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Costa Pereira C, Durães C, Coelho R, Grácio D, Silva M, Peixoto A, Lago P, Pereira M, Catarino T, Pinho S, Teixeira JP, Macedo G, Annese V, Magro F. Association between Polymorphisms in Antioxidant Genes and Inflammatory Bowel Disease. PLoS One 2017; 12:e0169102. [PMID: 28052094 PMCID: PMC5215755 DOI: 10.1371/journal.pone.0169102] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/12/2016] [Indexed: 12/14/2022] Open
Abstract
Inflammation is the driving force in inflammatory bowel disease (IBD) and its link to oxidative stress and carcinogenesis has long been accepted. The antioxidant system of the intestinal mucosa in IBD is compromised resulting in increased oxidative injury. This defective antioxidant system may be the result of genetic variants in antioxidant genes, which can represent susceptibility factors for IBD, namely Crohn's disease (CD) and ulcerative colitis (UC). Single nucleotide polymorphisms (SNPs) in the antioxidant genes SOD2 (rs4880) and GPX1 (rs1050450) were genotyped in a Portuguese population comprising 436 Crohn's disease and 367 ulcerative colitis patients, and 434 healthy controls. We found that the AA genotype in GPX1 is associated with ulcerative colitis (OR = 1.93, adjusted P-value = 0.037). Moreover, we found nominal significant associations between SOD2 and Crohn's disease susceptibility and disease subphenotypes but these did not withstand the correction for multiple testing. These findings indicate a possible link between disease phenotypes and antioxidant genes. These results suggest a potential role for antioxidant genes in IBD pathogenesis and should be considered in future association studies.
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Affiliation(s)
- Cristiana Costa Pereira
- Department of Environmental Health, National Institute of Health Dr. Ricardo Jorge, Oporto, Portugal
- MedInUP – Centre for Drug Discovery and Innovative Medicines, University of Porto, Oporto, Portugal
- EPIUnit – Institute of Public Health, University of Porto, Oporto, Portugal
| | - Cecília Durães
- Ipatimup – Institute of Molecular Pathology and Immunology of the University of Porto, Oporto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Oporto, Portugal
| | - Rosa Coelho
- Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Oporto, Portugal
| | - Daniela Grácio
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Oporto, Portugal
| | - Marco Silva
- Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Oporto, Portugal
| | - Armando Peixoto
- Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Oporto, Portugal
| | - Paula Lago
- Department of Gastroenterology, HSA – Centro Hospitalar do Porto, Oporto, Portugal
| | - Márcia Pereira
- Ipatimup – Institute of Molecular Pathology and Immunology of the University of Porto, Oporto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Oporto, Portugal
- Institute for the Biomedical Sciences Abel Salazar, University of Porto, Oporto, Portugal
| | - Telmo Catarino
- Ipatimup – Institute of Molecular Pathology and Immunology of the University of Porto, Oporto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Oporto, Portugal
| | - Salomé Pinho
- Ipatimup – Institute of Molecular Pathology and Immunology of the University of Porto, Oporto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Oporto, Portugal
| | - João Paulo Teixeira
- Department of Environmental Health, National Institute of Health Dr. Ricardo Jorge, Oporto, Portugal
- EPIUnit – Institute of Public Health, University of Porto, Oporto, Portugal
| | - Guilherme Macedo
- Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Oporto, Portugal
| | - Vito Annese
- Emergency Department, Gastroenterology Unit, AOU Careggi, Florence, Italy
| | - Fernando Magro
- MedInUP – Centre for Drug Discovery and Innovative Medicines, University of Porto, Oporto, Portugal
- Department of Gastroenterology, Faculty of Medicine, Centro Hospitalar São João, Oporto, Portugal
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Oporto, Portugal
- * E-mail:
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Mendes S, Catarino T, Silveira C, Todorovic S, Martins LO. The catalytic mechanism of A-type dye-decolourising peroxidase BsDyP: neither aspartate nor arginine is individually essential for peroxidase activity. Catal Sci Technol 2015. [DOI: 10.1039/c5cy00478k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BsDyP from Bacillus subtilis belongs to the new dye-decolourising peroxidase (DyP) family. Here, we use transient kinetics to provide details on the catalytic cycle of BsDyP.
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Affiliation(s)
- S. Mendes
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - T. Catarino
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
- Departamento de Química
- Faculdade de Ciências e Tecnologia
| | - C. Silveira
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - S. Todorovic
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - L. O. Martins
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
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Vinagre J, Pinto V, Celestino R, Reis M, Pópulo H, Boaventura P, Melo M, Catarino T, Lima J, Lopes JM, Máximo V, Sobrinho-Simões M, Soares P. Telomerase promoter mutations in cancer: an emerging molecular biomarker? Virchows Arch 2014; 465:119-33. [DOI: 10.1007/s00428-014-1608-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/19/2014] [Accepted: 06/16/2014] [Indexed: 12/16/2022]
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Martins RG, Nunes JB, Máximo V, Soares P, Peixoto J, Catarino T, Rito T, Soares P, Pereira L, Sobrinho-Simões M, Santos AP, Couto J, Henrique R, Matos-Loureiro J, Dias P, Torres I, Lima J. A founder SDHB mutation in Portuguese paraganglioma patients. Endocr Relat Cancer 2013; 20:L23-6. [PMID: 24092654 DOI: 10.1530/erc-12-0399] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Raquel G Martins
- IPATIMUP (Institute of Pathology and Molecular Immunology of the University of Porto), Rua Dr Roberto Frias s/n, 4200-465, Porto, Portugal Medical Faculty of the University of Porto, Porto, Portugal Department of Endocrinology, Portuguese Oncology Institute, Porto, Portugal Department of Pathology, Hospital S. João, Porto, Portugal Department of Pathology, Portuguese Oncology Institute, Porto, Portugal
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Lima J, Reis RM, Catarino T, Peixoto J, Vinagre J, Batista R, Castro L, Pardal F, Sobrinho-Simoes M, Maximo V, Soares P. Abstract C118: TERT promoter mutations in human gliomas. Mol Cancer Ther 2013. [DOI: 10.1158/1535-7163.targ-13-c118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Reactivation of telomerase has been implicated in human tumorigenesis, but the underlying mechanisms remain poorly understood. Recently, two mutations (-124G>A and -146G>A) in the promoter region of the telomerase catalytic subunit (TERT) were found in a significant proportion of human tumors, including gliomas, thyroid carcinomas, bladder carcinomas and melanomas. These mutations resulted in increased expression of telomerase, both in vitro and in vivo. In order to further characterize the prevalence of TERT mutations in human tumors, we screened a cohort of 273 human gliomas and found an overall TERT mutation frequency of 50%. TERT mutations were most commonly found in high grade tumors such as glioblastoma multiforme (GBM) and gliosarcoma (65% and 89%, respectively), whereas low grade tumors such as pilocytic astrocytoma and diffuse astrocytoma showed a low frequency of TERT mutations (6% and 16%, respectively). Oligodendrogliomas (grade II) and anaplastic oligodendrogliomas (grade III) also harbored a high frequency of TERT mutations (44% and 52%, respectively). In GBM patients, the presence of TERT mutations was significantly associated with a higher mean age at diagnosis (p<0.0001) and worse survival (p=0.006). Our results show that TERT promoter mutations are frequent in human GBM and oligodendrogliomas and are associated with worse survival in GBM patients.
Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C118.
Citation Format: Jorge Lima, Rui M. Reis, Telmo Catarino, Joana Peixoto, Joao Vinagre, Rui Batista, Ligia Castro, Fernando Pardal, Manuel Sobrinho-Simoes, Valdemar Maximo, Paula Soares. TERT promoter mutations in human gliomas. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C118.
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Affiliation(s)
| | - Rui M. Reis
- 2Life and Health Sciences Research Institute (ICVS), Braga, Portugal
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Couto MR, Gonçalves P, Catarino T, Araújo JR, Correia-Branco A, Martel F. The effect of oxidative stress upon the intestinal uptake of folic acid: in vitro studies with Caco-2 cells. Cell Biol Toxicol 2012; 28:369-81. [PMID: 22956110 DOI: 10.1007/s10565-012-9228-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 07/18/2012] [Indexed: 10/27/2022]
Abstract
Folic acid (FA) is a vitamin essential for normal cellular functions, growth, and development. Because humans cannot synthesize this micronutrient, it must be obtained from dietary sources through intestinal absorption. The intestinal tract is a major target for oxidative stress. Our aim was to investigate the effect of oxidative stress upon the uptake of FA by Caco-2 cells. Oxidative stress was induced by exposure of the cells to tert-butyl hydroperoxide (TBH) for 1 h. TBH (3,000 μM) induced an increase in biomarkers of oxidative stress, while maintaining cell viability and proliferation. In relation to the apical uptake of (3)H-FA, TBH (3,000 μM) reduced the cellular accumulation of (3)H-FA (10 nM), although the characteristics (kinetics, pH dependence, and inhibitory profile) of (3)H-FA uptake were not changed. This effect was associated with a decrease in the mRNA steady-state levels of proton-coupled folate transporter and folate receptor alpha and of the efflux transporter multidrug resistance protein 2. Moreover, TBH (3,000 μM) did not affect the noncarrier-mediated apical uptake of (3)H-FA. Finally, the effect of TBH upon (3)H-FA apical uptake was not dependent on protein kinase A, protein kinase C, mitogen-activated protein kinases, phosphoinositide 3-kinase, nuclear factor kappa B, and protein tyrosine kinases, but was completely prevented by dietary polyphenols (resveratrol, quercetin, and EGCG). These results suggest that oxidative stress at the intestinal level may result in a reduction in the intestinal absorption of dietary FA and that polyphenolic dietary components may offer protection against oxidative stress-induced inhibition of intestinal FA absorption.
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Affiliation(s)
- Mafalda R Couto
- Department of Biochemistry (U38-FCT), Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal
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Gonçalves P, Catarino T, Gregório I, Martel F. Inhibition of butyrate uptake by the primary bile salt chenodeoxycholic acid in intestinal epithelial cells. J Cell Biochem 2012; 113:2937-47. [DOI: 10.1002/jcb.24172] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Louro RO, Bento I, Matias PM, Catarino T, Baptista AM, Soares CM, Carrondo MA, Turner DL, Xavier AV. Conformational component in the coupled transfer of multiple electrons and protons in a monomeric tetraheme cytochrome. J Biol Chem 2001; 276:44044-51. [PMID: 11551953 DOI: 10.1074/jbc.m107136200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell metabolism relies on energy transduction usually performed by complex membrane-spanning proteins that couple different chemical processes, e.g. electron and proton transfer in proton-pumps. There is great interest in determining at the molecular level the structural details that control these energy transduction events, particularly those involving multiple electrons and protons, because tight control is required to avoid the production of dangerous reactive intermediates. Tetraheme cytochrome c(3) is a small soluble and monomeric protein that performs a central step in the bioenergetic metabolism of sulfate reducing bacteria, termed "proton-thrusting," linking the oxidation of molecular hydrogen with the reduction of sulfate. The mechano-chemical coupling involved in the transfer of multiple electrons and protons in cytochrome c(3) from Desulfovibrio desulfuricans ATCC 27774 is described using results derived from the microscopic thermodynamic characterization of the redox and acid-base centers involved, crystallographic studies in the oxidized and reduced states of the cytochrome, and theoretical studies of the redox and acid-base transitions. This proton-assisted two-electron step involves very small, localized structural changes that are sufficient to generate the complex network of functional cooperativities leading to energy transduction, while using molecular mechanisms distinct from those established for other Desulfovibrio sp. cytochromes from the same structural family.
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Affiliation(s)
- R O Louro
- Instituto de Tecnologia Quimica e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande, 6, Apt. 127, Oeiras 2780-156, Portugal
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Louro RO, Catarino T, LeGall J, Turner DL, Xavier AV. Cooperativity between electrons and protons in a monomeric cytochrome c(3): the importance of mechano-chemical coupling for energy transduction. Chembiochem 2001; 2:831-7. [PMID: 11948869 DOI: 10.1002/1439-7633(20011105)2:11<831::aid-cbic831>3.0.co;2-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To fully understand the structural bases for the mechanisms of biological energy transduction, it is essential to determine the microscopic thermodynamic parameters which describe the properties of each centre involved in the reactions, as well as its interactions with the others. These interactions between centres can then be interpreted in the light of structural features of the proteins. Redox titrations of cytochrome c(3) from Desulfovibrio desulfuricans ATCC 27774 followed by NMR and visible spectroscopy were analysed by using an equilibrium thermodynamic model. The network of homotropic and heterotropic cooperativities results in the coupled transfer of electrons and protons under physiological conditions. The microscopic characterisation allows the identification of several pairs of centres for which there are clear conformational (non-Coulombic) contributions to their coupling energies, thus establishing the existence of localised redox- and acid-base-linked structural modifications in the protein (mechano-chemical coupling). The modulation of interactions between centres observed for this cytochrome may be an important general phenomenon and is discussed in the framework of its physiological function and of the current focus of energy transduction research.
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Affiliation(s)
- R O Louro
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande, 6, Apt. 127, 2780 Oeiras, Portugal
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Abstract
In the analysis of kinetic data from multicentre redox proteins, it is essential to distinguish between the observable macroscopic rate constants and the structurally relevant microscopic properties. This distinction is complicated by the existence of interactions between centres. The problem is illustrated by the case of two interacting redox centres and generalised for the analysis of stopped-flow kinetic data for the reduction of cytochrome c(3), in which four redox centres and at least one proteolytic centre are mutually interacting. It is shown that fast intramolecular electron transfer, which is typical of many multicentre redox proteins, and, where present, fast proton exchange, ensure that only N rate constants can be measured for a protein with N redox centres. The equations that relate the observable macroscopic rate constants to the microscopic rate constants of individual centres depend on a set of parameters that can be approximated by using the Marcus theory of electron transfer together with a set of reasonable assumptions. The results are tested by fitting experimental data for the reduction of cytochrome c(3) by sodium dithionite, including its pH dependence.
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Affiliation(s)
- T Catarino
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande, 6, Apt. 127, 2780 Oeiras, Portugal.
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Louro RO, Catarino T, Turner DL, Piçarra-Pereira MA, Pacheco I, LeGall J, Xavier AV. Functional and mechanistic studies of cytochrome c3 from Desulfovibrio gigas: thermodynamics of a "proton thruster". Biochemistry 1998; 37:15808-15. [PMID: 9843386 DOI: 10.1021/bi981505t] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nuclear magnetic resonance and visible spectroscopies were used to determine the thermodynamic parameters of the four hemes in cytochrome c3 from Desulfovibrio gigas at 298 and 277 K and to investigate the mechanism of electron/proton energy transduction. Data obtained in the pH range from 5 to 9 were analyzed according to a model in which the hemes interact with each other (redox cooperativities) and with an ionizable center (redox-Bohr cooperativities). The results obtained at the two temperatures allow the deconvolution of the entropic contribution to the free energy of the four hemes, to the acid-base equilibrium of the ionizable center, and to the network of cooperativities among the five centers. The redox potentials of the hemes are modulated by the enthalpic contribution to the free energy, and evidence for the participation of the propionates of heme I in the redox-Bohr effect is presented. The network of interactions between the centers in this protein facilitates the concerted transfer of electrons and protons, in agreement with the "proton thruster" mechanism proposed for electronic to protonic energy transduction by cytochromes c3.
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Affiliation(s)
- R O Louro
- Instituto de Tecnologia Química e Biológica-Universidade Nova de Lisboa, Oeiras, Portugal
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Turner DL, Salgueiro CA, Catarino T, Legall J, Xavier AV. NMR studies of cooperativity in the tetrahaem cytochrome c3 from Desulfovibrio vulgaris. Eur J Biochem 1996; 241:723-31. [PMID: 8944758 DOI: 10.1111/j.1432-1033.1996.00723.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The thermodynamic properties of the Desulfovibrio vulgaris (Hildenborough) tetrahaem cytochrome c3 (Dvc3) are rationalised by a model which involves both homotropic (e-/e-) and heterotropic (e-/H+) cooperativity. The paramagnetic shifts of a methyl group from each haem of the Dvc3 have been determined in each stage of oxidation at several pH values by means of two-dimensional exchange NMR. The thermodynamic parameters are obtained by fitting the model to the NMR data and to redox titrations followed by visible spectroscopy. They show significant positive cooperativity between two of the haems whereas the remaining interactions appear to be largely electrostatic in origin. These parameters imply that the protein undergoes a proton-assisted two-electron transfer which can be used for energy transduction. Comparison with the crystal structure together with measurement of the kinetics of proton exchange suggest that the pH dependence is mediated by a charged residue(s) readily acessible to the solvent and close to haem I.
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Affiliation(s)
- D L Turner
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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Turner DL, Salgueiro CA, Catarino T, LeGall J, Xavier AV. Homotropic and heterotropic cooperativity in the tetrahaem cytochrome c3 from Desulfovibrio vulgaris. Biochim Biophys Acta 1994; 1187:232-5. [PMID: 8075117 DOI: 10.1016/0005-2728(94)90117-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The thermodynamic parameters which govern the homotropic (e-/e-) and heterotropic (e-/H+) cooperativity in the tetrahaem cytochrome c3 isolated from Desulfovibrio vulgaris (Hildenborough) were determined, using the paramagnetic shifts of haem methyl groups in the NMR spectra of intermediate oxidized states at different pH levels. A model is put forward to explain how the network of positive and negative cooperativities between the four haems and acid/base group(s) enables the protein to achieve a proton-assisted 2e- step.
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Affiliation(s)
- D L Turner
- Instituto de Tecnologia Química e Biolígica, Universidade Nova de Lisboa, Oeiras, Portugal
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Abstract
The kinetic aspects of the reduction process in cytochrome c3 from Desulfovibrio gigas have been investigated over a wide range of pH values ranging between pH 5.8 and pH 9.8. The data have been analyzed in the framework of an I2H4 interaction network coupled to a proton-linked equilibrium between two tertiary structures (Cornish-Bowden, A. & Koshland, D.E. Jr (1970) J. Biol. Chem. 245, 6241-6250). The kinetic rate constants for the reduction of the four hemes for the two tertiary conformations have been characterized in the framework of the thermodynamic network obtained from the equilibrium analysis (Coletta, M., Catarino, T., LeGall, J.J. & Xavier, A.V. (1991) Eur. J. Biochem. 202, 1101-1106). The intrinsic reduction rate constants determined by reaction with sodium dithionite for two hemes (namely heme 4 and heme 1) are significantly faster than those for the other two heme residues. In view of the equilibrium redox properties, heme 4 (with the fastest reduction rate) may then work as the kinetic electron-capturing site for the electrons from sodium dithionite. The transfer to hemes 2 and 3 then occurs by virtue of their free-energy levels at equilibrium. At our experimental conditions, there is also transfer of electrons to hemes 2 and 3 from heme 1, which is reduced at a slower rate than heme 4, thus contributing to the biphasic kinetics observed for the overall process. The kinetic parameters obtained are discussed in terms of the mechanism proposed for the coupling between the electron and proton transfer, as induced by the heme/heme cooperativity network.
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Affiliation(s)
- T Catarino
- Centro de Tecnologia Química e Biológica, Oeiras, Portugal
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Coletta M, Catarino T, LeGall J, Xavier AV. A thermodynamic model for the cooperative functional properties of the tetraheme cytochrome c3 from Desulfovibrio gigas. Eur J Biochem 1991; 202:1101-6. [PMID: 1662600 DOI: 10.1111/j.1432-1033.1991.tb16476.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A thermodynamic model is presented to describe the redox behaviour of the tetraheme cytochrome c3 from Desulfovibrio gigas. This molecule displays different intrinsic redox potentials for the four hemes and during the redox titration process, interactions among different hemes occur, thus altering the values of redox potentials according to which of the hemes are oxidized [Santos, H., Moura, J.J.G., Moura, I., LeGall, J. & Xavier, A.V. (1984) Eur. J. Biochem. 141, 283-296]. This complex cooperative behaviour [Xavier, A.V. (1986) J. Inorg. Biochem. 28, 239-243] has been analyzed here using an I2H4-interaction network [Cornish-Bowden, A. & Koshland, D.E. Jr (1970) J. Biol. Chem. 245, 6241-6250] coupled to a proton-linked equilibrium between two tertiary structures. Such a formalism, which requires a reduced number of parameters, is able to fully account quantitatively for the pH dependence of the NMR redox-titration curves. The 'redox-Bohr' effect is discussed in terms of the available structure and thermodynamic data and a functional mechanism is proposed.
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Affiliation(s)
- M Coletta
- CNR Center for Molecular Biology, University of Rome La Sapienza, Italy
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