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1993
Dionísio, M, Ramos MJJ, Williams G.  1993.  Molecular motions in poly(vinyl acetate) and in poly(vinyl acetate)/p-nitroaniline mixtures. Polymer. 34(19):4105-4110.Website
Romao, MJ, Barata BAS, Archer M, Lobeck K, Moura I, Carrondo MA, Legall J, Lottspeich F, Huber R, Moura JJG.  1993.  SUBUNIT COMPOSITION, CRYSTALLIZATION AND PRELIMINARY CRYSTALLOGRAPHIC STUDIES OF THE DESULFOVIBRIO-GIGAS ALDEHYDE OXIDOREDUCTASE CONTAINING MOLYBDENUM AND 2FE-2S CENTERS. European Journal of Biochemistry. 215:729-732., Number 3 AbstractWebsite
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1992
Moura, I, Tavares P, Moura JJ, Ravi N, Huynh BH, Liu MY, Legall J.  1992.  Direct spectroscopic evidence for the presence of a 6Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans (ATCC 27774), Mar 5. J Biol Chem. 267:4489-96., Number 7 AbstractWebsite

A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (delta EQ = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.

Ravi, N, Moura I, Costa C, Teixeira M, Legall J, Moura JJ, Huynh BH.  1992.  Mossbauer characterization of the tetraheme cytochrome c3 from Desulfovibrio baculatus (DSM 1743). Spectral deconvolution of the heme components, Mar 1. Eur J Biochem. 204:779-82., Number 2 AbstractWebsite

Mossbauer spectroscopy was used to study the tetraheme cytochrome c3 from Desulfovibrio baculatus (DSM 1743). Samples with different degrees of reduction were prepared using a redoxtitration technique. In the reduced cytochrome c3, all four hemes are reduced and exhibit diamagnetic Mossbauer spectra typical for low-spin ferrous hemes (S = 0). In the oxidized protein, the hemes are low-spin ferric (S = 1/2) and exhibit overlapping magnetic Mossbauer spectra. A method of differential spectroscopy was applied to deconvolute the four overlapping heme spectra and a crystal-field model was used for data analysis. Characteristic Mossbauer spectral components for each heme group are obtained. Hyperfine and crystal-field parameters for all four hemes are determined from these deconvoluted spectra.

Romao, MJ, Turk D, GomisRuth FX, Huber R, Schumacher G, Mollering H, Russmann L.  1992.  CRYSTAL-STRUCTURE ANALYSIS, REFINEMENT AND ENZYMATIC-REACTION MECHANISM OF N-CARBAMOYLSARCOSINE AMIDOHYDROLASE FROM ARTHROBACTER SP AT 2.0-ANGSTROM RESOLUTION. Journal of Molecular Biology. 226:1111-1130., Number 4 AbstractWebsite
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Moura, I, Tavares P, Moura JJG, Ravi N, Huynh BH, Liu MY, Legall J.  1992.  DIRECT SPECTROSCOPIC EVIDENCE FOR THE PRESENCE OF A 6FE CLUSTER IN AN IRON-SULFUR PROTEIN ISOLATED FROM DESULFOVIBRIO-DESULFURICANS (ATCC-27774). Journal Of Biological Chemistry. {267}:{4489-4496}., Number {7} Abstract

A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (DELTA-E(Q) = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.

Laber, B, GomisRuth FX, Romao MJ, Huber R.  1992.  ESCHERICHIA-COLI DIHYDRODIPICOLINATE SYNTHASE - IDENTIFICATION OF THE ACTIVE-SITE AND CRYSTALLIZATION. Biochemical Journal. 288:691-695. AbstractWebsite
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1991
Ferreira, LM, Lobo AM, Prabhakar S, MARCELOCURTO MJ, Rzepa HS, YI MY.  1991.  2-ACYL THIAZOLIUM SALTS AS SELECTIVE AGENTS FOR THE O-ACYLATION OF AROMATIC HYDROXYLAMINES, AUG 15. JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS. :1127-1128., Number 16 Abstract
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1990
Moura, I, Tavares P, Moura JJ, Ravi N, Huynh BH, Liu MY, Legall J.  1990.  Purification and characterization of desulfoferrodoxin. A novel protein from Desulfovibrio desulfuricans (ATCC 27774) and from Desulfovibrio vulgaris (strain Hildenborough) that contains a distorted rubredoxin center and a mononuclear ferrous center, Dec 15. J Biol Chem. 265:21596-602., Number 35 AbstractWebsite

A new type of non-heme iron protein was purified to homogeneity from extracts of Desulfovibrio desulfuricans (ATCC 27774) and Desulfovibrio vulgaris (strain Hildenborough). This protein is a monomer of 16-kDa containing two iron atoms per molecule. The visible spectrum has maxima at 495, 368, and 279 nm and the EPR spectrum of the native form shows resonances at g = 7.7, 5.7, 4.1 and 1.8 characteristic of a high-spin ferric ion (S = 5/2) with E/D = 0.08. Mossbauer data indicates the presence of two types of iron: an FeS4 site very similar to that found in desulforedoxin from Desulfovibrio gigas and an octahedral coordinated high-spin ferrous site most probably with nitrogen/oxygen-containing ligands. Due to this rather unusual combination of active centers, this novel protein is named desulfoferrodoxin. Based on NH2-terminal amino acid sequence determined so far, the desulfoferrodoxin isolated from D. desulfuricans (ATCC 27774) appears to be a close analogue to a recently discovered gene product from D. vulgaris (Brumlik, M.J., and Voordouw, G. (1989) J. Bacteriol. 171, 49996-50004), which was suggested to be a rubredoxin oxidoreductase. However, reduced pyridine nucleotides failed to reduce the desulforedoxin-like center of this new protein.

Dionísio, M, Ramos MJJ, Gonçalves RM.  1990.  The enthalpy and entropy of cavity formation in liquids and corresponding states principle. Canadian Journal of Chemistry. 68:1937-1949.Website
Dionísio, M, Almeida LN, Ramos MJ.  1990.  The n-alkane solvent effect on the dipole moment of the trans-1,2-dibromocyclohexane. Bulletin des Sociétés Chimiques Belges. 99(4):215-220.Website
1988
Ramos, MJJ, Dionísio M, Gonçalves R, Diogo H.  1988.  A further view on the calculation of the enthalpy of cavity formation in liquids. The influence of the cavity size and shape. Canadian Journal of Chemistry. 66(11):2894-2902.Website
1981
Thomson, AJ, Robinson AE, Johnson MK, Moura JJ, Moura I, Xavier AV, Legall J.  1981.  The three-iron cluster in a ferredoxin from Desulphovibrio gigas. A low-temperature magnetic circular dichroism study, Aug 28. Biochim Biophys Acta. 670:93-100., Number 1 AbstractWebsite

Ferredoxin II from Desulphovibrio gigas is a tetrameric protein containing a novel iron-sulphur cluster consisting of three iron atoms. The low-temperature magnetic circular dichroism (MCD) spectra of the oxidized and dithionite-reduced forms of ferredoxin II have been measured over the wavelength range approx. 300-800 nm. Both oxidation levels of the cluster are shown to be paramagnetic, although only the oxidized form gives an EPR signal. MCD magnetization curves have been constructed over the temperature range approx. 1.5-150 K and at fields between 0 and 5.1 Tesla. The curve for the oxidized protein can be fitted to a ground state of spin S = 1/2 with an isotropic g factor of 2.01. There is evidence for the thermal population of a low-lying electronic state above 50 K. The reduced protein gives a distinctive set of magnetization curves that are tentatively assigned to a ground state of S = 2, with a predominantly axial zero-field distortion that leaves the doublet Ms = +/-2 lowest in energy. The zero-field components have a maximum energy spread of approx. 15 cm-1. which places an upper limit of 4 cm-1 on the axial zero-field parameter D. The MCD spectra of the oxidized and reduced forms of the cluster are quite distinctive from one another. The spectra of the oxidized state are also different from those of oxidized high-potential iron protein from Chromatium and should provide a useful criterion for distinguishing between four- and three-iron clusters in their highest oxidation levels.

1977
Cammack, R, Rao KK, Hall DO, Moura JJ, Xavier AV, Bruschi M, Legall J, Deville A, Gayda JP.  1977.  Spectroscopic studies of the oxidation-reduction properties of three forms of ferredoxin from Desulphovibrio gigas, Feb 22. Biochim Biophys Acta. 490:311-21., Number 2 AbstractWebsite

Electron paramagnetic resonance spectra were recorded of three forms of Desulphovibrio gigas ferredoxin, FdI, FdI' and FdII. The g = 1.94 signal seen in dithionite-reduced samples is strong in FdI, weaker in FdI' and very small in FdII. The g = 2.02 signal in the oxidized proteins is weak in FdI and strongest in FdII. It is concluded that most of the 4Fe-4S centres in FdI change between states C- and C2-; FdI' contain both types of centre. There is no evidence that any particular centre can change reversibly between all three oxidation states. Circular dichroism spectra show differences between FdI and FdII even in the diamagnetic C2- state. The redox potentials of the iron-sulphur centres of the three oligomers (forms) are different. After formation of the apo-protein of FdII and reconstitution with iron and sulphide, the protein behaves more like FdI, showing a strong g = 1.94 signal in the reduced states.

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