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The small iron-sulfur protein from the ORP operon binds a [2Fe-2S] cluster, Maiti, B. K., Moura I., Moura J. J. G., and Pauleta S. R. , Biochim Biophys Acta, Volume 1857, p.1422-1429, (2016) Website
Rearrangement of Mo-Cu-S Cluster Reflects the Structural Instability of Orange Protein Cofactor, Maiti, B. K., Avilés T., Carepo M. S., Moura I., S.R. Pauleta, and Moura J. J. G. , Z Anorg Allg Chem, Volume 639, p.1361-1364, (2013)
Designed Metal-ATCUN Derivatives: Redox and Non-redox-Based Applications Relevant for Chemistry, Biology, and Medicine, Maiti, B. K., Govil N., Kundu T., and J.J.G. Moura , iScience, Volume 23, p.101792, (2020)
Rubredoxins derivatives: Simple sulphur-rich coordination metal sites and its relevance for Biology and Chemistry, Maiti, B. K., Almeida R. M., Moura I., and Moura J. J. G. , Coord Chem Rev, Volume 352, p.379-397, (2017)
Synthesis of [MoS4]2 – M (M = Cu and Cd) clusters: Potential NMR structural probes for orange protein, Maiti, B. K., Avilés T., Matzapetakis M., Moura I., Pauleta S. R., and Moura J. J. G. , Eur J Inorg Chem , Volume 2012, p.4159-4166, (2012)
NiII -ATCUN-catalyzed tyrosine nitration in the presence of nitrite and sulfite, Maiti, B. K., Maia L. B., Moura I., and Moura J. J. G. , Chem Eur J, Volume 25, p.4309-4314, (2019) Website
Insights into the molybdenum/copper heterometallic cluster assembly in the orange protein: probing intermolecular interactions with an artificial metal-binding ATCUN tag, Maiti, B. K., Almeida R. M., Maia L. B., Moura I., and Moura J. J. G. , Inorg Chem, Volume 56, p.8900-8911, (2017) Website
One Electron Reduced Square Planar Bis(benzene-1,2-dithiolato) Copper Dianionic Complex and Redox Switch by O2/HO-, Maiti, B. K., Maia L. B., Pal K., Pakira B., Aviles T., Moura I., Pauleta S. R., Nuñez J. L., Rizzi A. C., Brondino C. D., Sarkar S., and Moura J. J. G. , Inorg Chem, Volume 53, p.12799-12808, (2014)
Sulfide and transition metals - A partnership for life, Maiti, B. K., Maia L. B., and Moura J. J. G. , J Inorg Biochem, Volume 227, p.111687, (2022) Website
Substrate-dependent modulation of the enzymatic catalytic activity: Reduction of nitrate, chlorate and perchlorate by respiratory nitrate reductase from Marinobacter hydrocarbonoclasticus 617, Marangon, J., de Sousa Paes P. M., Moura I., Brondino C. D., Moura J. J., and González P. J. , Biochim Biophys Acta, Volume 1817, Issue 7, p.1072-1082, (2012)
Kinetic and structural studies of aldehyde oxidoreductase from Desulfovibrio gigas reveal a dithiolene-based chemistry for enzyme activation and inhibition by H2O2, Marangon, J., Correia H. D., Brondino C. D., Moura J. J. G., Romao M. J., Gonzalez P. J., and Santos-Silva T. , PLoS One, Volume 8, p.e83234, (2013)
Conversion of adrenaline to indolic derivatives by the human erythrocyte plasma membrane, Marques, F., Duarte R. O., Moura J. J., and Bicho M. P. , Biol Signals, Sep-Oct, Volume 5, Number 5, p.275-82, (1996) AbstractWebsite

The conversion of adrenaline to aminochromes by the human erythrocyte plasma membranes at pH 9.5 was shown to be a complex reaction that proceeded at least by two distinct phases. The first one, corresponding to the formation of adrenochrome, is catalyzed in the presence of the membranes, suggesting the involvement of an enzyme-mediated process. Active oxygen species were identified as intermediates during this phase. Oxygen radical scavengers (catalase and superoxide dismutase) suggested H2O2 and O2- involvement. Adrenochrome formation was stimulated by NADH indicating the participation of another enzyme (NADH dehydrogenase) which is known to be present in the human erythrocyte plasma membrane. The second phase, corresponding to the disappearance of adrenochrome, is also stimulated by NADH and inhibited in the presence of the membranes. In this reaction, adrenochrome is converted to aminochromes via adrenochrome semiquinone. The formation of radical species is demonstrated by EPR spectroscopy. The results led to the proposal of a mechanism for the formation of adrenochrome and other oxidation products from adrenaline.

Multifrequency EPR Study of Fe(3+) and Co(2+) in the Active Site of Desulforedoxin, Mathies, G., Almeida R. M., Gast P., Moura J. J., and Groenen E. J. , J Phys Chem B, Volume 116, Issue 24, p.7122-7128, (2012)
Continuous-wave EPR at 275GHz: application to high-spin Fe(3+) systems, Mathies, G., Blok H., Disselhorst J. A., Gast P., van der Meer H., Miedema D. M., Almeida R. M., Moura J. J., Hagen W. R., and Groenen E. J. , J Magn Reson, May, Volume 210, Number 1, p.126-32, (2011) AbstractWebsite

The 275GHz electron-paramagnetic-resonance spectrometer we reported on in 2004 has been equipped with a new probe head, which contains a cavity especially designed for operation in continuous-wave mode. The sensitivity and signal stability that is achieved with this new probe head is illustrated with 275GHz continuous-wave spectra of a 1mM frozen solution of the complex Fe(III)-ethylenediamine tetra-acetic acid and of 10mM frozen solutions of the protein rubredoxin, which contains Fe(3+) in its active site, from three different organisms. The high quality of the spectra of the rubredoxins allows the determination of the zero-field-splitting parameters with an accuracy of 0.5GHz. The success of our approach results partially from the enhanced absolute sensitivity, which can be reached using a single-mode cavity. At least as important is the signal stability that we were able to achieve with the new probe head.

Comparative electrochemical behavior of cytochrome c on aqueous solutions containing choline-based room temperature ionic liquids, Matias, S. C., Lourenço N. M. T., Fonseca J. P., and Cordas C. M. , ChemistrySelect, Volume 2, p.8701–8705, (2017) Website
A single histidine is required for activity of cytochrome c peroxidase from Paracoccus denitrificans, McGinnity, D. F., Devreese B., Prazeres S., Van Beeumen J., Moura I., Moura J. J., and Pettigrew G. W. , J Biol Chem, May 10, Volume 271, Number 19, p.11126-33, (1996) AbstractWebsite

The diheme cytochrome c peroxidase from Paracoccus denitrificans was modified with the histidine-specific reagent diethyl pyrocarbonate. At low excess of reagent, 1 mol of histidine was modified in the oxidized enzyme, and modification was associated with loss of the ability to form the active state. With time, the modification reversed, and the ability to form the active state was recovered. The agreement between the spectrophotometric measurement of histidine modification and radioactive incorporation using a radiolabeled reagent indicated little modification of other amino acids. However, the reversal of histidine modification observed spectrophotometrically was not matched by loss of radioactivity, and we propose a slow transfer of the ethoxyformyl group to an unidentified amino acid. The presence of CN- bound to the active peroxidatic site of the enzyme led to complete protection of the essential histidine from modification. Limited subtilisin treatment of the native enzyme followed by tryptic digest of the C-terminal fragment (residues 251-338) showed that radioactivity was located in a peptide containing a single histidine at position 275. We propose that this conserved residue, in a highly conserved region, is central to the function of the active mixed-valence state.

The methylenetetrahydrofolate reductase (MTHFR) 677C-->T mutation and cardiovascular risk--A case of ischemic stroke and acute myocardial infarction, Melo, M., Gaspar E., Madeira S., de Moura P., Alexandrino B., and de Moura J. J. , Rev Port Cardiol, Jan, Volume 24, Number 1, p.89-99, (2005) AbstractWebsite

The authors report the case of a 39-year-old male patient who had an ischemic stroke (complete infarction of right anterior cerebral circulation) and an acute myocardial infarction during the same year. Molecular study revealed he was homozygous for the 677C-->T mutation in the gene coding for methylenetetrahydrofolate reductase, a key enzyme of folate metabolism; deficiency of this enzyme is associated with increased cardiovascular risk and neurological lesions. Some considerations are put forward about hyperhomocysteinemia and the MTHFR 677C-->T mutation as cardiovascular risk factors.

Construction of effective disposable biosensors for point-of-care testing of nitrite, Monteiro, T., Rodrigues P. R., Gonçalves A. L., Moura J. J. G., Anorga L., Jubete E., Piknova B., Schechter A. N., Silveira C. M., and Almeida M. G. , Talanta, Volume 142, p.246-251, (2015)
Structure of the tetraheme cytochrome from Desulfovibrio desulfuricans ATCC 27774: X-ray diffraction and electron paramagnetic resonance studies, Morais, J., Palma P. N., Frazao C., Caldeira J., Legall J., Moura I., Moura J. J., and Carrondo M. A. , Biochemistry, Oct 3, Volume 34, Number 39, p.12830-41, (1995) AbstractWebsite

The three-dimensional X-ray structure of cytochrome c3 from a sulfate reducing bacterium, Desulfovibrio desulfuricans ATCC 27774 (107 residues, 4 heme groups), has been determined by the method of molecular replacement [Frazao et al. (1994) Acta Crystallogr. D50, 233-236] and refined at 1.75 A to an R-factor of 17.8%. When compared with the homologous proteins isolated from Desulfovibrio gigas, Desulfovibrio vulgaris Hildenborough, Desulfovibrio vulgaris Miyazaki F, and Desulfomicrobium baculatus, the general outlines of the structure are essentialy kept [heme-heme distances, heme-heme angles, His-His (axial heme ligands) dihedral angles, and the geometry of the conserved aromatic residues]. The three-dimensional structure of D. desulfuricans ATCC 27774 cytochrome c3Dd was modeled on the basis of the crystal structures available and amino acid sequence comparisons within this homologous family of multiheme cytochromes [Palma et al. (1994) Biochemistry 33, 6394-6407]. This model is compared with the refined crystal structure now reported, in order to discuss the validity of structure prediction methods and critically evaluate the steps used to predict protein structures by homology modeling. The four heme midpoint redox potentials were determined by using deconvoluted electron paramagnetic resonance (EPR) redox titrations. Structural criteria (electrostatic potentials, heme ligand orientation, EPR g values, heme exposure, data from protein-protein interaction studies) are invoked to assign the redox potentials corresponding to each specific heme in the three-dimensional structure.

Study of the spin-spin interactions between the metal centers of Desulfovibrio gigas aldehyde oxidoreductase: identification of the reducible sites of the [2Fe-2S]1+,2+ clusters, More, C., Asso M., Roger G., Guigliarelli B., Caldeira J., Moura J., and Bertrand P. , Biochemistry, Aug 30, Volume 44, Number 34, p.11628-35, (2005) AbstractWebsite

The aldehyde oxidoreductase from Desulfovibrio gigas belongs to the family of molybdenum hydroxylases. Besides a molybdenum cofactor which constitutes their active site, these enzymes contain two [2Fe-2S](2+,1+) clusters which are believed to transfer the electrons provided by the substrate to an acceptor which is either a FAD group or an electron-transferring protein. When the three metal centers of D. gigas AOR are simultaneously paramagnetic, splittings due to intercenter spin-spin interactions are visible when the EPR spectra are recorded at low temperatures. By studying quantitatively these interactions with a model based on the X-ray crystal structure, which takes into consideration the interactions between the magnetic moments carried by all the metal sites of the system, it is possible to determine the location of the reducible sites of the [2Fe-2S] clusters. When combined with the electron-transfer pathways proposed on the basis of the X-ray crystal structure, the results provide a detailed description of the electron-transfer system of D. gigas AOR.

Structural model of the Fe-hydrogenase/cytochrome c553 complex combining transverse relaxation-optimized spectroscopy experiments and soft docking calculations, Morelli, X., Czjzek M., Hatchikian C. E., Bornet O., Fontecilla-Camps J. C., Palma N. P., Moura J. J., and Guerlesquin F. , J Biol Chem, Jul 28, Volume 275, Number 30, p.23204-10, (2000) AbstractWebsite

Fe-hydrogenase is a 54-kDa iron-sulfur enzyme essential for hydrogen cycling in sulfate-reducing bacteria. The x-ray structure of Desulfovibrio desulfuricans Fe-hydrogenase has recently been solved, but structural information on the recognition of its redox partners is essential to understand the structure-function relationships of the enzyme. In the present work, we have obtained a structural model of the complex of Fe-hydrogenase with its redox partner, the cytochrome c(553), combining docking calculations and NMR experiments. The putative models of the complex demonstrate that the small subunit of the hydrogenase has an important role in the complex formation with the redox partner; 50% of the interacting site on the hydrogenase involves the small subunit. The closest contact between the redox centers is observed between Cys-38, a ligand of the distal cluster of the hydrogenase and Cys-10, a ligand of the heme in the cytochrome. The electron pathway from the distal cluster of the Fe-hydrogenase to the heme of cytochrome c(553) was investigated using the software Greenpath and indicates that the observed cysteine/cysteine contact has an essential role. The spatial arrangement of the residues on the interface of the complex is very similar to that already described in the ferredoxin-cytochrome c(553) complex, which therefore, is a very good model for the interacting domain of the Fe-hydrogenase-cytochrome c(553).

Heteronuclear NMR and soft docking: an experimental approach for a structural model of the cytochrome c553-ferredoxin complex, Morelli, X., Dolla A., Czjzek M., Palma P. N., Blasco F., Krippahl L., Moura J. J., and Guerlesquin F. , Biochemistry, Mar 14, Volume 39, Number 10, p.2530-7, (2000) AbstractWebsite

The combination of docking algorithms with NMR data has been developed extensively for the studies of protein-ligand interactions. However, to extend this development for the studies of protein-protein interactions, the intermolecular NOE constraints, which are needed, are more difficult to access. In the present work, we describe a new approach that combines an ab initio docking calculation and the mapping of an interaction site using chemical shift variation analysis. The cytochrome c553-ferredoxin complex is used as a model of numerous electron-transfer complexes. The 15N-labeling of both molecules has been obtained, and the mapping of the interacting site on each partner, respectively, has been done using HSQC experiments. 1H and 15N chemical shift analysis defines the area of both molecules involved in the recognition interface. Models of the complex were generated by an ab initio docking software, the BiGGER program (bimolecular complex generation with global evaluation and ranking). This program generates a population of protein-protein docked geometries ranked by a scoring function, combining relevant stabilization parameters such as geometric complementarity surfaces, electrostatic interactions, desolvation energy, and pairwise affinities of amino acid side chains. We have implemented a new module that includes experimental input (here, NMR mapping of the interacting site) as a filter to select the accurate models. Final structures were energy minimized using the X-PLOR software and then analyzed. The best solution has an interface area (1037.4 A2) falling close to the range of generally observed recognition interfaces, with a distance of 10.0 A between the redox centers.

Electrochemical studies of the hexaheme nitrite reductase from Desulfovibrio desulfuricans ATCC 27774, Moreno, C., Costa C., Moura I., Legall J., Liu M. Y., Payne W. J., Van Dijk C., and Moura J. J. , Eur J Biochem, Feb 15, Volume 212, Number 1, p.79-86, (1993) AbstractWebsite

The electron-transfer kinetics between three different mediators and the hexahemic enzyme nitrite reductase isolated from Desulfovibrio desulfuricans (ATCC 27774) were investigated by cyclic voltammetry and by chronoamperometry. The mediators, methyl viologen, Desulfovibrio vulgaris (Hildenborough) cytochrome c3 and D. desulfuricans (ATCC 27774) cytochrome c3 differ in structure, redox potential and charge. The reduced form of each mediator exchanged electrons with nitrite reductase. Second-order rate constants, k, were calculated on the basis of the theory for a simple catalytic mechanism and the results, obtained by cyclic voltammetry, were compared with those obtained by chronoamperometry. Values for k are in the range 10(6)-10(8) M-1 s-1 and increase in the direction D. desulfuricans cytochrome c3-->D. vulgaris cytochrome c3-->methyl viologen. An explanation is advanced on the basis of electrostatic interactions and relative orientation between the partners involved. Chronoamperometry (computer controlled) offers advantages over cyclic voltammetry in the determination of homogeneous rate constants (faster, more accurate and better reproducibility). Direct, unmediated electrochemical responses of the hexaheme nitrite reductase were also reported.

Redox properties of Desulfovibrio gigas [Fe3S4] and [Fe4S4] ferredoxins and heterometal cubane-type clusters formed within the [Fe3S4] core. Square wave voltammetric studies, Moreno, C., Macedo A. L., Moura I., Legall J., and Moura J. J. , J Inorg Biochem, Feb 15, Volume 53, Number 3, p.219-34, (1994) AbstractWebsite

The same polypeptide chain (58 amino acids, 6 cysteines) is used to build up two ferredoxins in Desulfovibrio gigas a sulfate reducing organism. Ferredoxin II (FdII) contains a single [Fe3S4] core and ferredoxin I (FdI) mainly a [Fe4S4] core. The [Fe3S4] core can readily be interconverted into a [Fe4S4] complex (J.J.G. Moura, I. Moura, T.A. Kent, J.D. Lipscomb, B.H. Huynh, J. LeGall, A.V. Xavier, and E. Munck, J. Biol. Chem. 257, 6259 (1982)). This interconversion process suggested that the [Fe3S4] core could be used as a synthetic precursor for the formation of heterometal clusters. Co, Zn, Cd, and Ni derivatives were produced (I. Moura, J.J.G. Moura, E. Munck, V. Papaephthymiou, and J. LeGall, J. Am. Chem. Soc. 108, 349 (1986), K. Sureurs, E. Munck, I. Moura, J.J.G. Moura, and J. LeGall, J. Am. Chem. Soc. 109, 3805 (1986), and A.L. Macedo, I. Moura, J.J.G. Moura, K. Surerus, and E. Munck, unpublished results). The redox properties of a series of heterometal clusters (MFe3S4] are assessed using direct electrochemistry (square wave voltammetry--SWV) promoted by Mg(II) at a glassy carbon electrode (derivatives: Cd (-495 mV), Fe (-420 mV), Ni (-360 mV), and Co (-245 mV) vs normal hydrogen electrode (NHE)). In parallel, the electrochemical behavior (cyclic voltammetry--CV, differential pulse voltammetry--DPV and SWV) of FdI and FdII were investigated as well as the cluster interconversion process. In addition to the +1/0 (3Fe cluster) and +2/+1 (4Fe cluster) redox transitions, a very negative redox step, at -690 mV, was detected for the 3Fe core, reminiscent of a postulated further 2e- reduction step, as proposed for D. africanus ferredoxin III by F.A. Armstrong, S.J. George, R. Cammack, E.C. Hatchikian, and A.J. Thomson, Biochem. J. 264, 265 (1989). The electrochemical redox potential values are compared with those determined by independent methods (namely by electron paramagnetic resonance (EPR) and visible spectroscopy).