1
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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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2
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Lancellotti L, Borsari M, Bellei M, Bonifacio A, Bortolotti CA, Di Rocco G, Ranieri A, Sola M, Battistuzzi G. Urea-induced denaturation of immobilized yeast iso-1 cytochrome c: Role of Met80 and Tyr67 in the thermodynamics of unfolding and promotion of pseudoperoxidase and nitrite reductase activities. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.137237] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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3
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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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4
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Gu J, Shin DW, Pletneva EV. Remote Perturbations in Tertiary Contacts Trigger Ligation of Lysine to the Heme Iron in Cytochrome c. Biochemistry 2017; 56:2950-2966. [PMID: 28474881 DOI: 10.1021/acs.biochem.6b01187] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Perturbations in protein structure define the mechanism of allosteric regulation and biological information transfer. In cytochrome c (cyt c), ligation of Met80 to the heme iron is critical for the protein's electron-transfer (ET) function in oxidative phosphorylation and for suppressing its peroxidase activity in apoptosis. The hard base Lys is a better match for the hard ferric iron than the soft base Met is, suggesting the key role of the protein scaffold in favoring Met ligation. To probe the role of the protein structure in the maintenance of Met ligation, mutations T49V and Y67R/M80A were designed to disrupt hydrogen bonding and packing of the heme coordination loop, respectively. Electronic absorption, nuclear magnetic resonance, and electron paramagnetic resonance spectra reveal that ferric forms of both variants are Lys-ligated at neutral pH. A minor change in the tertiary contacts in T49V, away from the heme coordination loop, appears to be sufficient to execute a change in ligation, suggesting a cross-talk between the different regions of the protein structure and a possibility of built-in conformational switches in cyt c. Analyses of thermodynamic stability, kinetics of Lys binding and dissociation, and the pH-dependent changes in ligation provide a detailed characterization of the Lys coordination in these variants and relate these properties to the extent of structural perturbations. The findings emphasize the importance of the hydrogen-bonding network in controlling ligation of the native Met80 to the heme iron.
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Affiliation(s)
- Jie Gu
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
| | - Dong-Woo Shin
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
| | - Ekaterina V Pletneva
- Department of Chemistry, Dartmouth College , Hanover, New Hampshire 03755, United States
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5
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Hannibal L, Tomasina F, Capdevila DA, Demicheli V, Tórtora V, Alvarez-Paggi D, Jemmerson R, Murgida DH, Radi R. Alternative Conformations of Cytochrome c: Structure, Function, and Detection. Biochemistry 2016; 55:407-28. [DOI: 10.1021/acs.biochem.5b01385] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Luciana Hannibal
- Departamento
de Bioquímica, Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Center
for Pediatrics and Adolescent Medicine, Medical Center, University of Freiburg, Mathildenstrasse 1, Freiburg D-79106, Germany
| | - Florencia Tomasina
- Departamento
de Bioquímica, Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
| | - Daiana A. Capdevila
- Departamento
de Química Inorgánica, Analítica y Química
Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Verónica Demicheli
- Departamento
de Bioquímica, Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
| | - Verónica Tórtora
- Departamento
de Bioquímica, Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
| | - Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Ronald Jemmerson
- Department
of Microbiology and Immunology, University of Minnesota, MMC 196,
420 Delaware Street, Southeast, Minneapolis, Minnesota 55455, United States
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Rafael Radi
- Departamento
de Bioquímica, Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
- Centro
de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800 Montevideo, Uruguay
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6
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Tognaccini L, Ciaccio C, D'Oria V, Cervelli M, Howes BD, Coletta M, Mariottini P, Smulevich G, Fiorucci L. Structure-function relationships in human cytochrome c: The role of tyrosine 67. J Inorg Biochem 2015; 155:56-66. [PMID: 26610191 DOI: 10.1016/j.jinorgbio.2015.11.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 11/03/2015] [Accepted: 11/10/2015] [Indexed: 11/20/2022]
Abstract
Spectroscopic and functional properties of human cytochrome c and its Tyr67 residue mutants (i.e., Tyr67His and Tyr67Arg) have been investigated. In the case of the Tyr67His mutant, we have observed only a very limited structural alteration of the heme pocket and of the Ω-loop involving, among others, the residue Met80 and its bond with the heme iron. Conversely, in the Tyr67Arg mutant the Fe-Met80 bond is cleaved; consequently, a much more extensive structural alteration of the Ω-loop can be envisaged. The structural, and thus the functional modifications, of the Tyr67Arg mutant are present in both the ferric [Fe(III)] and the ferrous [Fe(II)] forms, indicating that the structural changes are independent of the heme iron oxidation state, depending instead on the type of substituting residue. Furthermore, a significant peroxidase activity is evident for the Tyr67Arg mutant, highlighting the role of Arg as a basic, positively charged residue at pH7.0, located in the heme distal pocket, which may act as an acid to cleave the O-O bond in H2O2. As a whole, our results indicate that a delicate equilibrium is associated with the spatial arrangement of the Ω-loop. Clearly, Arg, but not His, is able to stabilize and polarize the negative charge on the Fe(III)-OOH complex during the formation of Compound I, with important consequences on cytochrome peroxidation activity and its role in the apoptotic process, which is somewhat different in yeast and mammals.
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Affiliation(s)
- Lorenzo Tognaccini
- Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino, FI, Italy
| | - Chiara Ciaccio
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems (CIRCMSB), Bari, Italy
| | - Valentina D'Oria
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
| | | | - Barry D Howes
- Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino, FI, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems (CIRCMSB), Bari, Italy
| | | | - Giulietta Smulevich
- Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino, FI, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems (CIRCMSB), Bari, Italy.
| | - Laura Fiorucci
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy.
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7
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Alvarez-Paggi D, Zitare U, Murgida DH. The role of protein dynamics and thermal fluctuations in regulating cytochrome c/cytochrome c oxidase electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1196-207. [PMID: 24502917 DOI: 10.1016/j.bbabio.2014.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/22/2014] [Accepted: 01/28/2014] [Indexed: 01/06/2023]
Abstract
In this overview we present recent combined electrochemical, spectroelectrochemical, spectroscopic and computational studies from our group on the electron transfer reactions of cytochrome c and of the primary electron acceptor of cytochrome c oxidase, the CuA site, in biomimetic complexes. Based on these results, we discuss how protein dynamics and thermal fluctuations may impact on protein ET reactions, comment on the possible physiological relevance of these results, and finally propose a regulatory mechanism that may operate in the Cyt/CcO electron transfer reaction in vivo. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
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Affiliation(s)
- Damian Alvarez-Paggi
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina
| | - Ulises Zitare
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina
| | - Daniel H Murgida
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina.
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8
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Zaidi S, Hassan MI, Islam A, Ahmad F. The role of key residues in structure, function, and stability of cytochrome-c. Cell Mol Life Sci 2014; 71:229-55. [PMID: 23615770 PMCID: PMC11113841 DOI: 10.1007/s00018-013-1341-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/05/2013] [Accepted: 04/08/2013] [Indexed: 02/06/2023]
Abstract
Cytochrome-c (cyt-c), a multi-functional protein, plays a significant role in the electron transport chain, and thus is indispensable in the energy-production process. Besides being an important component in apoptosis, it detoxifies reactive oxygen species. Two hundred and eighty-five complete amino acid sequences of cyt-c from different species are known. Sequence analysis suggests that the number of amino acid residues in most mitochondrial cyts-c is in the range 104 ± 10, and amino acid residues at only few positions are highly conserved throughout evolution. These highly conserved residues are Cys14, Cys17, His18, Gly29, Pro30, Gly41, Asn52, Trp59, Tyr67, Leu68, Pro71, Pro76, Thr78, Met80, and Phe82. These are also known as "key residues", which contribute significantly to the structure, function, folding, and stability of cyt-c. The three-dimensional structure of cyt-c from ten eukaryotic species have been determined using X-ray diffraction studies. Structure analysis suggests that the tertiary structure of cyt-c is almost preserved along the evolutionary scale. Furthermore, residues of N/C-terminal helices Gly6, Phe10, Leu94, and Tyr97 interact with each other in a specific manner, forming an evolutionary conserved interface. To understand the role of evolutionary conserved residues on structure, stability, and function, numerous studies have been performed in which these residues were substituted with different amino acids. In these studies, structure deals with the effect of mutation on secondary and tertiary structure measured by spectroscopic techniques; stability deals with the effect of mutation on T m (midpoint of heat denaturation), ∆G D (Gibbs free energy change on denaturation) and folding; and function deals with the effect of mutation on electron transport, apoptosis, cell growth, and protein expression. In this review, we have compiled all these studies at one place. This compilation will be useful to biochemists and biophysicists interested in understanding the importance of conservation of certain residues throughout the evolution in preserving the structure, function, and stability in proteins.
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Affiliation(s)
- Sobia Zaidi
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Md. Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Faizan Ahmad
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
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9
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Alvarez-Paggi D, Castro MA, Tórtora V, Castro L, Radi R, Murgida DH. Electrostatically Driven Second-Sphere Ligand Switch between High and Low Reorganization Energy Forms of Native Cytochrome c. J Am Chem Soc 2013; 135:4389-97. [DOI: 10.1021/ja311786b] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Verónica Tórtora
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Laura Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Rafael Radi
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and ‡INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA-Buenos Aires, Argentina
- Departamento
de Bioquímica and ⊥Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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10
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Battistuzzi G, Bortolotti CA, Bellei M, Di Rocco G, Salewski J, Hildebrandt P, Sola M. Role of Met80 and Tyr67 in the Low-pH Conformational Equilibria of Cytochrome c. Biochemistry 2012; 51:5967-78. [DOI: 10.1021/bi3007302] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gianantonio Battistuzzi
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Carlo Augusto Bortolotti
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Marzia Bellei
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Giulia Di Rocco
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Johannes Salewski
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Marco Sola
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
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11
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Yu XW, Li YQ. Kinetics and thermodynamics of synthesis of propyl gallate by mycelium-bound tannase from Aspergillus niger in organic solvent. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.molcatb.2006.02.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Naidu GN, Panda T. Studies on pH and thermal deactivation of pectolytic enzymes from Aspergillus niger. Biochem Eng J 2003. [DOI: 10.1016/s1369-703x(03)00022-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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14
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Battistuzzi G, Borsari M, Ranieri A, Sola M. Conservation of the free energy change of the alkaline isomerization in mitochondrial and bacterial cytochromes c. Arch Biochem Biophys 2002; 404:227-33. [PMID: 12147260 DOI: 10.1016/s0003-9861(02)00283-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The thermodynamic parameters of the alkaline transition for oxidized native yeast iso-1 cytochrome c and Rhodopseudomonas palustris cytochrome c(2) (cytc(2)) have been determined through direct electrochemistry experiments carried out at variable pH and temperature and compared to those for horse and beef heart cytochromes c. We have found that both transition enthalpy and entropy are remarkably species dependent, following the order R. palustris cytc(2) >> beef (horse) heart cytc>yeast iso-1 cytc. Considering the high homology at the heme-protein interface in the native species, this variability is likely to be mainly determined by differences in the structural and solvation properties and the relative abundance of the various alkaline conformers. Notably, changes in transition enthalpy and entropy among these cytochromes c are compensative and result in small variations in the free energy change of the process (which amounts approximately to +50 kJ mol(-1)) and consequently in the apparent pK(a) value. This compensation indicates that solvent reorganization effects play an important role in the thermodynamics of the transition. This mechanism is functional to ensure a relatively high pK(a) value for the alkaline transition, which is needed to preserve His,Met ligation to the heme iron in cytochrome c at physiological pH and temperature, hence the E(o) value required for the biological function.
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Affiliation(s)
- Gianantonio Battistuzzi
- Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41100, Modena, Italy
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15
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Benini S, González A, Rypniewski WR, Wilson KS, Van Beeumen JJ, Ciurli S. Crystal structure of oxidized Bacillus pasteurii cytochrome c553 at 0.97-A resolution. Biochemistry 2000; 39:13115-26. [PMID: 11052663 DOI: 10.1021/bi000402j] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This article reports the first X-ray structure of the soluble form of a c-type cytochrome isolated from a Gram-positive bacterium. Bacillus pasteurii cytochrome c(553), characterized by a low reduction potential and by a low sequence homology with cytochromes from Gram-negative bacteria or eukaryotes, is a useful case study for understanding the structure-function relationships for this class of electron-transfer proteins. Diffraction data on a single crystal of cytochrome c(553) were obtained using synchrotron radiation at 100 K. The structure was determined at 0.97-A resolution using ab initio phasing and independently at 1.70 A in an MAD experiment. In both experiments, the structure solution exploited the presence of a single Fe atom as anomalous scatterer in the protein. For the 0.97-A data, the phasing was based on a single data set. This is the most precise structure of a heme protein to date. The crystallized cytochrome c(553) contains only 71 of the 92 residues expected from the intact protein sequence, lacking the first 21 amino acids at the N-terminus. This feature is consistent with previous evidence that this tail, responsible for anchoring the protein to the cytoplasm membrane, is easily cleaved off during the purification procedure. The heme prosthetic group in B. pasteurii cytochrome c(553) is surrounded by three alpha-helices in a compact arrangement. The largely exposed c-type heme group features a His-Met axial coordination of the Fe(III) ion. The protein is characterized by a very asymmetric charge distribution, with the exposed heme edge located on a surface patch devoid of net charges. A structural search of a representative set of protein structures reveals that B. pasteurii cytochrome c(553) is most similar to Pseudomonas cytochromes c(551), followed by cytochromes c(6), Desulfovibrio cytochrome c(553), cytochromes c(552) from thermophiles, and cytochromes c from eukaryotes. Notwithstanding a low sequence homology, a structure-based alignment of these cytochromes shows conservation of three helical regions, with different additional secondary structure motifs characterizing each protein. In B. pasteurii cytochrome c(553), these motifs are represented by the shortest interhelix connecting fragments observed for this group of proteins. The possible relationships between heme solvent accessibility and the electrochemical reduction potential are discussed.
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Affiliation(s)
- S Benini
- European Molecular Biology Laboratory, c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany
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16
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