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Di Rocco G, Battistuzzi G, Ranieri A, Bortolotti CA, Borsari M, Sola M. Thermodynamics and Kinetics of Electron Transfer of Electrode-Immobilized Small Laccase from Streptomyces coelicolor. Molecules 2022; 27:molecules27228079. [PMID: 36432180 PMCID: PMC9692349 DOI: 10.3390/molecules27228079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/14/2022] [Accepted: 11/18/2022] [Indexed: 11/22/2022] Open
Abstract
The thermodynamic and kinetic properties for heterogeneous electron transfer (ET) were measured for the electrode-immobilized small laccase (SLAC) from Streptomyces coelicolor subjected to different electrostatic and covalent protein-electrode linkages, using cyclic voltammetry. Once immobilized electrostatically onto a gold electrode using mixed carboxyl- and hydroxy-terminated alkane-thiolate SAMs or covalently exploiting the same SAM subjected to N-hydroxysuccinimide+1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (NHS-EDC) chemistry, the SLAC-electrode electron flow occurs through the T1 center. The E°' values (from +0.2 to +0.1 V vs. SHE at pH 7.0) are lower by more than 0.2 V compared to the protein either in solution or immobilized with different anchoring strategies using uncharged SAMs. For the present electrostatic and covalent binding, this effect can, respectively, be ascribed to the negative charge of the SAM surfaces and to deletion of the positive charge of Lys/Arg residues due to amide bond formation which both selectively stabilize the more positively charged oxidized SLAC. Observation of enthalpy/entropy compensation within the series indicates that the immobilized proteins experience different reduction-induced solvent reorganization effects. The E°' values for the covalently attached SLAC are sensitive to three acid base equilibria, with apparent pKa values of pKa1ox = 5.1, pKa1red = 7.5, pKa2ox = 8.4, pKa2red = 10.9, pKa2ox = 8.9, pKa2red = 11.3 possibly involving one residue close to the T1 center and two residues (Lys and/or Arg) along with moderate protein unfolding, respectively. Therefore, the E°' value of immobilized SLAC turns out to be particularly sensitive to the anchoring mode and medium conditions.
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Affiliation(s)
- Giulia Di Rocco
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
| | - Gianantonio Battistuzzi
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
| | - Antonio Ranieri
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
- Correspondence: (A.R.); (M.B.)
| | - Carlo Augusto Bortolotti
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
| | - Marco Borsari
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
- Correspondence: (A.R.); (M.B.)
| | - Marco Sola
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 103, 41125 Modena, Italy
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2
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Electrochemical Characterization of an Engineered Red Copper Protein Featuring an Unprecedented Entropic Control of the Reduction Potential. Bioelectrochemistry 2022; 146:108095. [DOI: 10.1016/j.bioelechem.2022.108095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/04/2022] [Accepted: 03/10/2022] [Indexed: 12/12/2022]
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3
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Di Rocco G, Battistuzzi G, Borsari M, Bortolotti CA, Ranieri A, Sola M. The enthalpic and entropic terms of the reduction potential of metalloproteins: Determinants and interplay. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214071] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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4
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Adsorbing surface strongly influences the pseudoperoxidase and nitrite reductase activity of electrode-bound yeast cytochrome c. The effect of hydrophobic immobilization. Bioelectrochemistry 2020; 136:107628. [PMID: 32795942 DOI: 10.1016/j.bioelechem.2020.107628] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 02/02/2023]
Abstract
The Met80Ala and Met80Ala/Tyr67Ala variants of S. cerevisiae iso-1 cytochrome c (ycc) and their adducts with cardiolipin immobilized onto a gold electrode coated with a hydrophobic self-assembled monolayer (SAM) of decane-1-thiol were studied through cyclic voltammetry and surface-enhanced resonance Raman spectroscopy (SERRS). The electroactive species - containing a six-coordinate His/His axially ligated heme and a five-coordinate His/- heme stable in the oxidized and reduced state, respectively - and the pseudoperoxidase activity match those found previously for the wt species and are only slightly affected by CL binding. Most importantly, the reduced His/- ligated form of these variants is able to catalytically reduce the nitrite ion, while electrode-immobilized wt ycc and other His/Met heme ligated variants under a variety of conditions are not. Besides the pseudoperoxidase and nitrite reductase functions, which are the most physiologically relevant abilities of these constructs, also axial heme ligation and the equilibria between conformers are strongly affected by the nature - hydrophobic vs. electrostatic - of the non-covalent interactions determining protein immobilization. Also affected are the catalytic activity changes induced by a given mutation as well as those due to partial unfolding due to CL binding. It follows that under the same solution conditions the structural and functional properties of immobilized ycc are surface-specific and therefore cannot be transferred from an immobilized system to another involving different interfacial protein-SAM interactions.
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5
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Shin J, Gray HB, Winkler JR. Stability/activity tradeoffs in Thermusthermophilus HB27 laccase. J Biol Inorg Chem 2020; 25:233-238. [PMID: 31970489 DOI: 10.1007/s00775-020-01754-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/25/2019] [Indexed: 10/25/2022]
Abstract
We report the temperature dependence of the formal potential of type 1 copper (CuT1) in Thermusthermophilus HB27 laccase. Employing [Ru(NH3)4(bpy)](PF6)2 (0.505 vs. NHE) as the redox titrant, we found that the CuT12+/+ potential decreased from approximately 480 to 420 mV (vs. NHE) as the temperature was raised from 20 to 65 °C. Of importance is that the ΔSrc° of - 120 J mol-1 K-1 is substantially more negative than those for other blue copper proteins. We suggest that the highly unfavorable reduction entropy is attributable to CuT1 inaccessibility to the aqueous medium. Although the active site residues are buried, which is critical for maintaining thermostability, the flexibility around CuT1 is maintained, allowing enzyme activity at ambient temperature.
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Affiliation(s)
- Jieun Shin
- Beckman Institute, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Harry B Gray
- Beckman Institute, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Jay R Winkler
- Beckman Institute, California Institute of Technology, Pasadena, CA, 91125, USA.
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6
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Paradisi A, Lancellotti L, Borsari M, Bellei M, Bortolotti CA, Di Rocco G, Ranieri A, Sola M, Battistuzzi G. Met80 and Tyr67 affect the chemical unfolding of yeast cytochrome c: comparing the solution vs.immobilized state. RSC Chem Biol 2020. [DOI: 10.1039/d0cb00115e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The motional regime affects the unfolding propensity and axial heme coordination of the Met80Ala and Met80Ala/Tyr67Ala variants of yeast iso-1 cytochromec.
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Affiliation(s)
| | - Lidia Lancellotti
- Department of Chemistry and Geology
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
| | - Marco Borsari
- Department of Chemistry and Geology
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
| | - Marzia Bellei
- Department of Life Sciences
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
| | | | - Giulia Di Rocco
- Department of Life Sciences
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
| | - Antonio Ranieri
- Department of Life Sciences
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
| | - Marco Sola
- Department of Life Sciences
- University of Modena and Reggio Emilia
- 41126 Modena
- Italy
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7
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North ML, Wilcox DE. Shift from Entropic Cu 2+ Binding to Enthalpic Cu + Binding Determines the Reduction Thermodynamics of Blue Copper Proteins. J Am Chem Soc 2019; 141:14329-14339. [PMID: 31433629 DOI: 10.1021/jacs.9b06836] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enthalpic and entropic components of Cu2+ and Cu+ binding to the blue copper protein azurin have been quantified with isothermal titration calorimetry (ITC) measurements and analysis, providing the first such experimental values for Cu+ binding to a protein. The high affinity of azurin for Cu2+ is entirely due to a very favorable binding entropy, while its even higher affinity for Cu+ is due to a favorable binding enthalpy and entropy. The binding thermodynamics provide insight into bond enthalpies at the blue copper site and entropic contributions from desolvation and proton displacement. These values were used in thermodynamic cycles to determine the enthalpic and entropic contributions to the free energy of reduction and thus the reduction potential. The reduction thermodynamics obtained with this method are in good agreement with previous results from temperature-dependent electrochemical measurements. The calorimetry method, however, provides new insight into contributions from the initial (oxidized) and final (reduced) states of the reduction. Since ITC measurements quantify the protons that are displaced upon metal binding, the proton transfer that is coupled with electron transfer is also determined with this method. Preliminary results for Cu2+ and Cu+ binding to the Phe114Pro variant of azurin demonstrate the insight about protein tuning of the reduction potential that is provided by the binding thermodynamics of each metal oxidation state.
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Affiliation(s)
- Molly L North
- Department of Chemistry , Dartmouth College , Hanover , New Hampshire 03755 , United States
| | - Dean E Wilcox
- Department of Chemistry , Dartmouth College , Hanover , New Hampshire 03755 , United States
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8
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Mateljak I, Monza E, Lucas MF, Guallar V, Aleksejeva O, Ludwig R, Leech D, Shleev S, Alcalde M. Increasing Redox Potential, Redox Mediator Activity, and Stability in a Fungal Laccase by Computer-Guided Mutagenesis and Directed Evolution. ACS Catal 2019. [DOI: 10.1021/acscatal.9b00531] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Ivan Mateljak
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28094 Madrid, Spain
| | - Emanuele Monza
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- Zymvol, C/Almogavers 165, 08018 Barcelona, Spain
| | - Maria Fatima Lucas
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- Zymvol, C/Almogavers 165, 08018 Barcelona, Spain
| | - Victor Guallar
- Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona, Spain
- ICREA: Institució Catalana de Recerca i Estudis Avancats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Olga Aleksejeva
- Biomedical Sciences, Health and Society, Malmö University, 20560 Malmö, Sweden
| | - Roland Ludwig
- Department of Food Sciences and Technology, VIBT—Vienna Institute of Biotechnology, BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Donal Leech
- Department of Chemistry, National University of Ireland, Galway University Road, SW4 794 Galway, Ireland
| | - Sergey Shleev
- Biomedical Sciences, Health and Society, Malmö University, 20560 Malmö, Sweden
| | - Miguel Alcalde
- Department of Biocatalysis, Institute of Catalysis, CSIC, Cantoblanco, 28094 Madrid, Spain
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9
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Ma S, Ludwig R. Direct Electron Transfer of Enzymes Facilitated by Cytochromes. ChemElectroChem 2019; 6:958-975. [PMID: 31008015 PMCID: PMC6472588 DOI: 10.1002/celc.201801256] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/12/2018] [Indexed: 01/03/2023]
Abstract
The direct electron transfer (DET) of enzymes has been utilized to develop biosensors and enzymatic biofuel cells on micro- and nanostructured electrodes. Whereas some enzymes exhibit direct electron transfer between their active-site cofactor and an electrode, other oxidoreductases depend on acquired cytochrome domains or cytochrome subunits as built-in redox mediators. The physiological function of these cytochromes is to transfer electrons between the active-site cofactor and a redox partner protein. The exchange of the natural electron acceptor/donor by an electrode has been demonstrated for several cytochrome carrying oxidoreductases. These multi-cofactor enzymes have been applied in third generation biosensors to detect glucose, lactate, and other analytes. This review investigates and classifies oxidoreductases with a cytochrome domain, enzyme complexes with a cytochrome subunit, and covers designed cytochrome fusion enzymes. The structurally and electrochemically best characterized proponents from each enzyme class carrying a cytochrome, that is, flavoenzymes, quinoenzymes, molybdenum-cofactor enzymes, iron-sulfur cluster enzymes, and multi-haem enzymes, are featured, and their biochemical, kinetic, and electrochemical properties are compared. The cytochromes molecular and functional properties as well as their contribution to the interdomain electron transfer (IET, between active-site and cytochrome) and DET (between cytochrome and electrode) with regard to the achieved current density is discussed. Protein design strategies for cytochrome-fused enzymes are reviewed and the limiting factors as well as strategies to overcome them are outlined.
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Affiliation(s)
- Su Ma
- Biocatalysis and Biosensing Laboratory Department of Food Science and TechnologyBOKU – University of Natural Resources and Life SciencesMuthgasse 181190ViennaAustria
| | - Roland Ludwig
- Biocatalysis and Biosensing Laboratory Department of Food Science and TechnologyBOKU – University of Natural Resources and Life SciencesMuthgasse 181190ViennaAustria
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10
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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11
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Olloqui-Sariego JL, Márquez I, Frutos-Beltrán E, Díaz-Moreno I, De la Rosa MA, Calvente JJ, Andreu R, Díaz-Quintana A. Key Role of the Local Hydrophobicity in the East Patch of Plastocyanins on Their Thermal Stability and Redox Properties. ACS OMEGA 2018; 3:11447-11454. [PMID: 31459248 PMCID: PMC6645426 DOI: 10.1021/acsomega.8b01612] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/06/2018] [Indexed: 06/10/2023]
Abstract
Understanding the molecular basis of the thermal stability and functionality of redox proteins has important practical applications. Here, we show a distinct thermal dependence of the spectroscopic and electrochemical properties of two plastocyanins from the thermophilic cyanobacterium Phormidium laminosum and their mesophilic counterpart from Synechocystis sp. PCC 6803, despite the similarity of their molecular structures. To explore the origin of these differences, we have mimicked the local hydrophobicity in the east patch of the thermophilic protein by replacing a valine of the mesophilic plastocyanin by isoleucine. Interestingly, the resulting mutant approaches the thermal stability, redox thermodynamics, and dynamic coupling of the flexible site motions of the thermophilic protein, indicating the existence of a close connection between the hydrophobic packing of the east patch region of plastocyanin and the functional control and stability of the oxidized and reduced forms of the protein.
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Affiliation(s)
- José Luis Olloqui-Sariego
- Departamento
de Química Física, Universidad
de Sevilla, c/ Profesor García González, 1, 41012 Sevilla, Spain
| | - Inmaculada Márquez
- Departamento
de Química Física, Universidad
de Sevilla, c/ Profesor García González, 1, 41012 Sevilla, Spain
| | - Estrella Frutos-Beltrán
- Instituto
de Investigaciones Químicas, cicCartuja, Universidad de Sevilla y CSIC, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Irene Díaz-Moreno
- Instituto
de Investigaciones Químicas, cicCartuja, Universidad de Sevilla y CSIC, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Miguel A. De la Rosa
- Instituto
de Investigaciones Químicas, cicCartuja, Universidad de Sevilla y CSIC, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
| | - Juan José Calvente
- Departamento
de Química Física, Universidad
de Sevilla, c/ Profesor García González, 1, 41012 Sevilla, Spain
| | - Rafael Andreu
- Departamento
de Química Física, Universidad
de Sevilla, c/ Profesor García González, 1, 41012 Sevilla, Spain
| | - Antonio Díaz-Quintana
- Instituto
de Investigaciones Químicas, cicCartuja, Universidad de Sevilla y CSIC, Avd. Américo Vespucio 49, 41092 Sevilla, Spain
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13
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Alvarez-Paggi D, Zitare UA, Szuster J, Morgada MN, Leguto AJ, Vila AJ, Murgida DH. Tuning of Enthalpic/Entropic Parameters of a Protein Redox Center through Manipulation of the Electronic Partition Function. J Am Chem Soc 2017; 139:9803-9806. [PMID: 28662578 DOI: 10.1021/jacs.7b05199] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Manipulation of the partition function (Q) of the redox center CuA from cytochrome c oxidase is attained by tuning the accessibility of a low lying alternative electronic ground state and by perturbation of the electrostatic potential through point mutations, loop engineering and pH variation. We report clear correlations of the entropic and enthalpic contributions to redox potentials with Q and with the identity and hydrophobicity of the weak axial ligand, respectively.
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Affiliation(s)
- Damian Alvarez-Paggi
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Ulises A Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Jonathan Szuster
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Alcides J Leguto
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
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14
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Maheshwaran D, Nagendraraj T, Manimaran P, Ashokkumar B, Kumar M, Mayilmurugan R. A Highly Selective and Efficient Copper(II) - “Turn-On” Fluorescence Imaging Probe forl-Cysteine. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201601229] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Duraiyarasu Maheshwaran
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; 625021 Madurai Tamil Nadu India
| | - Thavasilingam Nagendraraj
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; 625021 Madurai Tamil Nadu India
| | - Paramasivam Manimaran
- School of Biotechnology; Madurai Kamaraj University; 625021 Madurai Tamil Nadu India
| | | | - Mukesh Kumar
- Solid State Physics Division; Physics Group; Bhabha Atomic Research Center; Mumbai Maharashtra India
| | - Ramasamy Mayilmurugan
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; 625021 Madurai Tamil Nadu India
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15
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Maheshwaran D, Priyanga S, Mayilmurugan R. Copper(ii)-benzimidazole complexes as efficient fluorescent probes forl-cysteine in water. Dalton Trans 2017; 46:11408-11417. [DOI: 10.1039/c7dt01895a] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Copper(ii)-benzimidazole complexes could detectl-cysteine over other natural amino acids at pH 7.34 by a ‘turn-on’ fluorescence mechanismviathe reduction of Cu(ii) to Cu(i) followed by displacement with excellent selectivity.
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Affiliation(s)
- Duraiyarasu Maheshwaran
- Bioinorganic Chemistry Laboratory/Physical Chemistry
- School of Chemistry
- Madurai Kamaraj University
- Madurai 625 021
- India
| | - Selvarasu Priyanga
- Bioinorganic Chemistry Laboratory/Physical Chemistry
- School of Chemistry
- Madurai Kamaraj University
- Madurai 625 021
- India
| | - Ramasamy Mayilmurugan
- Bioinorganic Chemistry Laboratory/Physical Chemistry
- School of Chemistry
- Madurai Kamaraj University
- Madurai 625 021
- India
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16
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Hosseinzadeh P, Lu Y. Design and fine-tuning redox potentials of metalloproteins involved in electron transfer in bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:557-581. [PMID: 26301482 PMCID: PMC4761536 DOI: 10.1016/j.bbabio.2015.08.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 08/20/2015] [Indexed: 12/25/2022]
Abstract
Redox potentials are a major contributor in controlling the electron transfer (ET) rates and thus regulating the ET processes in the bioenergetics. To maximize the efficiency of the ET process, one needs to master the art of tuning the redox potential, especially in metalloproteins, as they represent major classes of ET proteins. In this review, we first describe the importance of tuning the redox potential of ET centers and its role in regulating the ET in bioenergetic processes including photosynthesis and respiration. The main focus of this review is to summarize recent work in designing the ET centers, namely cupredoxins, cytochromes, and iron-sulfur proteins, and examples in design of protein networks involved these ET centers. We then discuss the factors that affect redox potentials of these ET centers including metal ion, the ligands to metal center and interactions beyond the primary ligand, especially non-covalent secondary coordination sphere interactions. We provide examples of strategies to fine-tune the redox potential using both natural and unnatural amino acids and native and nonnative cofactors. Several case studies are used to illustrate recent successes in this area. Outlooks for future endeavors are also provided. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.
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Affiliation(s)
- Parisa Hosseinzadeh
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA
| | - Yi Lu
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA.
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17
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Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 559] [Impact Index Per Article: 55.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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18
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Manceau A, Simionovici A, Lanson M, Perrin J, Tucoulou R, Bohic S, Fakra SC, Marcus MA, Bedell JP, Nagy KL. Thlaspi arvense binds Cu(ii) as a bis-(l-histidinato) complex on root cell walls in an urban ecosystem. Metallomics 2013; 5:1674-84. [DOI: 10.1039/c3mt00215b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Ranieri A, Battistuzzi G, Borsari M, Bortolotti CA, Di Rocco G, Sola M. pH and solvent H/D isotope effects on the thermodynamics and kinetics of electron transfer for electrode-immobilized native and urea-unfolded stellacyanin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15087-15094. [PMID: 23009339 DOI: 10.1021/la303363h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The thermodynamics of Cu(II) to Cu(I) reduction and the kinetics of the electron transfer (ET) process for Rhus vernicifera stellacyanin (STC) immobilized on a decane-1-thiol coated gold electrode have been measured through cyclic voltammetry at varying pH and temperature, in the presence of urea and in D(2)O. Immobilized STC undergoes a limited conformational change that mainly results in an enhanced exposure of one or both copper binding histidines to solvent which slightly stabilizes the cupric state and increases histidine basicity. The large immobilization-induced increase in the pK(a) for the acid transition (from 4.5 to 6.3) makes this electrode-SAM-protein construct an attractive candidate as a biomolecular ET switch operating near neutral pH in molecular electronics. Such a potential interest is increased by the robustness of this interface against chemical unfolding as it undergoes only moderate changes in the reduction thermodynamics and in the ET rate in the presence of up to 8 M urea. The sensitivity of these parameters to solvent H/D isotope effects testifies to the role of protein solvation as effector of the thermodynamics and kinetics of ET.
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Affiliation(s)
- Antonio Ranieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Modena, Italy
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20
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Voltammetric study of the adsorbed thermophilic plastocyanin from Phormidium laminosum up to 90°C. Electrochem commun 2012. [DOI: 10.1016/j.elecom.2012.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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21
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Freed KF. Entropy−Enthalpy Compensation in Chemical Reactions and Adsorption: An Exactly Solvable Model. J Phys Chem B 2011; 115:1689-92. [DOI: 10.1021/jp1105696] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Karl F. Freed
- James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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22
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Shumyantseva VV, Bulko TV, Suprun EV, Chalenko YM, Yu.Vagin M, Rudakov YO, Shatskaya MA, Archakov AI. Electrochemical investigations of cytochrome P450. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:94-101. [DOI: 10.1016/j.bbapap.2010.07.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 06/22/2010] [Accepted: 07/04/2010] [Indexed: 10/19/2022]
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23
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Guo K, Hu Y, Zhang Y, Liu B, Magner E. Electrochemistry of nanozeolite-immobilized cytochrome c in aqueous and nonaqueous solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9076-9081. [PMID: 20373776 DOI: 10.1021/la904630c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The electrochemical properties of cytochrome c (cyt c) immobilized on multilayer nanozeolite-modified electrodes have been examined in aqueous and nonaqueous solutions. Layers of Linde type-L zeolites were assembled on indium tin oxide (ITO) glass electrodes followed by the adsorption of cyt c, primarily via electrostatic interactions, onto modified ITO electrodes. The heme protein displayed a quasi-reversible response in aqueous solution with a redox potential of +324 mV (vs NHE), and the surface coverage (Gamma*) increased linearly for the first four layers and then gave a nearly constant value of 200 pmol cm(-2). On immersion of the modified electrodes in 95% (v/v) nonaqueous solutions, the redox potential decreased significantly, a decrease that originated from changes in both the enthalpy and entropy of reduction. On reimmersion of the modified electrode in buffer, the faradic response immediately returned to its original value. These results demonstrate that nanozeolites are potential stable supports for redox proteins and enzymes.
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Affiliation(s)
- Kai Guo
- Department of Chemistry, Fudan University, Shanghai 200433, China
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24
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Rationally tuning the reduction potential of a single cupredoxin beyond the natural range. Nature 2009; 462:113-6. [PMID: 19890331 DOI: 10.1038/nature08551] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/30/2009] [Indexed: 11/08/2022]
Abstract
Redox processes are at the heart of numerous functions in chemistry and biology, from long-range electron transfer in photosynthesis and respiration to catalysis in industrial and fuel cell research. These functions are accomplished in nature by only a limited number of redox-active agents. A long-standing issue in these fields is how redox potentials are fine-tuned over a broad range with little change to the redox-active site or electron-transfer properties. Resolving this issue will not only advance our fundamental understanding of the roles of long-range, non-covalent interactions in redox processes, but also allow for design of redox-active proteins having tailor-made redox potentials for applications such as artificial photosynthetic centres or fuel cell catalysts for energy conversion. Here we show that two important secondary coordination sphere interactions, hydrophobicity and hydrogen-bonding, are capable of tuning the reduction potential of the cupredoxin azurin over a 700 mV range, surpassing the highest and lowest reduction potentials reported for any mononuclear cupredoxin, without perturbing the metal binding site beyond what is typical for the cupredoxin family of proteins. We also demonstrate that the effects of individual structural features are additive and that redox potential tuning of azurin is now predictable across the full range of cupredoxin potentials.
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25
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Tian Y, Ran Q, Xu J, Xian Y, Peng R, Jin L. High-Quality Covalently Grafting Hemoglobin on Gold Electrodes: Characterization, Redox Thermodynamics and Bio-electrocatalysis. Chemphyschem 2009; 10:3105-11. [DOI: 10.1002/cphc.200900588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Active site loop dictates the thermodynamics of reduction and ligand protonation in cupredoxins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:995-1000. [PMID: 19230853 DOI: 10.1016/j.bbapap.2009.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/28/2009] [Accepted: 02/03/2009] [Indexed: 11/21/2022]
Abstract
The thermodynamics of reduction and His ligand protonation have been determined for a range of loop-contraction variants of the electron transferring type 1 copper protein azurin (AZ). For AZPC, in which the native C-terminal loop containing the Cys, His and Met ligands has been replaced with the shorter sequence from plastocyanin (PC) and AZAMI, in which the even shorter amicyanin (AMI) loop has been inserted, the thermodynamics of reduction match those of the protein whose loop has been introduced which are different to the values for AZ. The enthalpic contribution to His ligand protonation, which is not observed in AZ, is similar in AZAMI and AMI. The thermodynamics of this process in AZPC are more dissimilar to those for PC. In the case of AZAMI-F, a variant possessing the (non natural) minimal loop that can bind a type 1 copper site, the reduction thermodynamics are intermediate between those of AZPC and AZAMI, whilst the thermodynamic data for His ligand protonation are very similar to those for AMI. The results for AZAMI and AZPC are primarily due to protein based enthalpic effects related to the interaction of the metal with permanent protein dipoles from the loop, and to the decreased loop length which favors His ligand protonation in the cuprous proteins. Entropic factors related to loop flexibility have little influence because of constraints imposed by metal coordination and the fact that the introduced loops pack well against the AZ scaffold. Thus, the host scaffold in general plays a minor thermodynamic role in both processes, although for AZAMI-F differences in the first and second coordination spheres influence the thermodynamics of reduction.
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27
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Ranieri A, Battistuzzi G, Borsari M, Casalini S, Fontanesi C, Monari S, Siwek MJ, Sola M. Thermodynamics and kinetics of the electron transfer process of spinach plastocyanin adsorbed on a modified gold electrode. J Electroanal Chem (Lausanne) 2009. [DOI: 10.1016/j.jelechem.2008.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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28
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Tomo T, Kato Y, Suzuki T, Akimoto S, Okubo T, Noguchi T, Hasegawa K, Tsuchiya T, Tanaka K, Fukuya M, Dohmae N, Watanabe T, Mimuro M. Characterization of highly purified photosystem I complexes from the chlorophyll d-dominated cyanobacterium Acaryochloris marina MBIC 11017. J Biol Chem 2008; 283:18198-209. [PMID: 18458090 DOI: 10.1074/jbc.m801805200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photochemically active photosystem (PS) I complexes were purified from the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina MBIC 11017, and several of their properties were characterized. PS I complexes consist of 11 subunits, including PsaK1 and PsaK2; a new small subunit was identified and named Psa27. The new subunit might replace the function of PsaI that is absent in A. marina. The amounts of pigments per one molecule of Chl d' were 97.0 +/- 11.0 Chl d, 1.9 +/- 0.5 Chl a, 25.2 +/- 2.4 alpha-carotene, and two phylloquinone molecules. The light-induced Fourier transform infrared difference spectroscopy and light-induced difference absorption spectra reconfirmed that the primary electron donor of PS I (P740) was the Chl d dimer. In addition to P740, the difference spectrum contained an additional band at 728 nm. The redox potentials of P740 were estimated to be 439 mV by spectroelectrochemistry; this value was comparable with the potential of P700 in other cyanobacteria and higher plants. This suggests that the overall energetics of the PS I reaction were adjusted to the electron acceptor side to utilize the lower light energy gained by P740. The distribution of charge in P740 was estimated by a density functional theory calculation, and a partial localization of charge was predicted to P1 Chl (special pair Chl on PsaA). Based on differences in the protein matrix and optical properties of P740, construction of the PS I core in A. marina was discussed.
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Affiliation(s)
- Tatsuya Tomo
- Department of Technology and Ecology, Hall of Global Environmental Research, Kyoto University, Kyoto, Japan.
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29
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LeBard DN, Matyushov DV. Redox entropy of plastocyanin: Developing a microscopic view of mesoscopic polar solvation. J Chem Phys 2008; 128:155106. [DOI: 10.1063/1.2904879] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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30
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Manceau A, Nagy KL, Marcus MA, Lanson M, Geoffroy N, Jacquet T, Kirpichtchikova T. Formation of metallic copper nanoparticles at the soil-root interface. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:1766-72. [PMID: 18441833 DOI: 10.1021/es072017o] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Copper is an essential element in the cellular electron-transport chain, but as a free ion it can catalyze production of damaging radicals. Thus, all life forms attempt to prevent copper toxicity. Plants diminish excess copper in two structural regions: rare hyperaccumulators bind cationic copper to organic ligands in subaerial tissues, whereas widespread metal-tolerant plants segregate copper dominantly in roots by mechanisms thought to be analogous. Here we show using synchrotron microanalyses that common wetlands plants Phragmites australis and Iris pseudoacorus can transform copper into metallic nanoparticles in and near roots with evidence of assistance by endomycorrhizal fungi when grown in contaminated soil in the natural environment. Biomolecular responses to oxidative stress, similar to reactions used to abiotically synthesize Cu0 nanostructures of controlled size and shape, likely cause the transformation. This newly identified mode of copper biomineralization by plant roots under copper stress may be common in oxygenated environments.
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Affiliation(s)
- Alain Manceau
- LGIT-Maison des Géosciences, CNRS and Université J. Fourier, 38041 Grenoble 9, France.
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31
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Andrés GO, Cabrerizo FM, Martínez-Junza V, Braslavsky SE. A Large Entropic Term Due to Water Rearrangement is Concomitant with the Photoproduction of Anionic Free-Base Porphyrin Triplet States in Aqueous Solutions†. Photochem Photobiol 2007; 83:503-10. [PMID: 17094719 DOI: 10.1562/2006-09-02-ra-1026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The enthalpy change, DeltaTH, and volume change, DeltaTV, associated with triplet state formation upon excitation of free-base meso-tetra-(4-sulfonatophenyl)porphyrin, TSPP4-, its Zn derivative, ZnTSPP4-, and meso-tetra-(4-carboxyphenyl)porphyrin, TCPP4-, were obtained in aqueous solutions by the application of laser-induced optoacoustics spectroscopy in the presence of phosphate salts of various monovalent cations (Li+, Na+, K+, NH4+ and Cs+). A linear correlation was found between DeltaTH and DeltaTV at different phosphate concentrations for the free-base porphyrins. The intercepts (132 +/- 8 kJ mol(-1) for TSPP4- and 164 +/- 23 kJ mol(-1) for TCPP4-) of these plots correspond to the respective value of the triplet energy content obtained from phosphorescence at 77 K (140 and 149 kJ mol(-1)). This suggests that DeltaTG for the triplet state formation is independent of the medium and an enthalpy-entropy compensation is responsible for the much smaller and salt-dependent DeltaTH values obtained at room temperature. The Gibbs energy for triplet state formation of the free-base porphyrins at room temperature is thus mainly determined by the entropic term due to solvent rearrangement. The DeltaTH values for 3ZnTSPP4- at different buffer concentrations and different cations are all between 130 and 150 kJ mol(-1), close to the triplet energy obtained from phosphorescence (E(T) = 155 kJ mol(-1)). The solvent structure and the nature of the counterion have a negligible influence on the 3ZnTSPP4-formation due to the blockage of the electron pairs on the central N atoms. Thus, the small DeltaTV value should be due to intrinsic bond changes upon 3ZnTSPP4- formation and no correlation between DeltaTH and DeltaTV should be expected in this case. The enthalpy change determines the Gibbs energy for 3ZnTSPP4-formation at room temperature.
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Affiliation(s)
- Gabriel O Andrés
- Max-Planck-Institut für Bioanorganische Chemie (formerly Strahlenchemie), Mülheim an der Ruhr, Germany
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32
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Hulsker R, Mery A, Thomassen EA, Ranieri A, Sola M, Verbeet MP, Kohzuma T, Ubbink M. Protonation of a Histidine Copper Ligand in Fern Plastocyanin. J Am Chem Soc 2007; 129:4423-9. [PMID: 17367139 DOI: 10.1021/ja0690464] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plastocyanin is a small blue copper protein that shuttles electrons as part of the photosynthetic redox chain. Its redox behavior is changed at low pH as a result of protonation of the solvent-exposed copper-coordinating histidine. Protonation and subsequent redox inactivation could have a role in the down regulation of photosynthesis. As opposed to plastocyanin from other sources, in fern plastocyanin His90 protonation at low pH has been reported not to occur. Two possible reasons for that have been proposed: pi-pi stacking between Phe12 and His90 and lack of a hydrogen bond with the backbone oxygen of Gly36. We have produced this fern plastocyanin recombinantly and examined the properties of wild-type protein and mutants Phe12Leu, Gly36Pro, and the double mutant with NMR spectroscopy, X-ray crystallography, and cyclic voltammetry. The results demonstrate that, contrary to earlier reports, protonation of His90 in the wild-type protein does occur in solution with a pKa of 4.4 (+/-0.1). Neither the single mutants nor the double mutant exhibit a change in protonation behavior, indicating that the suggested interactions have no influence. The crystal structure at low pH of the Gly36Pro variant does not show His90 protonation, similar to what was found for the wild-type protein. The structure suggests that movement of the imidazole ring is hindered by crystal contacts. This study illustrates a significant difference between results obtained in solution by NMR and by crystallography.
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Affiliation(s)
- Rinske Hulsker
- Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
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33
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Santini JM, Kappler U, Ward SA, Honeychurch MJ, vanden Hoven RN, Bernhardt PV. The NT-26 cytochrome c552 and its role in arsenite oxidation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:189-96. [PMID: 17306216 DOI: 10.1016/j.bbabio.2007.01.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 01/09/2007] [Accepted: 01/16/2007] [Indexed: 10/23/2022]
Abstract
Arsenite oxidation by the facultative chemolithoautotroph NT-26 involves a periplasmic arsenite oxidase. This enzyme is the first component of an electron transport chain which leads to reduction of oxygen to water and the generation of ATP. Involved in this pathway is a periplasmic c-type cytochrome that can act as an electron acceptor to the arsenite oxidase. We identified the gene that encodes this protein downstream of the arsenite oxidase genes (aroBA). This protein, a cytochrome c(552), is similar to a number of c-type cytochromes from the alpha-Proteobacteria and mitochondria. It was therefore not surprising that horse heart cytochrome c could also serve, in vitro, as an alternative electron acceptor for the arsenite oxidase. Purification and characterisation of the c(552) revealed the presence of a single heme per protein and that the heme redox potential is similar to that of mitochondrial c-type cytochromes. Expression studies revealed that synthesis of the cytochrome c gene was not dependent on arsenite as was found to be the case for expression of aroBA.
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34
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Battistuzzi G, Bellei M, De Rienzo F, Sola M. Redox properties of the Fe3+/Fe2+ couple in Arthromyces ramosus class II peroxidase and its cyanide adduct. J Biol Inorg Chem 2006; 11:586-92. [PMID: 16791642 DOI: 10.1007/s00775-006-0108-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
The thermodynamics of the one-electron reduction of the ferric heme in free and cyanide-bound Arthromyces ramosus peroxidase (ARP), a class II plant peroxidase, were determined through spectro-electrochemical experiments. The data were compared with those for class III horseradish peroxidase C (HRP) and its cyanide adduct, and were interpreted in terms of ligand binding features, electrostatic effects and solvent accessible surface area of the heme group and of catalytically relevant residues in the heme distal site. The E(o)' values for free and cyanide-bound ARP (-0.183 and -0.390 V, respectively, at 25 degrees C and pH 7) are higher than those for HRP and HRP-CN. ARP features an enthalpic stabilization of the ferrous state and a remarkably negative reduction entropy, which are both unprecedented for heme peroxidases. Once the compensatory contributions of solvent reorganization are partitioned from the measured reduction enthalpy, the resulting protein-based deltaH(o)'(rc(int)) value for ARP turns out to be less positive than that for HRP by +10 kJ mol(-1). The smaller stabilization of the oxidized heme in ARP most probably results from the less pronounced anionic character of the proximal histidine, and the decreased polarity in the heme distal site as compared with HRP, as indicated by the X-ray structures. The surprisingly negative deltaS(o)'(rc) value for ARP is the result of peculiar reduction-induced solvent reorganization effects.
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Affiliation(s)
- Gianantonio Battistuzzi
- Department of Chemistry and Centro SCS, University of Modena and Reggio Emilia, Via Campi 183, 41100, Modena, Italy
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35
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He X, Zhu L. Direct electrochemistry of hemoglobin in cetylpyridinium bromide film: Redox thermodynamics and electrocatalysis to nitric oxide. Electrochem commun 2006. [DOI: 10.1016/j.elecom.2006.02.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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36
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Bortolotti CA, Battistuzzi G, Borsari M, Facci P, Ranieri A, Sola M. The Redox Chemistry of the Covalently Immobilized Native and Low-pH Forms of Yeast Iso-1-cytochromec. J Am Chem Soc 2006; 128:5444-51. [PMID: 16620116 DOI: 10.1021/ja0573662] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic voltammetry experiments were carried out on native Saccharomyces cerevisiae iso-1-cytochrome c and its C102T/N62C variant immobilized on bare polycrystalline gold electrode through the S-Au bond formed by a surface cysteine. Experiments were carried out at different temperatures (5-65 degrees C) and pH values (1.5-7). The E degrees ' value at pH 7 (+370 mV vs SHE) is approximately 100 mV higher than that for the protein in solution. This difference is enthalpic in origin and is proposed to be the result of the electrostatic repulsion among the densely packed molecules onto the electrode surface. Two additional electrochemical waves are observed upon lowering the pH below 5 (E degrees ' = +182 mV) and 3 (E degrees ' = +71 mV), which are attributed to two conformers (referred to as "intermediate" and "acidic", respectively) featuring an altered heme axial ligation. This is the first determination of the reduction potential for low-pH conformers of cytochrome c in the absence of denaturants. Since the native form of cytochrome c can be restored, bringing back the pH to neutrality, the possibility offered by this transition to reversibly modulate the redox potential of cytochrome c is appealing for bioelectronic applications. The immobilized C102T/N62C variant, which differs from the native protein in the orientation of the heme group with respect to the electrode, shows very similar reduction thermodynamics. For both species, the rate constant for electron transfer between the heme and the electrode increases for the acidic conformer, which is also found to act as a biocatalytic interface for dioxygen reduction.
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Affiliation(s)
- Carlo Augusto Bortolotti
- Department of Chemistry and SCS Center, University of Modena and Reggio Emilia, Via Campi 183, I-41100 Modena, Italy
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37
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38
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Battistuzzi G, Bellei M, Borsari M, Di Rocco G, Ranieri A, Sola M. Axial ligation and polypeptide matrix effects on the reduction potential of heme proteins probed on their cyanide adducts. J Biol Inorg Chem 2005; 10:643-51. [PMID: 16133205 DOI: 10.1007/s00775-005-0014-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Accepted: 07/25/2005] [Indexed: 10/25/2022]
Abstract
The enthalpic and entropic changes accompanying the reduction reaction of the six-coordinate cyanide adducts of cytochrome c, microperoxidase-11 and a few plant peroxidases were measured electrochemically. Once the compensating changes in reduction enthalpy and entropy due to solvent reorganization effects are factorized out, it is found that cyanide binding stabilizes enthalpically the ferriheme following the order: cyochrome c > peroxidase > microperoxidase-11. The effect is inversely correlated to the solvent accessibility of the heme. Comparison of the reduction thermodynamics for the cyanide adducts of cytochrome c and plant peroxidases with those for microperoxidase-11 and myoglobin, respectively, yielded an estimate of the consequences of protein encapsulation and of the anionic character of the proximal histidine on the reduction potential of the heme-cyanide group. Insertion of the heme-CN group into the folded peptide chain of cyt c induces an enthalpy-based decrease in E degrees ' of approximately 100 mV, consistent with the lower net charge of the oxidized as compared to the reduced iron center, whereas a full imidazolate character of the proximal histidine stabilizes enthalpically the ferriheme by approximately 400 mV. The latter value should be best considered as an upper limit since it also includes some solvation effects arising from the nature of the protein systems being compared.
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Affiliation(s)
- G Battistuzzi
- Department of Chemistry and Centro SCS, University of Modena and Reggio Emilia, via Campi 183, 41100, Modena, Italy
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39
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Chi Q, Farver O, Ulstrup J. Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance. Proc Natl Acad Sci U S A 2005; 102:16203-8. [PMID: 16260751 PMCID: PMC1275599 DOI: 10.1073/pnas.0508257102] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi-biological environment, suitable for detailed observations of long-range protein interfacial ET at the nanoscale and single-molecule levels. Because azurin is located at clearly identifiable fixed sites in well controlled orientation, the ET configuration parallels biological ET. The ET is nonadiabatic, and the rate constants display tunneling features with distance-decay factors of 0.83 and 0.91 A(-1) in H(2)O and D(2)O, respectively. Redox-gated tunneling resonance is observed in situ at the single-molecule level by using electrochemical scanning tunneling microscopy, exhibiting an asymmetric dependence on the redox potential. Maximum resonance appears around the equilibrium redox potential of azurin with an on/off current ratio of approximately 9. Simulation analyses, based on a two-step interfacial ET model for the scanning tunneling microscopy redox process, were performed and provide quantitative information for rational understanding of the ET mechanism.
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Affiliation(s)
- Qijin Chi
- Department of Chemistry and Nano-DTU, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
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40
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Battistuzzi G, Bellei M, Leonardi A, Pierattelli R, De Candia A, Vila AJ, Sola M. Reduction thermodynamics of the T1 Cu site in plant and fungal laccases. J Biol Inorg Chem 2005; 10:867-73. [PMID: 16231129 DOI: 10.1007/s00775-005-0035-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 09/19/2005] [Indexed: 10/25/2022]
Abstract
The thermodynamic parameters for reduction of the type-1 (T1) copper site in Rhus vernicifera and Trametes versicolor laccases and for the derivative of the former protein from which the type-2 copper has been selectively removed (T2D) have been determined with UV-vis spectroelectrochemistry. In all cases, the enthalpic term turns out to be the main determinant of the Eo' of the T1 site. Also the difference between the reduction potentials of the two laccases is enthalpy-based and reflects differences in the coordination features of the T1 sites and their protein environment. The T1 sites in native R. vernicifera laccase and its T2D derivative show the same Eo', as a result of compensatory differences in the reduction thermodynamics. This suggests that removal of the type-2 (T2) copper results in modification of the reduction-induced solvent reorganization effects, with no influence in the structure of the multicopper protein site. This conclusion is supported by NMR data recorded on the native, the T2D, and Hg-substituted T1 derivatives of R. vernicifera laccase, which show that the T1 and T2/T3 sites are largely noninteracting.
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Affiliation(s)
- Gianantonio Battistuzzi
- Department of Chemistry-Centro SCS, University of Modena and Reggio Emilia, Via Campi 183, 41100, Modena, Italy.
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41
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Battistuzzi G, Borsari M, Canters GW, di Rocco G, de Waal E, Arendsen Y, Leonardi A, Ranieri A, Sola M. Ligand loop effects on the free energy change of redox and pH-dependent equilibria in cupredoxins probed on amicyanin variants. Biochemistry 2005; 44:9944-9. [PMID: 16026167 DOI: 10.1021/bi050261r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this work, we have determined the thermodynamic parameters of the reduction of four different variants of Thiobacillus versutus amicyanin by electrochemical techniques. In addition, the thermodynamic parameters were determined of the low-pH conformational change involving protonation of the C-terminal histidine ligand and the concomitant dissociation of this histidine from the Cu(I) ion. In these variants, the native C-terminal loop containing the Cys, His, and Met copper ligands has been replaced with the corresponding polypeptide segments of Pseudomonas aeruginosa azurin, Populus nigra plastocyanin, Alcaligenes faecalis S-6 pseudoazurin, and Thiobacillus ferrooxidans rusticyanin. For the reduction reaction, each loop invariably holds an entropic "memory" of the mother protein. The thermodynamics of the low-pH transition vary in a fashion that is species-dependent. When present, the memory effect again shows a large entropic component. In particular, loop elongation tends to favor the formation of the Cu(I)-His bond (hence disfavors His protonation, yielding lower pK(a) values) probably due to an increased flexibility of the loop in the reduced state. Overall, it appears that both reduction and low-pH transition are loop-responsive processes. The spacing between the ligands mostly affects the change in the conformational freedom that accompanies the reaction.
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Affiliation(s)
- Gianantonio Battistuzzi
- Department of Chemistry and SCS Center, University of Modena and Reggio Emilia, Via Campi 183, 41100 Modena, Italy
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42
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Dennison C. Ligand and loop variations at type 1 copper sites: influence on structure and reactivity. Dalton Trans 2005:3436-42. [PMID: 16234922 DOI: 10.1039/b507440c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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Affiliation(s)
- Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, UK NE2 4HH.
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43
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Nakamura A, Suzawa T, Kato Y, Watanabe T. Significant species-dependence of P700 redox potential as verified by spectroelectrochemistry: Comparison of spinach andTheromosynechococcus elongatus. FEBS Lett 2005; 579:2273-6. [PMID: 15848157 DOI: 10.1016/j.febslet.2005.02.076] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Revised: 02/27/2005] [Accepted: 03/04/2005] [Indexed: 10/25/2022]
Abstract
The redox potentials of P700, the primary electron donor of photosystem (PS) I, of spinach and Thermosynechococcus elongatus were determined by means of spectroelectrochemistry with an error range of +/-2-3 mV, to find that the redox potential of P700 in T. elongatus is lower by ca. 50 mV as compared with spinach. The shift in the P700 redox potential of PS I core particles prepared by harsh detergent treatments remained to within 10 mV for both organisms. These results show that the 50 mV difference in the P700 redox potential between the two organisms is not a detergent-induced artifact but reflects an intrinsic property of each PS I.
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Affiliation(s)
- Akimasa Nakamura
- Institute of Industrial Science, The University of Tokyo, Japan.
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44
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van den Bosch M, Swart M, Snijders JG, Berendsen HJC, Mark AE, Oostenbrink C, van Gunsteren WF, Canters GW. Calculation of the Redox Potential of the Protein Azurin and Some Mutants. Chembiochem 2005; 6:738-46. [PMID: 15747387 DOI: 10.1002/cbic.200400244] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Azurin from Pseudomonas aeruginosa is a small 128-residue, copper-containing protein. Its redox potential can be modified by mutating the protein. Free-energy calculations based on classical molecular-dynamics simulations of the protein and from mutants in aqueous solution at different pH values were used to compute relative redox potentials. The precision of the free-energy calculations with the lambda coupling-parameter approach is evaluated as function of the number and sequence of lambda values, the sampling time and initial conditions. It is found that the precision is critically dependent on the relaxation of hydrogen-bonding networks when changing the atomic-charge distribution due to a change of redox state or pH value. The errors in the free energies range from 1 to 10 k(B)T, depending on the type of process. Only qualitative estimates of the change in redox potential by protein mutation can be obtained.
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Affiliation(s)
- Marieke van den Bosch
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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45
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Liu X, Huang Y, Zhang W, Fan G, Fan C, Li G. Electrochemical investigation of redox thermodynamics of immobilized myoglobin: ionic and ligation effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:375-378. [PMID: 15620327 DOI: 10.1021/la047928f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this study, we investigated redox thermodynamics of myoglobin as well as the ionic (phosphate ions) and ligation (imidazole) effects via a dynamic electrochemical approach. We employed a previously established system that features nonmediated, direct electrochemistry of myoglobin and myoglobin in an immobilized state (i.e., diffusionless electrochemistry). Thermodynamics parameters were obtained by measuring redox potential (E degrees ') of myoglobin at varied temperature (T), in the presence and in the absence of specific ions or axial ligands. As a step further, we evaluated contributions from allosteric effect and axial iron ligation by partitioning E degrees ' changes into entropic and enthalpic terms. Compensation phenomena between the entropic and enthalpic changes were observed in all these cases. On the basis of these studies, we also correlated these phenomena to possible structural variations.
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Affiliation(s)
- Xinjian Liu
- Department of Biochemistry and National Key Laboratory of Pharmaceutical, Biotechnology, Nanjing University, Nanjing 210093, People's Republic of China
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46
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Fujita K, Nakamura N, Ohno H, Leigh BS, Niki K, Gray HB, Richards JH. Mimicking Protein−Protein Electron Transfer: Voltammetry of Pseudomonas aeruginosa Azurin and the Thermus thermophilus CuA Domain at ω-Derivatized Self-Assembled-Monolayer Gold Electrodes. J Am Chem Soc 2004; 126:13954-61. [PMID: 15506756 DOI: 10.1021/ja047875o] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Well-defined voltammetric responses of redox proteins with acidic-to-neutral pI values have been obtained on pure alkanethiol as well as on mixed self-assembled-monolayer (SAM) omega-derivatized alkanethiol/gold bead electrodes. Both azurin (P. aeruginosa) (pI = 5.6) and subunit II (Cu(A) domain) of ba(3)-type cytochrome c oxidase (T. thermophilus) (pI = 6.0) exhibit optimal voltammetric responses on 1:1 mixtures of [H(3)C(CH(2))(n)()SH + HO(CH(2))(n)()SH] SAMs. The electron transfer (ET) rate vs distance behavior of azurin and Cu(A) is independent of the omega-derivatized alkanethiol SAM headgroups. Strikingly, only wild-type azurin and mutants containing Trp48 give voltammetric responses: based on modeling, we suggest that electronic coupling with the SAM headgroup (H(3)C- and/or HO-) occurs at the Asn47 side chain carbonyl oxygen and that an Asn47-Cys112 hydrogen bond promotes intramolecular ET to the copper. Inspection of models also indicates that the Cu(A) domain of ba(3)-type cytochrome c oxidase is coupled to the SAM headgroup (H(3)C- and/or HO-) near the main chain carbonyl oxygen of Cys153 and that Phe88 (analogous to Trp143 in subunit II of cytochrome c oxidase from R. sphaeroides) is not involved in the dominant tunneling pathway. Our work suggests that hydrogen bonds from hydroxyl or other proton-donor groups to carbonyl oxygens potentially can facilitate intermolecular ET between physiological redox partners.
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Affiliation(s)
- Kyoko Fujita
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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47
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Battistuzzi G, Borsari M, Ranieri A, Sola M. Solvent-based deuterium isotope effects on the redox thermodynamics of cytochrome c. J Biol Inorg Chem 2004; 9:781-7. [PMID: 15278784 DOI: 10.1007/s00775-004-0580-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 06/29/2004] [Indexed: 10/26/2022]
Abstract
The reduction thermodynamics of cytochrome c (cytc), determined electrochemically, are found to be sensitive to solvent H/D isotope effects. Reduction of cytochrome c is enthalpically more favored in D(2)O with respect to H(2)O, but is disfavored on entropic grounds. This is consistent with a reduction-induced strengthening of the H-bonding network within the hydration sphere of the protein. No significant changes in E degrees ' occur, since the above variations are compensative. As a main result, this work shows that the oxidation-state-dependent differences in protein solvation, including electrostatics and solvent reorganization effects, play an important role in determining the individual enthalpy and entropy changes of the reduction process. It is conceivable that this is a common thermodynamic feature of all electron transport metalloproteins. The isotope effects turn out to be sensitive to buffer anions which specifically bind to cytc. Evidence is gained that the solvation thermodynamics of both redox forms of cytc are sensibly affected by strongly hydrated anions.
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Affiliation(s)
- G Battistuzzi
- Department of Chemistry and Centro SCS, University of Modena and Reggio Emilia, Via Campi 183, 41100 Modena, Italy
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48
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Redox thermodynamics of cytochrome c adsorbed on mercaptoundecanol monolayer electrodes. J Electroanal Chem (Lausanne) 2004. [DOI: 10.1016/j.jelechem.2003.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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49
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Harrison MD, Dennison C. Characterization of Arabidopsis thaliana stellacyanin: A comparison with umecyanin. Proteins 2004; 55:426-35. [PMID: 15048833 DOI: 10.1002/prot.20017] [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: 12/12/2022]
Abstract
The cupredoxin domain of a putative type 1 blue copper protein (BCB) from Arabidopsis thaliana was overexpressed and purified. A recursive polymerase chain reaction method was used to synthesize an artificial coding region for the cupredoxin domain of horseradish stellacyanin (commonly known as umecyanin), prior to overexpression and purification. The recombinant proteins were refolded from inclusion bodies and reconstituted with copper, and their in vitro characteristics were studied. Recombinant umecyanin, which is nonglycosylated, has identical spectroscopic and redox properties to the native protein. The UV/Vis and EPR spectra of recombinant BCB and umecyanin demonstrate that they have comparable axial type 1 copper binding sites. Paramagnetic (1)H NMR spectroscopy highlights the similarity between the active site architectures of BCB and umecyanin. The reduction potential of recombinant BCB is 252 mV, compared to 293 mV for recombinant umecyanin. Identical pK(a) values of 9.7 are obtained for the alkaline transitions in both proteins. This study demonstrates that BCB is the A. thaliana stellacyanin and the results form the biochemical basis for a discussion of BCB function in the model vascular plant.
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Affiliation(s)
- Mark D Harrison
- School of Natural Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
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50
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Affiliation(s)
- David B Rorabacher
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
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