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2001
Moura, I, Moura JJ.  2001.  Structural aspects of denitrifying enzymes, Apr. Curr Opin Chem Biol. 5:168-75., Number 2 AbstractWebsite

The reduction of nitrate to nitrogen gas via nitrite, nitric oxide and nitrous oxide is the metabolic pathway usually known as denitrification, a key step in the nitrogen cycle. As observed for other elemental cycles, a battery of enzymes are utilized, namely the reductases for nitrate, nitrite, nitric oxide and nitrous oxide, as well as multiple electron donors that interact with these enzymes, in order to carry out the stepwise reactions that involve key intermediates. Because of the importance of this pathway (of parallel importance to the nitrogen-fixation pathway), efforts are underway to understand the structures of the participating enzymes and to uncover mechanistic aspects. Three-dimensional structures have been solved for the majority of these enzymes in the past few years, revealing the architecture of the active metal sites as well as global structural aspects, and possible mechanistic aspects. In addition, the recognition of specific electron-transfer partners raises important questions regarding specific electron-transfer pathways, partner recognition and control of metabolism.

Raaijmakers, H, Teixeira S, Dias JM, Almendra MJ, Brondino CD, Moura I, Moura JJ, Romao MJ.  2001.  Tungsten-containing formate dehydrogenase from Desulfovibrio gigas: metal identification and preliminary structural data by multi-wavelength crystallography, Apr. J Biol Inorg Chem. 6:398-404., Number 4 AbstractWebsite

The tungsten-containing formate dehydrogenase (W-FDH) isolated from Desulfovibrio gigas has been crystallized in space group P2(1), with cell parameters a = 73.8 A, b = 111.3 A, c = 156.6 A and beta = 93.7 degrees. These crystals diffract to beyond 2.0 A on a synchrotron radiation source. W-FDH is a heterodimer (92 kDa and 29 kDa subunits) and two W-FDH molecules are present in the asymmetric unit. Although a molecular replacement solution was found using the periplasmic nitrate reductase as a search model, additional phasing information was needed. A multiple-wavelength anomalous dispersion (MAD) dataset was collected at the W- and Fe-edges, at four different wavelengths. Anomalous and dispersive difference data allowed us to unambiguously identify the metal atoms bound to W-FDH as one W atom with a Se-cysteine ligand as well as one [4Fe-4S] cluster in the 92 kDa subunit, and three additional [4Fe-4S] centers in the smaller 29 kDa subunit. The D. gigas W-FDH was previously characterized based on metal analysis and spectroscopic data. One W atom was predicted to be bound to two molybdopterin guanine dinucleotide (MGD) pterin cofactors and two [4Fe-4S] centers were proposed to be present. The crystallographic data now reported reveal a selenium atom (as a Se-cysteine) coordinating to the W site, as well as two extra [4Fe-4S] clusters not anticipated before. The EPR data were re-evaluated in the light of these new results.

Lodeiro, C, Pina F, Parola AJ, Bencini A, Bianchi A, Bazzicalupi C, Ciattini S, Giorgi C, Masotti A, Valtancoli B, de Melo JS.  2001.  Exploring the photocatalytic properties and the long-lifetime chemosensor ability of Cl-2 Ru(Bpy)(2)L (L=2,5,8,11,14-pentaaza 15 )-2,2 '-bipyridilophane), 2001. Inorganic Chemistry. 40:6813-6819. AbstractWebsite

In this work a new water-soluble long-lifetime chemosensor, containing a polyamine unit connected to a complexed Ru(II) metal center, is described. Its crystal structure has been characterized by X-ray analysis. The polyamine macrocyclic unit is capable of anchoring cationic or anionic substrates, according to its protonation state. Examples of electron transfer involving the ruthenium complex core and the bound substrate are presented. The photocatalytic ability of such a system is illustrated by the oxidation of iodide to iodine promoted by light absorption at 436 nm.

Calhorda, MJ, Drew MGB, Felix V, Fonseca LP, Gamelas CA, Godinho S, Goncalves IS, Hunstock E, Lopes JP, Parola AJ, Pina F, Romao CC, Santos AG.  2001.  Metal-metal interaction in polynuclear complexes with cyanide bridges: synthesis, characterisation, and theoretical studies, 2001. Journal of Organometallic Chemistry. 632:94-106. AbstractWebsite

The reaction of the cyanide anion [M(CO)(5)CN](-) (M = Cr or Mo) with metallocenes of Groups 4 and 6 produced polynuclear complexes of the type [CpCp 'M(CO){-NC-M ' (CO)(5)}]BF4 (M = M0, W; M ' = Mo, Cr, Cp '= Cp, Ind), Cp2TiCl{-NC-Mo(CO)(5)} and Cp2Ti{-NC-Mo(CO)(5)}(2). These complexes were characterised by H-1-, C-13- and Mo-95-NMR, IR and UV-vis spectroscopies, elemental analysis and examined by cyclic voltammetry. These methods show that the [M(CO)(5)CN]- ligands shift the electron density towards the metallocene centres. The complex [Cp2W(CO){-NC-Mo(CO)(5)}](+) is additionally examined by single crystal X-ray structure determination. The Density Functional Theory (DFT) calculations with the ADF program were performed on selected compounds to understand the nature of the redox processes taking place. Compared with a nitrile, the coordination of a [M(CO)-,CN]- fragment to the metallocene moiety does not significantly change the geometrical features. but leads to the stabilisation of the HOMO of the latter. with all the oxidation processes occurring in the pentacarbonyl moiety of the binuclear species. Time-dependent DFT calculations were used to identify the band appearing in the visible spectrum of Cp2TiCl{-NC-Mo(CO)(5)} as a Mo to Ti charge transfer. (C) 2001 Elsevier Science BN. All rights reserved.

Lodeiro, C, Parola AJ, Pina F, Bazzicalupi C, Bencini A, Bianchi A, Giorgi C, Masotti A, Valtancoli B.  2001.  Protonation and Zn(II) coordination by dipyridine-containing macrocycles with different molecular architecture. A case of pH-controlled metal jumping outside-inside the macrocyclic cavity, 2001. Inorganic Chemistry. 40:2968-2975. AbstractWebsite

The synthesis of the macrocyclic ligand 4,4 '-(2,5,8, 11,14-pentaaza[15])-2,2 ' -bipyridylophane (L3), which contains a pentaamine chain linking the 4,4 ' -positions of a 2,2 ' -dipyridine moiety, is reported. Protonation and Zn(II) complexation by L3 and by macrocycle L2, containing the same pentaamine chain connecting the 6,6 ' -positions of 2,2 ' -dipyridine, were studied by means of potentiometric, UV-vis, and fluorescent emission measurements. While in L2 all the nitrogen donor atoms are convergent inside the macrocyclic cavity, in L3 the heteroaromatic nitrogen atoms are located outside. Both ligands form mono- and dinuclear Zn(II) complexes in aqueous solution. In the mononuclear Zn(II) complexes with L2, the metal is coordinated inside the macrocyclic cavity, bound to the heteroaromatic nitrogen donors and three amine groups of the aliphatic chain. As shown by the crystal structure of the [ZnL2](2+) complex, the two benzylic nitrogens are not coordinated and facile protonation of the complex takes place at slightly acidic pH values. Considering the mononuclear [ZnL3](2+) complex, the metal is encapsulated inside the cavity, not coordinated by the dipyridine unit. Protonation of the complex occurs on the aliphatic polyamine chain and gives rise to translocation of the metal outside the cavity, bound to the, heteroaromatic nitrogens.

Borges, JP, Godinho MH, Martins AF, Trindade AC, Belgacem MN.  2001.  Cellulose-based composite films. Mechanics of composite materials. 37(3):257–264., Number 3: Springer AbstractWebsite

The mechanical and optical properties of cellulose-based composite films are investigated.It is shown that the use of toluene diisocyanate as a coupling agent and Avicel fibers as reinforcing elements give films with the highest mechanical characteristics. Using differential scanning calorimetry, it is also found that the glass transition temperature Tg of all the materials studied is below the room temperature and that the Tg increased with cross-linking and introduction of Avicel.

Amado, M.  2001.  Conservação Energética em Edifícios de Habitação. 6ª Conferência Nacional sobre a Qualidade do Ambiente. :846-848., Lisbon
Salgueiro, CA, da Costa PN, Turner DL, Messias AC, van Dongen WMAM, Saraiva LM, Xavier AV.  2001.  Effect of Hydrogen-Bond Networks in Controlling Reduction Potentials in Desulfovibrio vulgaris (Hildenborough) Cytochrome c3 Probed by Site-Specific Mutagenesis. Biochemistry. 40(32):9709-9716. AbstractWebsite

Cytochromes c3 isolated from Desulfovibrio spp. are periplasmic proteins that play a central role in energy transduction by coupling the transfer of electrons and protons from hydrogenase. Comparison between the oxidized and reduced structures of cytochrome c3 isolated from Desulfovibrio vulgaris (Hildenborough) show that the residue threonine 24, located in the vicinity of heme III, reorients between these two states [Messias, A. C., Kastrau, D. H. W., Costa, H. S., LeGall, J., Turner, D. L., Santos, H., and Xavier, A. V. (1998) J. Mol. Biol. 281, 719−739]. Threonine 24 was replaced with valine by site-directed mutagenesis to elucidate its effect on the redox properties of the protein. The NMR spectra of the mutated protein are very similar to those of the wild type, showing that the general folding and heme core architecture are not affected by the mutation. However, thermodynamic analysis of the mutated cytochrome reveals a large alteration in the microscopic reduction potential of heme III (75 and 106 mV for the protonated forms of the fully reduced and oxidized states, respectively). The redox interactions involving this heme are also modified, while the remaining heme−heme interactions and the redox−Bohr interactions are less strongly affected. Hence, the order of oxidation of the hemes in the mutated cytochrome is different from that in the wild type, and it has a higher overall affinity for electrons. This is consistent with the replacement of threonine 24 by valine preventing the formation of a network of hydrogen bonds, which stabilizes the oxidized state. The mutated protein is unable to perform a concerted two-electron step between the intermediate oxidation stages, 1 and 3, which can occur in the wild-type protein. Thus, replacing a single residue unbalances the global network of cooperativities tuned to control thermodynamically the directionality of the stepwise electron transfer and may affect the functionality of the protein.

Leal, A, Calado E.  2001.  Involuntary Rhythmic Leg Movements Time-Locked With the Respiratory Cycle. Pediatr Neurol . (25):405-408.
Borges, JP, Godinho MH, Belgacem MN, Martins AF.  2001.  New bio-composites based on short fibre reinforced hydroxypropylcellulose films. Composite interfaces. 8(3-4):233–241., Number 3-4: Taylor & Francis AbstractWebsite

The present work deals with the preparation and the characterisation of solid films, having thickness between 15 and 40 μm, prepared with hydroxypropyl cellulose (HPC) and different amounts of commercial cellulose fibres (0; 0.5; 10 and 15% w/w) (system A) and with 1,4-butyl diisocyanate (BDI), as a cross-linking agent (system B). Before the preparation of these films, the surface energy of cellulose fibres, as such and after purification with different solvents, was determined by Inverse Gas Chromatography (IGC), which gave the values of dispersive energy and acid-base properties of their surfaces. The tensile and photo-elastic properties of the solid films obtained were studied. There were no significant changes in Young's modulus between the two systems. However, as expected, the values of the elongation and those of the fracture stress were systematically higher for system B in comparison with system A. The same trend was found for the birefringence, measured at the same elongation values for the films obtained from both systems.

Pessanha, M, Brennan L, Xavier AV, Cuthbertson PM, Reid GA, Chapman SK, Turner DL, Salgueiro CA.  2001.  NMR structure of the haem core of a novel tetrahaem cytochrome isolated from Shewanella frigidimarina: identification of the haem-specific axial ligands and order of oxidation. FEBS Letters. 489(1):8-13. AbstractWebsite

The tetrahaem cytochrome isolated during anaerobic growth of Shewanella frigidimarina NCIMB400 is a small protein (86 residues) involved in electron transfer to Fe(III), which can be used as a terminal respiratory oxidant by this bacterium. A 3D solution structure model of the reduced form of the cytochrome has been determined using NMR data in order to determine the relative orientation of the haems. The haem core architecture of S. frigidimarina tetrahaem cytochrome differs from that found in all small tetrahaem cytochromes c3 so far isolated from strict anaerobes, but has some similarity to the N-terminal cytochrome domain of flavocytochrome c3 isolated from the same bacterium. NMR signals obtained for the four haems of S. frigidimarina tetrahaem cytochrome at all stages of oxidation were cross-assigned to the solution structure using the complete network of chemical exchange connectivities. Thus, the order in which each haem in the structure becomes oxidised was determined.

Amado, M.  2001.  Patologias do edifício do Grande Auditório da FCT – CAMPUS DA FACULDADE DE CIÊNCIAS E TECNOLOGIA. , Lisbon: Gabinete de Planeamento Físico e Gestão Ambiental da Faculdade de Ciências e Tecnologia da UNL
Filipe, SR, Severina E, Tomasz A.  2001.  The role of the murMN operon in penicillin resistance and antibiotic tolerance of Streptococcus pneumoniae. Microb. Drug Resist. 7:303-6.
Mano, JF, Lanceros-Méndez S, Nunes AM, Dionísio M.  2001.  Temperature Calibration in dielectric measurements. Journal of Thermal Analysis and Calorimetry. 65:37-49.Website
Batista, AG, Rodrigues JM, Ortigueira MD.  2001.  Time-Frequency and Time-Scale Characterisation of the Beat-by-Beat High-Resolution Electrocardiogram. Sixth Portuguese Conference on Biomedical Engineering Proceedings. Abstract

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Moniz, A.  2001.  Book review of Alice R. P. Abreu (org.): Flexible production and economic governance in Latin America. , Number http://ideas.repec.org/p/pra/mprapa/5937.html Abstract

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Moniz, A.  2001.  A coopera{\c c}ão entre equipas de trabalho em empresas em rede: vantagens para o desenvolvimento regional[Workteam Co-operation in Networked Companies: regional development advantages]. , Number 5920: University Library of Munich, Germany Abstract

Working teams in enterprise environment are considered as the most advanced forms of work organisation. This means the forms that can improve productivity quality of working life. Nevertheless, it prevails a slow development and dissemination of these advanced organisational forms in European companies. The reason for that lays in a complex linkage factors from social values to the economical pressures. But other factors are also related to the national systems of education training, to the different systems of industrial relations and technology policy.

Bazzicalupi, C, Bencini A, Berni E, Bianchi A, Giorgi C, Fusi V, Valtancoli B, Lodeiro C, Roque A, Pina F.  2001.  Coordination properties of a polyamine cryptand with two different binding moieties. A case of a pH-modulated antenna device based on a new Eu(III) cryptate complex. Inorganic Chemistry. 40:6172-6179., Number 24 AbstractWebsite
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Romão, MJ, Dias JM, Moura I.  2001.  Dissimilatory Nitrate Reductase. Handbook of Metalloproteins . (Messerschmidt, A., Huber, R., Poulos, T., Wieghardt, K., Eds.).:1075-1085. Abstract
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Correia dos Santos, MM, Paes de Sousa PM, Simões Gonçalves ML, Ascenso C, Moura I, Moura JJG.  2001.  Electrochemical studies of rubredoxin from Desulfovibrio vulgaris at modified electrodes. Journal of Electroanalytical Chemistry. 501:173-179., Number 1–2 AbstractWebsite
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Moniz, A, Gomes C, Machado T, Urze P.  2001.  Information Society, Work and the Generation of New Forms of Social Exclusion (SOWING): National Report (Portugal). , Number 6887: University Library of Munich, Germany Abstract

The choice over the Portuguese case studies was based on the sample constructed for the application of the firm questionnaires, during the second year of the SOWING project, 1999. This sample was fulfilled of firms among several activity sectors: textile, manufacturing, electronics, transports and software industry, based on NACE – codes (2 – digit level). Thus, we agreed to include in a new database the remaining questionnaires and construct a sample with 113 observations. Concerning the organisational change we make a distinction of three categories of change. First we analyse changes taking place at the inter-firm level (outsourcing, subcontracting, geographic relocation), followed by changes at the organisational level (deconcentration/decentralisation, reduction of hierarchical levels, introduction of cost and profit centres). The third kind of changes analysed will be those taking place at the workplace level (job enlargement/enrichment, changing character of work, work load). The Portuguese studied companies presents a relative uniform pattern considering the variables social competencies, practical knowledge, responsibility and specialized professional qualifications.

Dias, FB, Lima JC, Pierola IF, Horta A, Macanita AL.  2001.  Internal dynamics of poly(methylphenylsiloxane) chains as revealed by picosecond time resolved fluorescence. Journal of Physical Chemistry a. 105:10286-10295., Number 45 Abstract
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