein series show partial compensatory behavior. Thus, the reaction free energy change (hence the pK (a) value) is rather variable. This indicates that species-dependent differences in reaction thermodynamics, although containing an important contribution from changes in the hydrogen-bonding network of water molecules in the hydration sphere of the protein (which feature enthalpy-entropy compensation), are to a large extent protein-based. The data for axial ligand variants are consistent with the hypothesis of a copper-binding His as the deprotonating residue responsible for this transition.
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Basic requirements for a metal-binding site in a protein: the influence of loop shortening on the cupredoxin azurin. Proc Natl Acad Sci U S A 2006; 103:7258-63. [PMID: 16651527 PMCID: PMC1464330 DOI: 10.1073/pnas.0600774103] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Indexed: 11/18/2022] Open
Abstract
The main active-site loop of the copper-binding protein azurin (a cupredoxin) has been shortened from C(112)TFPGH(117)SALM(121) to C(112)TPH(115)PFM(118) (the native loop from the cupredoxin amicyanin) and also to C(112)TPH(115)PM(117). The Cu(II) site structure is almost unaffected by shortening, as is that of the Cu(I) center at alkaline pH in the variant with the C(112)TPH(115)PM(117) loop sequence. Subtle spectroscopic differences due to alterations in the spin density distribution at the Cu(II) site can be attributed mainly to changes in the hydrogen-bonding pattern. Electron transfer is almost unaffected by the introduction of the C(112)TPH(115)PFM(118) loop, but removal of the Phe residue has a sizable effect on reactivity, probably because of diminished homodimer formation. At mildly acidic pH values, the His-115 ligand protonates and dissociates from the cuprous ion, an effect that has a dramatic influence on the reactivity of cupredoxins. These studies demonstrate that the amicyanin loop adopts a conformation identical to that found in the native protein when introduced into azurin, that a shorter than naturally occurring C-terminal active-site loop can support a functional T1 copper site, that CTPHPM is the minimal loop length required for binding this ubiquitous electron transfer center, and that the length and sequence of a metal-binding loop regulates a range of structural and functional features of the active site of a metalloprotein.
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Direct electrochemistry and electrocatalysis of heme-proteins in regenerated silk fibroin film. Anal Chim Acta 2006. [DOI: 10.1016/j.aca.2005.11.031] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Type 1 (T1) copper sites promote biological electron transfer and are found in the cupredoxins and a number of copper-containing enzymes including the multi-copper oxidases. A T1 copper site usually has a distorted tetrahedral geometry with strong ligands provided by the thiolate sulfur of a Cys and the imidazole nitrogens of two His residues. The active site structure is typically completed by a weak axial Met ligand (a second weak axial interaction is found in azurin resulting in a trigonal bipyramidal geometry). The axial Met is not conserved and Gln, Phe, Leu and Val are also found in this position. Three of the four ligands at a T1 copper site are situated on a single C-terminal loop whose length and structure varies. Studies are discussed which investigate both the influence of physiologically relevant axial ligand alterations, and also of mutations to the length and structure of the ligand-containing loop, on the properties of T1 copper sites.
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The influence of promoter and of electrode material on the cyclic voltammetry of Pisum sativum plastocyanin. Bioelectrochemistry 2002; 58:137-47. [PMID: 12414319 DOI: 10.1016/s1567-5394(02)00125-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The reversible cyclic voltammetry of pea plastocyanin (Pisum sativum) was studied with a wide range of electrodes: edge-oriented pyrolytic graphite (PGE), glassy carbon (GCE), gold (Au) and platinum (Pt) electrodes. Plastocyanin was coated onto the electrode surface by exploiting the electrostatic interaction between the negatively charged protein and a wide range of positively charged promoters. The effect of the redox response with an extended range of promoters, including poly-L-lysine, polymyxin B, neomycin, tobramycin, geneticin, spermine and spermidine, were included in this study. The resulting cyclic voltammograms reveal that the observed midpoint potential for plastocyanin can be shifted significantly depending on the choice of promoter. The stability of the negatively charged plastocyanin-promoter layer on an electrode was gauged by the rate of bulk diffusion of the protein from the immobilised film into the solution. Reversible cyclic voltammograms were obtained using edge-oriented pyrolytic graphite (PGE) and glassy carbon electrodes (GCE) with all promoters; however, platinum and gold electrodes were unable to sustain a defined redox response. The combination of pyrolytic graphite electrode/poly-L-lysine/plastocyanin was found to be the most stable combination, with a redox response which remained well defined in solution for more than 1 h at pH 7.0. The midpoint potentials obtained in this manner differed between the two graphite electrodes PGE and GCE using poly-L-lysine as the promoter. This effect was in addition to the expected pH dependence of the midpoint potential for plastocyanin and the results indicated that the pK(a) for plastocyanin on PGE was 4.94 compared to that on GCE of 4.66. It is concluded that both the electrode material and the nature of the promoter can influence the position of the redox potentials for proteins measured in vitro. This study extends the range of biogenic promoters used in combination with electrode materials. Thus, we can begin to develop a more comprehensive understanding of electrode-protein interactions and draw conclusions as to metalloprotein function, in vivo. To support these studies, we have sought information as to the nature of the electrode/promoter/protein interaction using scanning tunneling microscopy (STM) to study both the promoter and the plastocyanin protein on a gold surface.
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UV resonance Raman and NMR spectroscopic studies on the pH dependent metal ion release from pseudoazurin. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00937-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chlamydomonas genetics, a tool for the study of bioenergetic pathways. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1367:1-62. [PMID: 9784589 DOI: 10.1016/s0005-2728(98)00136-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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26
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Effect of surface activation on charge and mass transfer rates of the hexacyanoferrate(III)/(II) redox probe at fibrinogen-modified carbon paste electrodes. Anal Chim Acta 1997. [DOI: 10.1016/s0003-2670(96)00514-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Voltammetry of Plastocyanin at a Graphite Electrode: Effects of Structure, Charge, and Electrolyte. Inorg Chem 1996; 35:7156-7165. [PMID: 11666900 DOI: 10.1021/ic960620u] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Comparative voltammetric studies on Anabaena variabilis plastocyanin (positively charged at neutral pH) and spinach and poplar plastocyanins (negatively charged at neutral pH) have been undertaken at an edge-plane graphite electrode as a function of ionic strength, pH, and Mg(2+) concentration at 3 degrees C. The aim was to provide a more detailed understanding of the influence of the electrode-protein (solution) interfacial characteristics, as well as the variation of the formal potential with both the nature of the plastocyanin species and the pH. As might be expected, some of the interfacial properties associated with the positive charge on A. variabilis plastocyanin are the opposite of those observed with the negatively charged plastocyanins. For example, the linear diffusion component of the mass transport process for A. variabilis plastocyanin under the conditions of cyclic voltammetry is decreased and the radial diffusion component is increased by the addition of Mg(2+), whereas the reverse occurs with poplar and spinach plastocyanins. The voltammetrically determined reversible potentials for A. variabilis plastocyanin are considerably less positive than those for spinach and poplar plastocyanins, in agreement with values calculated from chemically based redox studies. Ionic strength effects, as determined by addition of NaClO(4) over the concentration range 0.005-0.20 M, are negligible for all three proteins. The addition of Mg(2+) causes a significant shift in the reversible potential toward more positive values for spinach and poplar plastocyanin but only a small positive shift for A. variabilis plastocyanin. The difference is attributed to a specific binding effect. The addition of Mg(2+) also dramatically alters the pH dependence of the reversible potential, indicating that the equilibrium between the protonated and unprotonated forms of reduced plastocyanin is modified by binding of Mg(2+) to the protein. It is concluded that the effects of biologically relevant redox-inactive cations such as Mg(2+) or Ca(2+) have to be considered carefully in studies of the redox chemistry of metalloproteins.
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The role of acidic residues of plastocyanin in its interaction with cytochrome ƒ. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1996. [DOI: 10.1016/s0005-2728(96)00090-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Reduction and Oxidation Processes of Blue Copper Proteins, Azurin, Pseudoazurin, Umecyanin, Stellacyanin, Plantacyanin, and Plastocyanin Approached by Cyclic and Potential Step Voltammetries. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1996. [DOI: 10.1246/bcsj.69.2855] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Transition metal complexes with sulfur ligands Part CXIV1. Alkylation, substitution reactions, electrochemistry and structure of nitrosyl and carbonyl complexes with the [Mo(‘S4’)] fragment (‘S4’2− = 1,2-bis(2-mercaptophenylthio) ethane (2−))2. Inorganica Chim Acta 1996. [DOI: 10.1016/0020-1693(95)04787-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Direct Electrochemistry of Blue Copper Proteins at Au Electrodes Modified with Promoters. CHEM LETT 1995. [DOI: 10.1246/cl.1995.1075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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32
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Abstract
In a survey, the analytical tools to characterise and optimise properties and stabilities of interfaces in thin film biosensors are discussed. After an introduction to microscopic and spectroscopic techniques and different transducers, case studies are presented. They concern bioaffinity sensors with particular emphasis on biomimetic recognition structures, catalytic sensors, transmembrane sensors, cell sensors, and the ambitious goal of addressing individual biomolecular function units.
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Chemical and electrochemical approaches to the investigation of redox reactions of simple electron transfer metalloproteins. Inorganica Chim Acta 1994. [DOI: 10.1016/0020-1693(94)04082-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Electrochemical reaction of cytochrome c at gold electrodes modified with thiophene containing one functional group. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0302-4598(94)80030-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Electron-transfer from cytochrome c to ascorbate oxidase and its type 2 copper-depleted derivatives. J Inorg Biochem 1994; 55:193-202. [PMID: 8057089 DOI: 10.1016/0162-0134(94)85020-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Rate constants have been determined for the electron-transfer reactions between reduced horse heart cytochrome c and resting cucumber ascorbate oxidase as functions of pH, ionic strength, and temperature. The second-order rate constant for the oxidation of reduced cytochrome c was determined to be k = 820 M-1 s-1 in 0.2 M phosphate buffer at pH 6.0 and 25 degrees C. The activation parameters were estimated to be delta H++ = 5 kJ mol-1 and delta S++ = -188 Jmol-1 K-1. The rate constants increased with decreasing buffer concentration, indicating that the electron-transfer from cytochrome c to ascorbate oxidase is realized by the local electrostatic interaction between them in spite of the reaction between positively charged proteins. Reactions of type 2 copper-depleted ascorbate oxidase whose type 3 coppers were in the reduced or oxidized form indicated that the type 1 copper site accepts an electron from cytochrome c. The reaction rate was remarkably increased with decreasing pH for both the native enzyme and derivatives. Further, on addition of hexametaphosphate anion the rate of the electron-transfer decreased because the association of both proteins to realize the electron-transfer was inhibited due to a change in distribution of the local charge on the protein surface(s).
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Direct electrochemical reactions of cytochrome c at iodide-modified electrodes. J Electroanal Chem (Lausanne) 1994. [DOI: 10.1016/0022-0728(94)87084-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Electron transfer reaction of stellacyanin at a bare glassy carbon electrode. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:813-9. [PMID: 8112333 DOI: 10.1111/j.1432-1033.1994.tb18562.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Direct (unmediated) electrochemistry of Rhus vernicifera stellacyanin at a glassy carbon electrode has been briefly investigated in phosphate buffer. The voltammetry was practically independent of the buffer concentration, suggesting that the interaction between stellacyanin and the glassy carbon electrode is mainly realized through the hydrophobic interaction. The quasi-reversible process was found to be diffusion controlled at a sweep rate < 80 mVs-1. From stellacyanin concentration dependence, a transformation from linear diffusion to radial diffusion was observed. Two-step voltammetry was affected by translocations of the active site (rotation of the protein molecule on the electrode surface and diffusion). Activation energies for reduction and oxidation processes were determined to be 24 kJmol-1 and 54 kJmol-1, respectively, by the stationary method, and 15 kJmol-1 and 66 kJmol-1, respectively, by cyclic voltammetry. The considerable difference in the activation energies is supposedly due to the reduction and oxidation which are performed utilizing different electron-transfer pathways or because only one electron-transfer pathway (probably through His92) is significantly changed during the reorganization between the oxidized and reduced forms. The fact that the diffusion constant estimated from one-step voltammetry (Dox = 4.2 x 10(-9) cm2 s-1 for 484 microM stellacyanin) is much smaller than that determined from cyclic voltammetry (7.5 x 10(-7) cm2 s-1) derives from the fact that motions of the stellacyanin molecule (rotation leading to translocation of the active site and diffusion) are not fast enough to allow data from potential step voltammetry to be treated as the reversible process, but are fast enough to allow data from cyclic voltammetry to be treated as a diffusion-controlled process.
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Direct electrochemistry of parsley plastocyanin on pyrolytic graphite electrodes. J Electroanal Chem (Lausanne) 1994. [DOI: 10.1016/0022-0728(93)02909-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Voltammetric studies of the catalytic electron-transfer process between the Desulfovibrio gigas hydrogenase and small proteins isolated from the same genus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:981-9. [PMID: 8223656 DOI: 10.1111/j.1432-1033.1993.tb18329.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The kinetics of electron transfer between the Desulfovibrio gigas hydrogenase and several electron-transfer proteins from Desulfovibrio species were investigated by cyclic voltammetry, square-wave voltammetry and chronoamperometry. The cytochrome c3 from Desulfovibrio vulgaris (Hildenborough), Desulfovibrio desulfuricans (Norway 4), Desulfovibrio desulfuricans (American Type Culture Collection 27774) and D. gigas (NCIB 9332) were used as redox carriers. They differ in their redox potentials and isoelectric point. Depending on the pH, all the reduced forms of these cytochromes were effective in electron exchange with hydrogenase. Other small electron-transfer proteins such as ferredoxin I, ferredoxin II and rubredoxin from D. gigas were tentatively used as redox carriers. Only ferredoxin II was effective in mediating electron exchange between hydrogenase and the working electrode. The second-order rate constants k for the reaction between reduced proteins and hydrogenase were calculated based on the theory of the simplest electrocatalytic mechanism [Moreno, C., Costa, C., Moura, I., Le Gall, J., Liu, M. Y., Payne, W. J., van Dijk, C. & Moura, J. J. G. (1993) Eur. J. Biochem. 212, 79-86] and the results obtained by cyclic voltammetry were compared with those obtained by chronoamperometry. Values for k of 10(5)-10(6) M-1 s-1 (cytochrome c3 as electron carrier) and 10(4) M-1 s-1 (ferredoxin II as the electron carrier) were determined. The rate-constant values are discussed in terms of the existence of an electrostatic interaction between the electrode surface and the redox carrier and between the redox carrier and a positively charged part of the enzyme.
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A comparative laser-flash absorption spectroscopy study of Anabaena PCC 7119 plastocyanin and cytochrome c6 photooxidation by photosystem I particles. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 213:1133-8. [PMID: 8504808 DOI: 10.1111/j.1432-1033.1993.tb17863.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Laser-flash absorption spectroscopy has been used to investigate the kinetics of electron transfer from reduced cytochrome c6 and plastocyanin, isolated from Anabaena PCC 7119, to oxidized P700 in photosystem-I particles isolated from the same cyanobacterium and from spinach. For all metalloproteins and photosystems, the observed rate constant has a non-linear protein-concentration dependence, thus suggesting complex formation preceding electron transfer. Plastocyanin and cytochrome c6 have similar association constants for complex formation with spinach photosystem I, but the copper protein exhibits a higher intracomplex-electron-transfer rate constant (twofold). With Anabaena photosystem I, the two redox proteins are more effective with respect to both complex formation (5-10-fold) and electron transfer (1.5-4-fold) than with the spinach photosystem. In all cases, the observed rate constants for electron-transfer monotonically decrease with increasing NaCl or MgCl2 concentration. This is interpreted in terms of the involvement of attractive electrostatic interactions, which result in the initial collision complex having the most productive orientation for the electron transfer process, without a requirement for further reorientation. The magnitude of the response to MgCl2 suggests the occurrence of specific ion effects as well. In the absence of added salts, the reduction rate of oxidized P700 increases with pH from approximately 6 to 8, but decreases slightly at pH 8.5.
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Robert Boyle anniversary lecture. New aspects of the electrochemistry of redox active metalloproteins and enzymes based on a microscopic model of electron transfer at the electrode–solution interface. ACTA ACUST UNITED AC 1992. [DOI: 10.1039/ap9922900132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Direct electrochemistry of proteins. Investigations of yeast cytochrome c mutants and their complexes with cytochrome b5. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 202:543-9. [PMID: 1662133 DOI: 10.1111/j.1432-1033.1991.tb16406.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Direct electrochemistry of site-specific mutants of yeast iso-1-cytochrome c (cyt c) and their complexes with bovine cytochrome b5 (cyt b5) has been investigated at edge-plane pyrolytic graphite (EPG) and bis(4-pyridyl)-disulphide-modified gold electrodes. Structure/function relationships have been investigated with the particular aim of clarifying the factors controlling the interactions of proteins at electrode/electrolyte interfaces and the determinants for direct electrochemistry in ternary protein/protein/electrode adducts, e.g. cyt c/cyt b5/EPG. Investigations of the cyt c mutants alone revealed a variety of electrochemical responses: all the mutants show similar voltammetric reversibility at modified gold electrodes, whereas at EPG electrodes the reversibility follows the order: Asn52Ile-Cys102Thr greater than Cys102Thr greater than Asn52Ala-Cys102Thr. Mid-point potentials follow the order: Arg13Ile (+60 +/- 5 mV vs. standard calomel electrode) greater than Cys102Thr (+40 +/- 5 mV) greater than Lys27Gln (+30 +/- 5 mV) approximately Lys72Asp (+30 +/- 5 mV) greater than Asn52Ala-Cys102Thr (+15 +/- 5 mV) greater than Asn52Ile-Cys102Thr (-10 +/- 5 mV). The structural basis for these differences is briefly discussed. When these mutants are bound to cyt b5, the differences in electrochemical response are greatly enhanced in the ternary cyt c/cyt b5/EPG adducts. A minimal analysis of these differences supports a model of multiple overlapping binding and recognition domains on cyt c which may be finely tuned to allow ternary complex formation so that a single-site variation could modify or abolish direct electrochemistry in the ternary adduct.
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Direct electrical communication of cytochrome c and ytochrome b5 at basal plane graphite electrodes modified with lauric acid or laurylamine. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0022-0728(91)80050-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Electrochemistry of spinach plastocyanin immobilised electrostatically at a gold electrode modified by [Cr(NH3)5NCS]2+. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0022-0728(91)85377-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Electron transfer reactions of metalloproteins at peptide-modified gold electrodes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 190:171-5. [PMID: 2163832 DOI: 10.1111/j.1432-1033.1990.tb15561.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The electron transfer reactions of four small redox proteins, cytochrome c. ferredoxin, plastocyanin and azurin, have been investigated at novel peptide-modified gold electrodes. These proved to be effective and selective in facilitating electron transfer. Good, quasi-reversible electron transfer was achieved selectively at different peptide-protein configurations by changing the pH or the ionic strength of the solution. The use of peptides as promoters for protein electrochemistry opens up the possibility of designing very specific electrode surfaces for larger molecules like enzymes.
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Voltammetric studies on the electrochemical behaviour of membrane-entrapped hemes. BIOLOGY OF METALS 1990; 3:122-4. [PMID: 2096898 DOI: 10.1007/bf01179518] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The electrochemical behaviour of Fe(III)-protoporphyrin IX entrapped into a cellulose triacetate membrane has been investigated by cyclic voltammetry. The physical entrapment into a solid matrix does not modify the redox properties of the entrapped hemes, which also act as efficient promoters in the electrochemistry of cytochrome c. Such a system represents a promising example of a simple 'solid-state' promoter, and stimulates further investigations in order to obtain more complex systems that may be of significance for basic and applied bioelectrochemistry.
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Electrochemical properties of pyrolytic graphite electrodes modified through adsorbed proteins. Electrochim Acta 1990. [DOI: 10.1016/0013-4686(90)85056-s] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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50
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Electrical activity controlling system for a mediator-coexisting alcohol dehydrogenase-NAD conductive membrane. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0022-0728(90)85100-j] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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