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Zhou Z, Arroum T, Luo X, Kang R, Lee YJ, Tang D, Hüttemann M, Song X. Diverse functions of cytochrome c in cell death and disease. Cell Death Differ 2024; 31:387-404. [PMID: 38521844 PMCID: PMC11043370 DOI: 10.1038/s41418-024-01284-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 03/13/2024] [Accepted: 03/18/2024] [Indexed: 03/25/2024] Open
Abstract
The redox-active protein cytochrome c is a highly positively charged hemoglobin that regulates cell fate decisions of life and death. Under normal physiological conditions, cytochrome c is localized in the mitochondrial intermembrane space, and its distribution can extend to the cytosol, nucleus, and extracellular space under specific pathological or stress-induced conditions. In the mitochondria, cytochrome c acts as an electron carrier in the electron transport chain, facilitating adenosine triphosphate synthesis, regulating cardiolipin peroxidation, and influencing reactive oxygen species dynamics. Upon cellular stress, it can be released into the cytosol, where it interacts with apoptotic peptidase activator 1 (APAF1) to form the apoptosome, initiating caspase-dependent apoptotic cell death. Additionally, following exposure to pro-apoptotic compounds, cytochrome c contributes to the survival of drug-tolerant persister cells. When translocated to the nucleus, it can induce chromatin condensation and disrupt nucleosome assembly. Upon its release into the extracellular space, cytochrome c may act as an immune mediator during cell death processes, highlighting its multifaceted role in cellular biology. In this review, we explore the diverse structural and functional aspects of cytochrome c in physiological and pathological responses. We summarize how posttranslational modifications of cytochrome c (e.g., phosphorylation, acetylation, tyrosine nitration, and oxidation), binding proteins (e.g., HIGD1A, CHCHD2, ITPR1, and nucleophosmin), and mutations (e.g., G41S, Y48H, and A51V) affect its function. Furthermore, we provide an overview of the latest advanced technologies utilized for detecting cytochrome c, along with potential therapeutic approaches related to this protein. These strategies hold tremendous promise in personalized health care, presenting opportunities for targeted interventions in a wide range of conditions, including neurodegenerative disorders, cardiovascular diseases, and cancer.
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Affiliation(s)
- Zhuan Zhou
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Tasnim Arroum
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, 48201, USA
| | - Xu Luo
- Eppley Institute for Research in Cancer and Allied Diseases, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Rui Kang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Yong J Lee
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Daolin Tang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, 48201, USA.
- Department of Biochemistry, Microbiology, and Immunology, Wayne State University, Detroit, MI, 48201, USA.
| | - Xinxin Song
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
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2
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Molecularly wiring of Cytochrome c with carboxylic acid functionalized hydroquinone on MWCNT surface and its bioelectrocatalytic reduction of H2O2 relevance to biomimetic electron-transport and redox signalling. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2020.137596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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3
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Cytochrome c: An extreme multifunctional protein with a key role in cell fate. Int J Biol Macromol 2019; 136:1237-1246. [DOI: 10.1016/j.ijbiomac.2019.06.180] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 01/25/2023]
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4
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Ascenzi P, De Simone G, Ciaccio C, Santucci R, Coletta M. Hydroxylamine-induced oxidation of ferrous CO-bound carboxymethylated-cytochrome c. J PORPHYR PHTHALOCYA 2018. [DOI: 10.1142/s1088424618501055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The hexa-coordinated metal center of horse heart cyt[Formula: see text] (cyt[Formula: see text] is at the root of its low reactivity. In contrast, carboxymethylated cyt[Formula: see text] (CM-cyt[Formula: see text] displays myoglobin-like properties. Herein, kinetics of CO binding to ferrous CM-cyt[Formula: see text] (CM-cyt[Formula: see text](II)) and of the irreversible oxidation of ferrous carbonylated CM-cyt[Formula: see text] (CM-cyt[Formula: see text](II)-CO) by hydroxylamine (HA), at pH 5.8 and 20.0 [Formula: see text]C, are reported. HA irreversibly oxidizes CM-cyt[Formula: see text](II)-CO with the 1:2 stoichiometry leading to the formation of the ferric species (CM-cyt[Formula: see text](III)) without the observation of intermediates. Present data indicate that: (i) the rate of CO dissociation from CM-cyt[Formula: see text](II)-CO represents the rate-limiting step of HA-mediated oxidation of the carbonylated metal center, (ii) the fast oxidation of CM-cyt[Formula: see text](II)-CO from HA reflects the penta-coordination of the transient CM-cyt[Formula: see text](II) species, (iii) the HA-catalyzed conversion of CM-cyt[Formula: see text](II)-CO to CM-cyt[Formula: see text](III) could proceed via the geminate mechanism, (iv) values of the second-order rate constants for the carbonylation and the HA-mediated oxidation of ferrous heme-proteins are linearly correlated reflecting the penta- or hexa-coordination of the metal center, the free energy for the in-plane positioning of the heme-Fe atom in the unliganded species, and the arrangement of the distal portion of the heme pocket that affects ligand and/or electron transfer.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, I-00146 Roma, Italy
| | | | - Chiara Ciaccio
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
| | - Roberto Santucci
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, I-00133 Roma, Italy
- Interuniversity Consortium for the Research on Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
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5
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Lawrence G, Kalimuthu P, Benzigar M, Shelat KJ, Lakhi KS, Park DH, Ji Q, Ariga K, Bernhardt PV, Vinu A. A Nanoporous Cytochrome c Film with Highly Ordered Porous Structure for Sensing of Toxic Vapors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1702295. [PMID: 28961349 DOI: 10.1002/adma.201702295] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/08/2017] [Indexed: 06/07/2023]
Abstract
Creating well-ordered nanoporosity in biomolecules promises stability and activity, offering access to an even wider range of application possibilities. Here, the preparation of nanoporous protein films containing cytochrome c protein molecules is reported through a soft-templating strategy using polystyrene (PS) spheres of different sizes as templates. The stability of the cytochrome c film is demonstrated through electrochemistry studies to show a reusable nature of these films over a long period of time. The size of the PS spheres is varied to tune the pore diameter and the thickness of the cytochrome c films, which are quite stable and highly selective for sensing toxic acidic vapors. The fusion of the templating strategy and the self-assembly of biomolecules may offer various possibilities by generating a new series of porous biomolecules including enzymes with different molecular weights and diameters, peptides, antibodies, and DNA with interesting catalytic, adsorption, sensing, and electronic properties.
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Affiliation(s)
- Geoffrey Lawrence
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Mercy Benzigar
- Future Industries Institute, University of South Australia, Mawson Lakes, Adelaide, 5095, SA, Australia
| | - Kinnari J Shelat
- Australian National Fabrication Facilities - Queensland Node, The University of Queensland, 75 Corner College and Cooper Road, Brisbane, 4072, QLD, Australia
| | - Kripal S Lakhi
- Future Industries Institute, University of South Australia, Mawson Lakes, Adelaide, 5095, SA, Australia
| | - Dae-Hwan Park
- Future Industries Institute, University of South Australia, Mawson Lakes, Adelaide, 5095, SA, Australia
| | - Qingmin Ji
- World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Katsuhiko Ariga
- World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Ajayan Vinu
- Future Industries Institute, University of South Australia, Mawson Lakes, Adelaide, 5095, SA, Australia
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6
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Alvarez-Paggi D, Hannibal L, Castro MA, Oviedo-Rouco S, Demicheli V, Tórtora V, Tomasina F, Radi R, Murgida DH. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog. Chem Rev 2017; 117:13382-13460. [DOI: 10.1021/acs.chemrev.7b00257] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Luciana Hannibal
- Department
of Pediatrics, Universitätsklinikum Freiburg, Mathildenstrasse 1, Freiburg 79106, Germany
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Santiago Oviedo-Rouco
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Veronica Demicheli
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Veronica Tórtora
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Florencia Tomasina
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Rafael Radi
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
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7
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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: 105] [Impact Index Per Article: 10.5] [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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Bosserdt M, Gajovic-Eichelman N, Scheller FW. Modulation of direct electron transfer of cytochrome c by use of a molecularly imprinted thin film. Anal Bioanal Chem 2013; 405:6437-44. [PMID: 23660694 DOI: 10.1007/s00216-013-7009-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/26/2013] [Accepted: 04/19/2013] [Indexed: 11/26/2022]
Abstract
We describe the preparation of a molecularly imprinted polymer film (MIP) on top of a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold, where the template cytochrome c (cyt c) participates in direct electron transfer (DET) with the underlying electrode. To enable DET, a non-conductive polymer film is electrodeposited from an aqueous solution of scopoletin and cyt c on to the surface of a gold electrode previously modified with MUA. The electroactive surface concentration of cyt c was 0.5 pmol cm(-2). In the absence of the MUA layer, no cyt c DET was observed and the pseudo-peroxidatic activity of the scopoletin-entrapped protein, assessed via oxidation of Ampliflu red in the presence of hydrogen peroxide, was only 30% of that for the MIP on MUA. This result indicates that electrostatic adsorption of cyt c by the MUA-SAM substantially increases the surface concentration of cyt c during the electrodeposition step, and is a prerequisite for the productive orientation required for DET. After template removal by treatment with sulfuric acid, rebinding of cyt c to the MUA-MIP-modified electrode occurred with an affinity constant of 100,000 mol(-1) L, a value three times higher than that determined by use of fluorescence titration for the interaction between scopoletin and cyt c in solution. The DET of cyt c in the presence of myoglobin, lysozyme, and bovine serum albumin (BSA) reveals that the MIP layer suppresses the effect of competing proteins.
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Affiliation(s)
- Maria Bosserdt
- Institute of Biochemistry and Biology, University of Potsdam, Golm, Germany
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10
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Nakamura S, Kidokoro SI. Volumetric Properties of the Molten Globule State of Cytochrome c in the Thermal Three-State Transition Evaluated by Pressure Perturbation Calorimetry. J Phys Chem B 2012; 116:1927-32. [DOI: 10.1021/jp209686e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
| | - Shun-ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
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11
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Nakamura S, Seki Y, Katoh E, Kidokoro SI. Thermodynamic and structural properties of the acid molten globule state of horse cytochrome C. Biochemistry 2011; 50:3116-26. [PMID: 21388230 DOI: 10.1021/bi101806b] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To understand the stabilization, folding, and functional mechanisms of proteins, it is very important to understand the structural and thermodynamic properties of the molten globule state. In this study, the global structure of the acid molten globule state, which we call MG1, of horse cytochrome c at low pH and high salt concentrations was evaluated by solution X-ray scattering (SXS), dynamic light scattering, and circular dichroism measurements. MG1 was globular and slightly (3%) larger than the native state, N. Calorimetric methods, such as differential scanning calorimetry and isothermal acid-titration calorimetry, were used to evaluate the thermodynamic parameters in the transitions of N to MG1 and MG1 to denatured state D of horse cytochrome c. The heat capacity change, ΔC(p), in the N-to-MG1 transition was determined to be 2.56 kJ K(-1) mol(-1), indicating the increase in the level of hydration in the MG1 state. Moreover, the intermediate state on the thermal N-to-D transition of horse cytochrome c at pH 4 under low-salt conditions showed the same structural and thermodynamic properties of the MG1 state in both SXS and calorimetric measurements. The Gibbs free energy changes (ΔG) for the N-to-MG1 and N-to-D transitions at 15 °C were 10.9 and 42.2 kJ mol(-1), respectively.
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Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
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12
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Direct probing of the folding/unfolding event of bovine hemoglobin at montmorillonite clay modified electrode by adsorptive-transfer voltammetry. Talanta 2011; 84:148-54. [DOI: 10.1016/j.talanta.2010.12.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Revised: 12/16/2010] [Accepted: 12/21/2010] [Indexed: 11/22/2022]
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13
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Khan MKA, Rahaman H, Ahmad F. Conformation and thermodynamic stability of pre-molten and molten globule states of mammalian cytochromes-c. Metallomics 2011; 3:327-38. [DOI: 10.1039/c0mt00078g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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14
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Wu C, Xu B, Zhao J, Jiang Q, Wei F, Jiang H, Wang X, Yan H. Ferrocene-Substituted Dithio-o-Carborane Isomers: Influence on the Native Conformation of Myoglobin Protein. Chemistry 2010; 16:8914-22. [DOI: 10.1002/chem.201000605] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Herzog G, Eichelmann-Daly P, Arrigan DW. Electrochemical behaviour of denatured haemoglobin at the liquid|liquid interface. Electrochem commun 2010. [DOI: 10.1016/j.elecom.2009.12.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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16
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Li X, Zheng W, Zhang L, Yu P, Lin Y, Su L, Mao L. Effective Electrochemical Method for Investigation of Hemoglobin Unfolding Based on the Redox Property of Heme Groups at Glassy Carbon Electrodes. Anal Chem 2009; 81:8557-63. [DOI: 10.1021/ac9015215] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Xianchan Li
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Wei Zheng
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Limin Zhang
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Ping Yu
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Yuqing Lin
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Lei Su
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
| | - Lanqun Mao
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China
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17
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Thielges MC, Zimmermann J, Dawson PE, Romesberg FE. The determinants of stability and folding in evolutionarily diverged cytochromes c. J Mol Biol 2009; 388:159-67. [PMID: 19268474 PMCID: PMC2990880 DOI: 10.1016/j.jmb.2009.02.059] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 01/25/2009] [Accepted: 02/24/2009] [Indexed: 12/01/2022]
Abstract
Cytochrome c has served as a paradigm for the study of protein stability, folding, and molecular evolution, but it remains unclear how these aspects of the protein are related. For example, while the bovine and equine cytochromes c are known to have different stabilities, and possibly different folding mechanisms, it is not known how these differences arise from just three amino acid substitutions introduced during divergence. Using site-selectively incorporated carbon-deuterium bonds, we show that like the equine protein, bovine cytochrome c is induced to unfold by guanidine hydrochloride via a stepwise mechanism, but it does not populate an intermediate as is observed with the equine protein. The increased stability also results in more similar free energies of unfolding observed at different sites within the protein, giving the appearance of a more concerted mechanism. Furthermore, we show that the differences in stability and folding appear to result from a single amino acid substitution that stabilizes a helix by allowing for increased solvation of its N-terminus.
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Affiliation(s)
- Megan C. Thielges
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Jörg Zimmermann
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Philip E. Dawson
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Floyd E. Romesberg
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
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18
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How does reorganization energy change upon protein unfolding? Monitoring the structural perturbations in the heme cavity of cytochrome c. Biophys Chem 2008; 134:225-31. [DOI: 10.1016/j.bpc.2008.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 02/17/2008] [Accepted: 02/17/2008] [Indexed: 11/21/2022]
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19
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Deriu D, Pagnotta SE, Santucci R, Rosato N. Spectroscopic and electrochemical characterization of cytochrome c encapsulated in a bio sol–gel matrix. Biometals 2007; 21:417-23. [DOI: 10.1007/s10534-007-9130-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 12/10/2007] [Indexed: 12/01/2022]
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20
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Andolfi L, Caroppi P, Bizzarri AR, Piro MC, Sinibaldi F, Ferri T, Polticelli F, Cannistraro S, Santucci R. Nanoscopic and redox characterization of engineered horse cytochrome C chemisorbed on a bare gold electrode. Protein J 2007; 26:271-9. [PMID: 17200882 DOI: 10.1007/s10930-006-9069-5] [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: 10/23/2022]
Abstract
In this paper, we exploit the potential offered by site-directed mutagenesis to achieve direct adsorption of horse cyt c on a bare gold electrode surface. To this issue, the side chain T102 has been replaced by a cysteine. T102 is close to the surface exposed C-terminal residue (E104), therefore the T102C mutation is expected to generate an exposed cysteine side chain able to facilitate protein binding to the electrode via the sulphur atom (analogously to what observed for yeast iso-1-cyt c). Scanning Tunnelling and Tapping Mode Atomic Force Microscopy measurements show that the T102C mutant stably adsorbs on an Au(111) surface and retains the morphological characteristics of the native form. Cyclic voltammetry reveals that the adsorbed variant is electroactive; however, the heterogeneous electron transfer with the electrode surface is slower than that observed for yeast iso-1-cyt c. We ascribe it to differences in the tertiary architecture of the two proteins, characterized by different flexibility and stability. In particular, the region where the N- and C-terminal helices get in contact (and where the mutation occurs) is analyzed in detail, since the interactions between these two helices are considered crucial for the stability of the overall protein fold.
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Affiliation(s)
- Laura Andolfi
- Biophysics and Nanoscience Centre, CNISM, Dipartimento di Scienze Ambientali, Università della Tuscia, 01100 Viterbo, Italy
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21
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Guo LH, Qu N. Chemical-induced unfolding of cofactor-free protein monitored by electrochemistry. Anal Chem 2007; 78:6275-8. [PMID: 16944913 DOI: 10.1021/ac060351h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein folding has been studied extensively with an aim to better understanding of the relationship between protein sequence, structure, and function. A large variety of techniques have been developed and utilized to probe protein conformation and folding/unfolding transition. In this report, electrochemical monitoring of urea-induced unfolding of a large cofactor-free protein, bovine serum albumin (BSA), is described. Enhanced electrochemical oxidation of tyrosine and tryptophan in free amino acids and in BSA was achieved on an indium tin oxide electrode by using an electron mediator, Os(bpy)2dppz (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine). The oxidation current was used as a signal reporter in the monitoring of urea-induced BSA denaturation. At high urea concentrations, the electrochemical signal increased by 3-fold relative to the native protein. The increase is attributed to the closer contact between the oxidizable residues in the unfolded BSA and Os(bpy)2dppz. The degree of unfolding assessed by electrochemistry correlates well with the established fluorescence technique in the range of 0-10 M urea. The method can be used to investigate the unfolding process of other cofactor-free proteins.
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Affiliation(s)
- Liang-Hong Guo
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Beijing 100085, China.
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22
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Sandanaraj BS, Bayraktar H, Krishnamoorthy K, Knapp MJ, Thayumanavan S. Recognition and modulation of cytochrome c's redox properties using an amphiphilic homopolymer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:3891-7. [PMID: 17315896 DOI: 10.1021/la063063p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
An amphiphilic homopolymer scaffold has been used to bind to the protein, cytochrome c. This interaction is analyzed using cyclic voltammetry, native gel electrophoresis, UV-visible absorption, and circular dichroism spectroscopy. The polymer binds to cytochrome c with micromolar affinity and the association of polymer with cytochrome c leads to a structural change of the protein. This conformational change exposes the heme unit of the protein, which affords an opportunity to reversibly modulate its electron-transfer properties. We have also shown that the electrostatic binding of polymer to cytochrome c can be used to disrupt its interaction with its natural partner, cytochrome c peroxidase.
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Affiliation(s)
- Britto S Sandanaraj
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
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23
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Nakamura S, Baba T, Kidokoro SI. A molten globule-like intermediate state detected in the thermal transition of cytochrome c under low salt concentration. Biophys Chem 2007; 127:103-12. [PMID: 17257735 DOI: 10.1016/j.bpc.2007.01.002] [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] [Received: 11/25/2006] [Revised: 01/03/2007] [Accepted: 01/04/2007] [Indexed: 11/22/2022]
Abstract
To understand the stabilization mechanism of the transient intermediate state in protein folding, it is very important to understand the structure and stability of the molten globule state under a native condition, in which the native state exists stably. The thermal transitions of horse cytochrome c were thermodynamically evaluated by highly precise differential scanning calorimetry (DSC) at pH 3.8-5.0. The heat capacity functions were analyzed using double deconvolution and the nonlinear least-squares method. An intermediate (I) state is clearly confirmed in the thermal native (N)-to-denatured (D) transition of horse cytochrome c. The mole fraction of the intermediate state shows the largest value, 0.4, at nearly 70 degrees C at pH 4.1. This intermediate state was also detected by the circular dichroism (CD) method and was found to have the properties of the molten globule-like structure by three-state analysis of the CD data. The Gibbs free-energy change between N and I, DeltaG(NI), and that between N and D, DeltaG(ND), were evaluated to be 9-22 kJ mol(-1) and 41-45 kJ mol(-1), respectively at 15( ) degrees C and pH 4.1.
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Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Japan
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24
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Dai SY, Fitzgerald MC. A mass spectrometry-based probe of equilibrium intermediates in protein-folding reactions. Biochemistry 2006; 45:12890-7. [PMID: 17042507 DOI: 10.1021/bi061295h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Described here is a mass spectrometry- and H/D exchange-based approach for the detection of equilibrium intermediate state(s) in protein-folding reactions. The approach utilizes the stability of unpurified proteins from rates of H/D exchange (SUPREX) technique to measure the m value (i.e., delta DeltaG/delta [denaturant] value) associated with the folding reaction of a protein. Such SUPREX m-value analyses can be made over a wide range of denaturant concentrations. Thus, the described approach is well-suited for the detection of high-energy intermediates that might be populated at low denaturant concentrations and hard to detect in conventional chemical denaturation experiments using spectroscopic probes. The approach is demonstrated on four known non-two-state folding proteins, including alpha-lactalbumin, cytochrome c, intestinal fatty acid binding protein (IFABP), and myoglobin. The non-two-state folding behavior of each model protein system was detected by the described method. The cytochrome c, myoglobin, and IFABP systems each had high-energy intermediate states that were undetected in conventional optical spectroscopy-based studies and previously required other more specialized biophysical approaches (e.g., nuclear magnetic resonance spectroscopy-based methods and protease protection assays) for their detection. The SUPREX-based approach outlined here offers an attractive alternative to these other approaches, because it has the advantage of speed and the ability to analyze both purified and unpurified protein samples in either concentrated or dilute solution.
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Affiliation(s)
- Susie Y Dai
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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25
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Latypov RF, Cheng H, Roder NA, Zhang J, Roder H. Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c. J Mol Biol 2006; 357:1009-25. [PMID: 16473367 DOI: 10.1016/j.jmb.2006.01.055] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 01/11/2006] [Accepted: 01/15/2006] [Indexed: 10/25/2022]
Abstract
Although the denaturant-induced unfolding transition of cytochrome c was initially thought to be a cooperative process, recent spectroscopic studies have shown deviations from two-state behavior consistent with accumulation of an equilibrium intermediate. However, little is known about the structural and thermodynamic properties of this state, and whether it is stabilized by the presence of non-native heme ligands. We monitored the reversible denaturant-induced unfolding equilibrium of oxidized horse cytochrome c using various spectroscopic probes, including fluorescence, near and far-UV CD, heme absorbance bands in the Soret, visible and near-IR regions of the spectrum, as well as 2D NMR. Global fitting techniques were used for a quantitative interpretation of the results in terms of a three-state model, which enabled us to determine the intrinsic spectroscopic properties of the intermediate. A well-populated intermediate was observed in equilibrium experiments at pH 5 using either guanidine-HCl or urea as a denaturant, both for wild-type cytochrome c as well as an H33N mutant chosen to prevent formation of non-native His-heme ligation. For a more detailed structural characterization of the intermediate, we used 2D 1H-15N correlation spectroscopy to follow the changes in peak intensity for individual backbone amide groups. The equilibrium state observed in our optical and NMR studies contains many native-like structural features, including a well-structured alpha-helical sub-domain, a short Trp59-heme distance and solvent-shielded heme environment, but lacks the native Met80 sulfur-iron linkage and shows major perturbations in side-chain packing and other tertiary interactions. These structural properties are reminiscent of the A-state of cytochrome c, a compact denatured form found under acidic high-salt conditions, as well as a kinetic intermediate populated at a late stage of folding. The denaturant-induced intermediate also resembles alkaline forms of cytochrome c with altered heme ligation, suggesting that disruption of the native methionine ligand favors accumulation of structurally analogous states both in the presence and absence of non-native ligands.
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Affiliation(s)
- Ramil F Latypov
- Basic Science Division, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
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26
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Fedurco M, Augustynski J, Indiani C, Smulevich G, Antalík M, Bánó M, Sedlák E, Glascock MC, Dawson JH. Electrochemistry of unfolded cytochrome c in neutral and acidic urea solutions. J Am Chem Soc 2005; 127:7638-46. [PMID: 15898816 DOI: 10.1021/ja050321g] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present investigation reports the first experimental measurements of the reorganization energy of unfolded metalloprotein in urea solution. Horse heart cytochrome c (cyt c) has been found to undergo reversible one-electron transfer reactions at pH 2 in the presence of 9 M urea. In contrast, the protein is electrochemically inactive at pH 2 under low-ionic strength conditions in the absence of urea. Urea is shown to induce ligation changes at the heme iron and lead to practically complete loss of the alpha-helical content of the protein. Despite being unfolded, the electron-transfer (ET) kinetics of cyt c on a 2-mercaptoethanol-modified Ag(111) electrode remain unusually fast and diffusion controlled. Acid titration of ferric cyt c in 9 M urea down to pH 2 is accompanied by protonation of one of the axial ligands, water binding to the heme iron (pK(a) = 5.2), and a sudden protein collapse (pH < 4). The formal redox potential of the urea-unfolded six-coordinate His18-Fe(III)-H(2)O/five-coordinate His18-Fe(II) couple at pH 2 is estimated to be -0.083 V vs NHE, about 130 mV more positive than seen for bis-His-ligated urea-denatured cyt c at pH 7. The unusually fast ET kinetics are assigned to low reorganization energy of acid/urea-unfolded cyt c at pH 2 (0.41 +/- 0.01 eV), which is actually lower than that of the native cyt c at pH 7 (0.6 +/- 0.02 eV), but closer to that of native bis-His-ligated cyt b(5) (0.44 +/- 0.02 eV). The roles of electronic coupling and heme-flattening on the rate of heterogeneous ET reactions are discussed.
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Affiliation(s)
- Milan Fedurco
- Department of Chemistry, University of Geneva, Switzerland
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27
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Rikhie J, Sampath S. Reversible Electrochemistry of Cytochrome c on Recompressed, Binderless Exfoliated Graphite Electrodes. ELECTROANAL 2005. [DOI: 10.1002/elan.200403149] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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28
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Santoni E, Scatragli S, Sinibaldi F, Fiorucci L, Santucci R, Smulevich G. A model for the misfolded bis-His intermediate of cytochrome c: the 1-56 N-fragment. J Inorg Biochem 2005; 98:1067-77. [PMID: 15149817 DOI: 10.1016/j.jinorgbio.2004.02.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 02/09/2004] [Accepted: 02/19/2004] [Indexed: 10/26/2022]
Abstract
We have characterized the ferric and ferrous forms of the heme-containing (1-56 residues) N-fragment of horse heart cytochrome c (cyt c) at different pH values and low ionic strength by UV-visible absorption and resonance Raman (RR) scattering. The results are compared with native cyt c in the same experimental conditions as this may provide a deeper insight into the cyt c unfolding-folding process. Folding of cyt c leads to a state having the heme iron coordinated to a histidine (His18) and a methionine (Met80) as axial ligands. At neutral pH the N-fragment (which lacks Met80) shows absorption and RR spectra that are consistent with the presence of a bis-His low spin heme, like several non-native forms of the parental protein. In particular, the optical spectra are identical to those of cyt c in the presence of a high concentration of denaturants; this renders the N-fragment a suitable model to study the heme pocket microenvironment of the misfolded (His-His) intermediate formed during folding of cyt c. Acid pH affects the ligation state in both cyt c and the N-fragment. Data obtained as a function of pH allow a correlation between the structural properties in the heme pocket of the N-fragment and those of non-native forms of cyt c. The results underline that the (57-104 residues) segment under native-like conditions imparts structural stability to the protein by impeding solvent access into the heme pocket.
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Affiliation(s)
- Elisa Santoni
- Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Florence, Italy
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29
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Takayama SIJ, Mikami SI, Terui N, Mita H, Hasegawa J, Sambongi Y, Yamamoto Y. Control of the Redox Potential of Pseudomonas aeruginosa Cytochrome c551 through the Fe−Met Coordination Bond Strength and pKa of a Buried Heme Propionic Acid Side Chain. Biochemistry 2005; 44:5488-94. [PMID: 15807542 DOI: 10.1021/bi047498s] [Citation(s) in RCA: 23] [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
Pseudomonas aeruginosa cytochrome c(551) and a series of its mutants exhibiting various thermostabilities have been studied by paramagnetic (1)H NMR and cyclic voltammetry in an effort to elucidate the molecular mechanisms responsible for control of the redox potentials (E degrees ') of the proteins. The study revealed that the E degrees ' value of the protein is regulated by two molecular mechanisms operating independently of each other. One is based on the Fe-Met coordination bond strength in the protein, which is determined by the amino acid side chain packing in the protein, and the other on the pK(a) of the heme 17-propionic acid side chain, which is affected by the electrostatic environment. The former mechanism alters the magnitude of the E degrees ' value throughout the entire pH range, and the latter regulates the pK values reflected by the pH profile of the E degrees ' value. These findings provide novel insights into functional regulation of the protein, which could be utilized for tuning the E degrees ' value of the protein by means of protein engineering.
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30
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Uchiyama S, Ohshima A, Nakamura S, Hasegawa J, Terui N, Takayama SIJ, Yamamoto Y, Sambongi Y, Kobayashi Y. Complete Thermal-Unfolding Profiles of Oxidized and Reduced Cytochromes c. J Am Chem Soc 2004; 126:14684-5. [PMID: 15535669 DOI: 10.1021/ja046667t] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The complete thermal-unfolding profiles of both oxidized and reduced forms of cytochrome c551 (PA) from mesophilic Pseudomonas aeruginosa and cytochrome c552 (HT) from thermophilic Hydrogenobacter thermophilus were obtained by the newly developed pressure-proof cell compartment installed in a circular dichroic spectrometer, which facilitates protein thermal-unfolding experiments up to 180 degrees C. The thermodynamic cycle, which relates protein stability and redox function, indicated that the redox potentials of PA and HT in the native state are regulated by the stability of the oxidized proteins rather than by that of the reduced ones.
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Affiliation(s)
- Susumu Uchiyama
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871, Japan
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31
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Caroppi P, Sinibaldi F, Santoni E, Howes BD, Fiorucci L, Ferri T, Ascoli F, Smulevich G, Santucci R. The 40s ?-loop plays a critical role in the stability and the alkaline conformational transition of cytochrome c. J Biol Inorg Chem 2004; 9:997-1006. [PMID: 15503233 DOI: 10.1007/s00775-004-0601-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 09/14/2004] [Indexed: 10/26/2022]
Abstract
The structural and redox properties of a non-covalent complex reconstituted upon mixing two non-contiguous fragments of horse cytochrome c, the residues 1-38 heme-containing N-fragment with the residues 57-104 C-fragment, have been investigated. With respect to native cyt c, the complex lacks a segment of 18 residues, corresponding, in the native protein, to an omega (Omega)-loop region. The fragment complex shows compact structure, native-like alpha-helix content but a less rigid atomic packing and reduced stability with respect to the native protein. Structural heterogeneity is observed at pH 7.0, involving formation of an axially misligated low-spin species and consequent partial displacement of Met80 from the sixth coordination position of the heme-iron. Spectroscopic data suggest that a lysine (located in the Met80-containing loop, namely Lys72, Lys73, or Lys79) replaces the methionine residue. The residues 1-38/57-104 fragment complex shows an unusual biphasic alkaline titration characterized by a low (p K(a1)=6.72) and a high p K(a)-associated state transition (p K(a2)=8.56); this behavior differs from that of native cyt c, which shows a monophasic alkaline transition (p K(a)=8.9). The data indicate that the 40s Omega-loop plays an important role in the stability of cyt c and in ensuring a correct alkaline conformational transition of the protein.
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Affiliation(s)
- Paola Caroppi
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Roma Tor Vergata, via Montpellier 1, 00133, Rome, Italy
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32
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Sun Y, Liu X, Fan C, Zhang W, Li G. Electrochemical investigation of the chloride effect on hemoglobin. Bioelectrochemistry 2004; 64:23-7. [PMID: 15219242 DOI: 10.1016/j.bioelechem.2004.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2003] [Revised: 01/05/2004] [Accepted: 01/14/2004] [Indexed: 10/26/2022]
Abstract
Direct electron transfer between hemoglobin and gold electrode is achieved at both a bare and a 4, 4'-bipyridine-modified gold electrode in the presence of chloride ions. The addition of chloride to hemoglobin solution also increases the reversibility of the direct electrochemistry and shifts the formal potential of hemoglobin to the negative direction. While the existence of chloride does not significantly change the tertiary structure of the protein, it might induce a slight variation of the structure, which is beneficial to the electrochemical response. It is suggested that the chloride binding to hemoglobin is a combination of specific and unspecific bindings.
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Affiliation(s)
- Yuting Sun
- Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, PR China
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33
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Suruga K, Nagasawa N, Yamada S, Satoh T, Kawachi R, Nishio T, Kume T, Oku T. Radiation-induced enhancement of nitrite reducing activity of cytochrome c. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2003; 51:6835-6843. [PMID: 14582983 DOI: 10.1021/jf0345651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Commercial cytochrome c (Cyt c) was irradiated with Co-60 gamma-rays in the dose range of up to 3.0 kGy to investigate the enhancement of the nitrite reducing activity of Cyt c. The optimum irradiation dose to induce nitrite reducing activity for 30 muM Cyt c solution was 1.0 kGy under an O(2) atmosphere. The nitrite reducing activity of Cyt c irradiated at this dose was approximately 45-fold that of unirradiated Cyt c and ca. 1.2-fold that of nitrite reductase. The irradiation treatment resulted in unfolding of the peptide chain, exposure of the heme group, oxidation of methionine to methionine sulfoxide, dissociation of the sixth ligand (Met), and occurrence of autoxidation in Cyt c. Sepharose-immobilized irradiated Cyt c had a similar activity to that in solution. The resin retained the activity after five uses even after 1 year of storage. The irradiated Cyt c will be able to be used as a substitute for nitrite reductase.
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Affiliation(s)
- Kohei Suruga
- Department of Biological Chemistry, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-8510, Japan
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34
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Boussaad S, Tao N. Kinetics of electron transfer-induced conformational changes in cytochrome c immobilized on electrodes studied with surface plasmon resonance. J Electroanal Chem (Lausanne) 2003. [DOI: 10.1016/s0022-0728(03)00197-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Wackerbarth H, Hildebrandt P. Redox and conformational equilibria and dynamics of cytochrome c at high electric fields. Chemphyschem 2003; 4:714-24. [PMID: 12901303 DOI: 10.1002/cphc.200200618] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cytochrome c (Cyt-c) adsorbed in the electrical double layer of the Ag electrode/electrolyte interface has been studied by stationary and time-resolved surface-enhanced resonance Raman spectroscopy to analyse the effect of strong electric fields on structure and reaction equilibria and dynamics of the protein. In the potential range between +0.1 and -0.55 V (versus saturated calomel electrode), the adsorbed Cyt-c forms a potential-dependent reversible equilibrium between the native state B1 and a conformational state B2. The redox potentials of the bis-histidine-coordinated six-coordinated low-spin and five-coordinated high-spin substates of B2 were determined to be -0.425 and -0.385 V, respectively, whereas the additional six-coordinated aquo-histidine-coordinated high-spin substate was found to be redox-inactive. The redox potential for the conformational state B1 was found to be the same as in solution in agreement with the structural identity of the adsorbed B1 and the native Cyt-c. For all three redox-active species, the formal heterogeneous electron transfer rate constants are small and of the same order of magnitude (3-13 s-1), which implies that the rate-limiting step is largely independent of the redox-site structure. These findings, as well as the slow and potential-dependent transitions between the various conformational (sub-)states, can be rationalized in terms of an electric field-induced increase of the activation energy for proton-transfer steps linked to protein structural reorganisation. Further increasing the electric field strength by shifting the electrode potential above +0.1 V leads to irreversible structural changes that are attributed to an unfolding of the polypeptide chain.
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Affiliation(s)
- Hainer Wackerbarth
- Danmarks Tekniske Universitet Biouorganisk Kemi Bygning 207, 2800 Lyngby, Denmark
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36
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Moza B, Qureshi SH, Ahmad F. Equilibrium studies of the effect of difference in sequence homology on the mechanism of denaturation of bovine and horse cytochromes-c. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1646:49-56. [PMID: 12637011 DOI: 10.1016/s1570-9639(02)00548-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have carried out equilibrium studies of the effect of the amino acid residue difference in the primary structure of bovine cytochrome-c (b-cyt-c) and horse cyt-c (h-cyt-c) on the mechanism of their folding <--> unfolding processes at pH 6.0 and 25 degrees C. It has been observed that guanidinium chloride (GdmCl)-induced denaturation of b-cyt-c follows a two-state mechanism and that of h-cyt-c is not a two-state process. This conclusion is reached from the coincidence and non-coincidence of GdmCl-induced transition curves of bovine and horse proteins, respectively, monitored by measurements of absorbance at 405, 530 and 695 nm and circular dichroism (CD) at 222, 416 and 405 nm. These measurements on h-cyt-c in the presence of GdmCl in the concentration range 0.75-2.0 M also suggest that the protein retains all the native far-UV CD but has slightly perturbed tertiary interaction. The intermediate in the presence of these low denaturant concentrations does not have the structural characteristics of a molten globule as judged by the 8-Anilino-1-napthalene sulfonic acid (ANS) binding and near-UV CD experiments. We have also carried out thermal denaturation studies of bovine and horse cyts-c in the presence of GdmCl monitored by absorbance at 405 nm and far-UV CD at 222 nm. The heat-induced denaturation measurements in the presence of the denaturant show (1) that denaturation of b-cyt-c is a two-state process and that of h-cyt-c does not follow a two-state mechanism, and (2) that the enthalpy change on denaturation of both proteins strongly depends on GdmCl concentration.
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Affiliation(s)
- Beenu Moza
- Department of Biosciences, Jamia Millia Islamia, Jamia Nagar, New Delhi-110 025, India
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37
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Qureshi SH, Moza B, Yadav S, Ahmad F. Conformational and thermodynamic characterization of the molten globule state occurring during unfolding of cytochromes-c by weak salt denaturants. Biochemistry 2003; 42:1684-95. [PMID: 12578383 DOI: 10.1021/bi0271042] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The denaturation of bovine and horse cytochromes-c by weak salt denaturants (LiCl and CaCl(2)) was measured at 25 degrees C by observing changes in molar absorbance at 400 nm (Delta epsilon(400)) and circular dichroism (CD) at 222 and 409 nm. Measurements of Delta epsilon(400) and mean residue ellipticity at 409 nm ([theta](409)) gave a biphasic transition for both modes of denaturation of cytochromes-c. It has been observed that the first denaturation phase, N (native) conformation <--> X (intermediate) conformation and the second denaturation phase, X conformation <--> D (denatured) conformation are reversible. Conformational characterization of the X state by the far-UV CD, 8-anilino-1-naphthalene sulfonic acid (ANS) binding, and intrinsic viscosity measurements led us to conclude that the X state is a molten globule state. Analysis of denaturation transition curves for the stability of different states in terms of Gibbs energy change at pH 6.0 and 25 degrees C led us to conclude that the N state is more stable than the X state by 9.55 +/- 0.32 kcal mol(-1), whereas the X state is more stable than the D state by only 1.40 +/- 0.25 kcal mol(-1). We have also studied the effect of temperature on the equilibria, N conformation <--> X conformation and X conformation <--> D conformation in the presence of different denaturant concentrations using two different optical probes, namely, [theta](222) and Delta epsilon(400). These measurements yielded T(m), (midpoint of denaturation) and Delta H(m) (enthalpy change) at T(m) as a function of denaturant concentration. A plot of Delta H(m) versus corresponding T(m) was used to determine the constant-pressure heat capacity change, Delta C(p) (= ( partial differential Delta H(m)/ partial differential T(m))(p)). Values of Delta C(p) for N conformation <--> X conformation and X conformation <--> D conformation is 0.92 +/- 0.02 kcal mol(-1) K(-1) and 0.41 +/- 0.01 kcal mol(-1) K(-1), respectively. These measurements suggested that about 30% of the hydrophobic groups in the molten globule state are not accessible to the water.
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Affiliation(s)
- Shabir H Qureshi
- Department of Biosciences, Jamia Millia Islamia, Jamia Nagar, New Delhi - 110 025, India
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Moosavi-Movahedi AA, Chamani J, Ghourchian H, Shafiey H, Sorenson CM, Sheibani N. Electrochemical evidence for the molten globule states of cytochrome c induced by N-alkyl sulfates at low concentrations. JOURNAL OF PROTEIN CHEMISTRY 2003; 22:23-30. [PMID: 12739895 DOI: 10.1023/a:1023011609931] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The molten globule state (MG) of cytochrome c is the major intermediate of protein folding. The formation of MG state of cytochrome c is induced by n-alkyl sulfates such as sodium octyl sulfate (SOS), sodium dodecyl sulfate (SDS), and sodium tetradecyl sulfate (STS). The folding state of cytochrome c was monitored using circular dichroism (CD), isothermal titration calorimetry (ITC) and partial specific volumes. To explore a new approach for characterizing the MG conformation, cyclic voltametric studies of n-alkyl sulfates induced transition at acidic pH of cytochrome c (unfolded state, U) was carried out. Here, we have used a cystein-modified gold electrode, which is effective for direct rapid electron transfer to cytochrome c even in acid solutions, to directly observe electrochemistry in native (N) cytochrome c. Our results show that the extent of electron transfer is increased for U --> MG, and also the easiness of electron transferring occurred from MG --> N transition. Thus we demonstrate that the MG state of cytochrome c, induced by n-alkyl sulfates as salts with hydrophobic chains (hydrophobic salts), with different compactness reaches to near identical amount of electron transferring as N state.
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39
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Fan C, Gillespie B, Wang G, Heeger AJ, Plaxco KW. Spectroscopy and Electrochemistry of the Covalent Pyridine-Cytochrome c Complex and a Pyridine-Induced, “Alkaline-like” Conformation. J Phys Chem B 2002. [DOI: 10.1021/jp0261307] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chunhai Fan
- Institute for Polymers and Organic Solids, and Department of Chemistry and Biochemistry and Interdepartmental Program in Biomolecular Science and Engineering, and Department of Physics and Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Blake Gillespie
- Institute for Polymers and Organic Solids, and Department of Chemistry and Biochemistry and Interdepartmental Program in Biomolecular Science and Engineering, and Department of Physics and Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Guangming Wang
- Institute for Polymers and Organic Solids, and Department of Chemistry and Biochemistry and Interdepartmental Program in Biomolecular Science and Engineering, and Department of Physics and Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Alan J. Heeger
- Institute for Polymers and Organic Solids, and Department of Chemistry and Biochemistry and Interdepartmental Program in Biomolecular Science and Engineering, and Department of Physics and Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Kevin W. Plaxco
- Institute for Polymers and Organic Solids, and Department of Chemistry and Biochemistry and Interdepartmental Program in Biomolecular Science and Engineering, and Department of Physics and Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106
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Bongiovanni C, Sinibaldi F, Ferri T, Santucci R. Glycerol-induced formation of the molten globule from acid-denatured cytochrome c: implication for hierarchical folding. JOURNAL OF PROTEIN CHEMISTRY 2002; 21:35-41. [PMID: 11902665 DOI: 10.1023/a:1014179031881] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
At high concentration (98% or higher, v/v), glycerol induces collapse of acid-denatured cytochrome c into a compact state, the G(U) state, showing a molten globule character. The G(U) state possesses a nativelike alpha-helix structure but a tertiary conformation less packed with respect to the native state. The spectroscopic properties of the G(U) state closely resemble those of the molten globule stabilized by the organic solvent from the native protein (called the G(N) state), indicating that glycerol can stabilize the molten globule of cytochrome c either from the native or the acid-denatured protein. The G(U) and the G(N) states show spectroscopic (and, thus, structural) properties and stabilities comparable to those of molten globules stabilized by different effectors, despite the fact that the mechanisms involved in the molten globule formation may significantly differ. This implies in cytochrome c a hierarchy for the rupture (native-to-molten globule) or the formation (unfolded-to-molten globule) of intramolecular interactions leading to the stabilization of the molten globule state of the protein, independently from the effector responsible for the structural transition, in accord with the sequential model proposed by Englander and collaborators.
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Affiliation(s)
- Cristiana Bongiovanni
- Università di Roma Tor Vergata, Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Italy
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41
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Abstract
Equilibrium and kinetic folding studies of horse cytochrome c in the reduced state have been carried out under strictly anaerobic conditions at neutral pH, 10 degrees C, in the entire range of aqueous solubility of guanidinium hydrochloride (GdnHCl). Equilibrium unfolding transitions observed by Soret heme absorbance, excitation energy transfer from the lone tryptophan residue to the ferrous heme, and far-UV circular dichroism (CD) are all biphasic and superimposable, implying no accumulation of structural intermediates. The thermodynamic parameters obtained by two-state analysis of these transitions yielded DeltaG(H2O)=18.8(+/-1.45) kcal mol(-1), and C(m)=5.1(+/-0.15) M GdnHCl, indicating unusual stability of reduced cytochrome c. These results have been used in conjunction with the redox potential of native cytochrome c and the known stability of oxidized cytochrome c to estimate a value of -164 mV as the redox potential of the unfolded protein. Stopped-flow kinetics of folding and unfolding have been recorded by Soret heme absorbance, and tryptophan fluorescence as observables. The refolding kinetics are monophasic in the transition region, but become biphasic as moderate to strongly native-like conditions are approached. There also is a burst folding reaction unobservable in the stopped-flow time window. Analyses of the two observable rates and their amplitudes indicate that the faster of the two rates corresponds to apparent two-state folding (U<-->N) of 80-90 % of unfolded molecules with a time constant in the range 190-550 micros estimated by linear extrapolation and model calculations. The remaining 10-20 % of the population folds to an off-pathway intermediate, I, which is required to unfold first to the initial unfolded state, U, in order to refold correctly to the native state, N (I<-->U<-->N). The slower of the two observable rates, which has a positive slope in the linear functional dependence on the denaturant concentration indicating that an unfolding process under native-like conditions indeed exists, originates from the unfolding of I to U, which rate-limits the overall folding of these 10-20 % of molecules. Both fast and slow rates are independent of protein concentration and pH of the refolding milieu, suggesting that the off-pathway intermediate is not a protein aggregate or trapped by heme misligation. The nature or type of unfolded-state heme ligation does not interfere with refolding. Equilibrium pH titration of the unfolded state yielded coupled ionization of the two non-native histidine ligands, H26 and H33, with a pK(a) value of 5.85. A substantial fraction of the unfolded population persists as the six-coordinate form even at low pH, suggesting ligation of the two methionine residues, M65 and M80. These results have been used along with the known ligand-binding properties of unfolded cytochrome c to propose a model for heme ligation dynamics. In contrast to refolding kinetics, the unfolding kinetics of reduced cytochrome c recorded by observation of Soret absorbance and tryptophan fluorescence are all slow, simple, and single-exponential. In the presence of 6.8 M GdnHCl, the unfolding time constant is approximately 300(+/-125) ms. There is no burst unfolding reaction. Simulations of the observed folding-unfolding kinetics by numerical solutions of the rate equations corresponding to the three-state I<-->U<-->N scheme have yielded the microscopic rate constants.
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Affiliation(s)
- A K Bhuyan
- School of Chemistry, University of Hyderabad, Hyderabad, 500046, India.
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42
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Sinibaldi F, Fiorucci L, Mei G, Ferri T, Desideri A, Ascoli F, Santucci R. Cytochrome c reconstituted from two peptide fragments displays native-like redox properties. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:4537-43. [PMID: 11502215 DOI: 10.1046/j.1432-1327.2001.02373.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recombination of two fragments of horse cytochrome c (the heme-containing N-fragment, residues 1-56, and the C-fragment, residues 57-104), which are substantially unstructured at neutral pH, gives rise to a 1:1 fragment complex with a compact conformation, in which the alpha helical structure and the native Met80-Fe(III) axial bond are recovered. With respect to the native protein, the ferric complex shows a less rigid atomic packing and a decreased stability [Delta(DeltaG(o))D = 14.7 kJ.mol(-1)], ascribed to perturbations involving the Trp59 microenvironment and, to a lower extent, the heme pocket region. The redox potential, E1/2 = 234 +/- 5 mV vs. normal hydrogen electrode at 25 degrees C, is close to that of the intact protein, consistent with recovery of the native Met80-heme Fe(III) axial bond. Furthermore, the fragment complex shows reactivity similar to intact cytochrome c, in the reaction with cytochrome c oxidase. We conclude that the absence in the complex of some native cross-links and interlocked packing important for protein rigidity and stability is not as relevant for maintaining the native redox properties of the protein, provided that some structural requirements (i.e. recovering of the native-like alpha helical structure) are fulfilled and coordination of Met80 to the heme-iron is restored.
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Affiliation(s)
- F Sinibaldi
- Department of Experimental Medicine and Biochemical Sciences, University of Rome 'Tor Vergata', Italy
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43
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Fan C, Wang H, Sun S, Zhu D, Wagner G, Li G. Electron-transfer reactivity and enzymatic activity of hemoglobin in a SP Sephadex membrane. Anal Chem 2001; 73:2850-4. [PMID: 11467526 DOI: 10.1021/ac001397s] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hemoglobin can exhibit a direct electron-transfer reaction after being entrapped in a SP Sephadex membrane. A pair of stable and well-defined redox waves are obtained at a hemoglobin-SP sephadex modified pyrolytic graphite electrode. The anodic and cathodic peak potentials are located at -0.244 and -0.336 V (vs SCE), respectively. On the other hand, the peroxidase activity of the protein in the membrane is also greatly enhanced. The apparent Michaelis-Menten constant is calculated to be 1.9 mM, which shows a large catalytic activity of hemoglobin in the SP Sephadex membrane toward hydrogen peroxide (H2O2). According to the direct electron-transfer property and enhanced peroxidase activity of Hb in the membrane, a Hb/SP Sephadex membrane-based H2O2 biosensor is prepared, with a linear range approximately 5.0 x 10(-6) to 1.6 x 10(-4) mol/L.
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Affiliation(s)
- C Fan
- Department of Biochemistry and National Laboratory of Pharmaceutical Biotechnology, Nanjing University, PR China
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44
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Fedurco M. Redox reactions of heme-containing metalloproteins: dynamic effects of self-assembled monolayers on thermodynamics and kinetics of cytochrome c electron-transfer reactions. Coord Chem Rev 2000. [DOI: 10.1016/s0010-8545(00)00292-7] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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45
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Santucci R, Bongiovanni C, Mei G, Ferri T, Polizio F, Desideri A. Anion size modulates the structure of the A state of cytochrome c. Biochemistry 2000; 39:12632-8. [PMID: 11027143 DOI: 10.1021/bi000516v] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Several studies have shown that anions induce collapse of acid-denatured cytochrome c into the compact A state having the properties of the molten globule and that the anion charge is the main determinant for the A state stabilization. The results here reported show that the anion size plays a role in determining the overall structure of the A state. In particular, small anions induce formation of an A state in which the native Met80-Fe(III) axial bond is recovered and the nativelike redox properties restored. On the other hand, the A state stabilized by large anions shows a histidine (His26 or His33) as the sixth ligand of the heme-iron, a very weak interaction between Trp59 and the heme propionate, and lacks nativelike redox properties. The two anion-stabilized states show similar stability, indicating that (i) the hydrophobic core (which is equally stabilized by all the anions investigated, independently of their size) is the region that mainly contributes to the macromolecule stabilization, and (ii) the flexible loops are responsible for the spectroscopic (and, thus, structural) and redox differences observed.
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Affiliation(s)
- R Santucci
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche; Università di Roma "Tor Vergata", V. Tor Vergata 135, 00133 Roma, Italy.
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46
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Santucci R, Fiorucci L, Sinibaldi F, Polizio F, Desideri A, Ascoli F. The heme-containing N-fragment (residues 1-56) of cytochrome c is a bis-histidine functional system. Arch Biochem Biophys 2000; 379:331-6. [PMID: 10898952 DOI: 10.1006/abbi.2000.1885] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structural and redox properties of a heme-containing fragment (1-56 residues) of cytochrome c have been investigated by spectroscopic (circular dichroism, electronic absorption, and EPR) and voltammetric techniques. The results indicate that the N-fragment lacks ordered secondary structure and has two histidines axially bound to the heme-iron (the native His18 and a misligated His26 or His33). Despite the absence of ordered secondary structure, the peptide chain shields the heme group from solvent, as shown by (i) the pK(a) of protonation of the nonnative histidine ligand (5.18 +/- 0.05), lower than that of the bis-histidine guanidine-unfolded cytochrome c (5.58 +/- 0.05), and (ii) the redox potential, E(o) = 0 +/- 5 mV versus NHE, close to that of bis-histidine cytochrome c mutants but less negative than that of bis-histidine complexes of microperoxidase with short peptides. The electroactive N-fragment may be taken as a "minichrome c" model, with interesting potential for application to biosensor technology; further, the system provides useful information for a deeper understanding of cytochrome c folding and structural/functional organization.
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Affiliation(s)
- R Santucci
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Roma "Tor Vergata,", Rome, Italy.
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Thomas YG, Goldbeck RA, Kliger DS. Characterization of equilibrium intermediates in denaturant-induced unfolding of ferrous and ferric cytochromes c using magnetic circular dichroism, circular dichroism, and optical absorption spectroscopies. Biopolymers 2000; 57:29-36. [PMID: 10679637 DOI: 10.1002/(sici)1097-0282(2000)57:1<29::aid-bip5>3.0.co;2-v] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein unfolding during guanidine HCl denaturant titration of the reduced and oxidized forms of cytochrome c is monitored with magnetic circular dichroism (MCD), natural CD, and absorption of the heme bands and far-UV CD of the amide bands. Direct MCD spectral evidence is presented for bis-histidinyl heme ligation in the unfolded states of both the reduced and oxidized protein. For both redox states, the unfolding midpoints measured with MCD, which is an indicator of tertiary structure, are significantly lower than those measured with far-UV CD, an indicator of secondary structure. The disparate titration curves are interpreted in terms of a compound mechanism for denaturant-induced folding and unfolding involving a molten globulelike intermediate state (MG) with near-native secondary structure and nonnative tertiary structure and heme ligation. A comparison of the dependence of the free energy of formation of the MG intermediate on the redox state with the known contributions from heme ligation and solvation suggests that the heme is significantly more accessible to solvent in the MG intermediate than it is in the native state.
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Affiliation(s)
- Y G Thomas
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
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48
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Santucci R, Polizio F, Desideri A. Formation of a molten-globule-like state of cytochrome c induced by high concentrations of glycerol. Biochimie 1999; 81:745-51. [PMID: 10492021 DOI: 10.1016/s0300-9084(99)80132-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effect of glycerol on the structure of cytochrome c was investigated by circular dichroism, absorbance and EPR spectroscopy. The results obtained show that an increasing concentration of the organic solvent (70-99.2%, v/v) in aqueous-polyalcohol mixtures converts native cytochrome c into a new, low spin form through a fully reversible, two-state transition. The glycerol-stabilized form (that we call here the G state) retains native-like amounts of alpha-helix structure while rigid tertiary structure and native Fe(III)-Met(80) axial bond are lost. Analysis of data suggests a molten globule character of the G state; support to this view is afforded by the striking similarities between the spectroscopic (and, thus, structural) properties of the G state with those of the acidic molten globule of the protein (A state).
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Affiliation(s)
- R Santucci
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Universitá di Roma Tor Vergata, Rome, Italy
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49
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Liu C, Bo A, Cheng G, Lin X, Dong S. Characterization of the structural and functional changes of hemoglobin in dimethyl sulfoxide by spectroscopic techniques. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1385:53-60. [PMID: 9630511 DOI: 10.1016/s0167-4838(98)00044-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Circular dichroism (CD), fourier transform infrared (FTIR), and fluorescence spectroscopy were used to explore the effect of dimethyl sulfoxide (DMSO) on the structure and function of hemoglobin (Hb). The native tertiary structure was disrupted completely when the concentration of DMSO reached 50% (v/v), which was determined by loss of the characteristic Soret CD spectrum. Loss of the native tertiary structure could be mainly caused by breaking the hydrogen bonds, between the heme propionate groups and nearby surface amino acid residues, and by disorganizing the hydrophobic interior of this protein. Upon exposure of Hb to 52% DMSO for ca. 12 h in a D2O medium no significant change in 1652 cm-1 band of the FTIR spectrum was produced, which demonstrated that alpha-helical structure predominated. When the concentration of DMSO increased to 57%: (1) the band at 1652 cm-1 disappeared with the appearance of two new bands located at 1661 and 1648 cm-1; (2) another new band at 1623 cm-1 was attributed to the formation of intermolecular beta-sheet or aggregation, which was the direct consequence of breaking of the polypeptide chain by the competition of S&z.dbnd6;O groups in DMSO with C&z.dbnd6;O groups in amide bonds. Further increasing the DMSO concentration to 80%, the intensity at 1623 cm-1 increased, and the bands at 1684, 1661 and 1648 cm-1 shifted to 1688, 1664 and 1644 cm-1, respectively. These changes showed that the native secondary structure of Hb was lost and led to further aggregation and increase of the content of 'free' amide C&z.dbnd6;O groups. In pure DMSO solvent, the major band at 1664 cm-1 indicated that almost all of both the intermolecular beta-sheet and any residual secondary structure were completely disrupted. The red shift of the fluorescence emission maxima showed that the tryptophan residues were exposed to a greater hydrophilic environment as the DMSO content increased. CO-binding experiment suggested that the biological function of Hb was disrupted seriously even if the content of DMSO was 20%.
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Affiliation(s)
- C Liu
- Laboratory of Electroanalytical Chemistry and National Analysis and Research Center of Electrochemistry and Spectroscopy, Changchun, Jilin 130022, China
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50
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Affiliation(s)
- James L. Anderson
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - Louis A. Coury
- Bioanalytical Systems Inc., 2701 Kent Avenue, West Lafayette, Indiana 47906-1382
| | - Johna Leddy
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
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