1,267 research outputs found
Aspectos Descritivos em Congruencia e Divergencias: Estudo Comparativo Mercosul UE
No full textQuesto capitolo introduce uno studio di caso sullo spazio di convergenze-divergenze Unione Europea-Mercosul, in materia di politiche per l'istruzione superiore nell'ambito. Vengono introdotti progetti di cooperazione internazionale UE-AL nei quali si procura promuovere ambiti di convergenza per la mobilità accademica e studentesca. Si riflette, infine sugli impatti che tale cooperazione può avere nei contesti locali di pratica
Functional characterization of Plasmodium falciparum ferredoxin-NADP+ reductase
No full textApicomplexa are protozoan parasites responsible for infective diseases of major worldwide impact, like malaria or toxoplasmosis. We have identified and characterized a redox system of Toxoplasma gondii (1), comprising ferredoxin-NADP+ reductase and ferredoxin, which is of vegetal origin and has not a homolog in the human host, thus being possibly a novel drug target (2). This system is localized in the apicoplast, an organelle shown to be essential for parasite survival both in P. falciparum and T. gondii. Recently, we have demonstrated the ability of the redox system FNR/Fd of P. falciparum to reconstitute in vitro the electron transfer pathway to the enzyme LytB which catalyzes the last step of the mevalonate-independent isoprenoid biosynthesis in the apicoplast (3). Here, we report a thorough characterization of the ferredoxin-NADP+ reductase of P. falciparum (PfFNR). We have cloned and overproduced in Escherichia coli the PfFNR in soluble and active form. The recombinant PfFNR, purified to homogeneity, has been studied with respect to the spectral properties and the interaction with its protein partner P. falciparum ferredoxin. Steady-state and rapid kinetics studies show several differences between the P. falciparum redox system and those of both plants and T.gondii. Redox titration experiments indicate that redox potential of the FAD prosthetic group of PfFNR is by far more positive than that of photosynthetic FNRs. Inhibition studies with organic and transition metal salts are in progress as well as the screening of conditions to obtain crystals for X-ray structure analysis.
1 Pandini V., Caprini G., Thomsen N., Aliverti A., Seeber F., Zanetti G. (2002) J. Biol. Chem. 277, 48463-48471.
2 Seeber F., Aliverti A., Zanetti G. (2005) Curr. Pharm. Des. 11, 3159-3172.
3 Rohrich RC, Englert N, Troschke K, Reichenberg A, Hintz M, Seeber F, Balconi E, Aliverti A, Zanetti G, Kohler U, Pfeiffer M, Beck E, Jomaa H, Wiesner J. (2005) FEBS Lett. 579,6433-8
Esercizi di identificazione e caratterizzazione strutturale di composti organici
No full textQuesto eserciziario nasce dalla sentita esigenza degli autori di organizzare in modo razionale e rendere disponibile agli studenti il materiale didattico raccolto e utilizzato nei tanti anni dedicati a vario titolo all'insegnamento nei corsi istituzionali di metodi fisici in chimica organica per le lauree magistrali in Chimica e Tecnologia Farmaceutica e Biotecnologie del Farmaco. L'eserciziario è rivolto agli studenti dei corsi di laurea e laurea magistrale che nei diversi percorsi di studio affrontano per la prima volta le problematiche relative alla identificazione e caratterizzazione strutturale di composti organici
A plant-type enzyme as a putative target for novel antimalarial drugs : properties of the Plasmodium falciparum ferredoxin-NADP+ reductase
No full textApicomplexan parasites harbor a specific organelle, named apicoplast, which is related to plant non-photosynthetic plastids and displays a plant-like metabolism. The apicoplast has been shown to contain typical vegetal proteins, such as ferredoxin–NADP+ reductase (FNR) and ferredoxin (Fd) (1-2). Both proteins from Plasmodium falciparum (PfFNR and PfFd) have been produced in recombinant form and characterized (3). The PfFNR/PfFd couple was shown to be catalytically active in vitro yielding reducing power to support the activity of LytB (4), the last enzyme of the biosynthetic pathway for isoprenoid precursors, a known site of action of antiplasmodial compounds. On this basis, PfFNR has been proposed as a possible target for new antimalarial drugs (2).
The three-dimensional structure of PfFNR has been determined by X-ray crystallography (3). Compared to other plastidic-type FNRs, PfFNR displays a significantly lower catalytic efficiency and lower selectivity against NADH. These functional features are probably the consequence of the lack of protein positively-charges stabilizing the 2’-phosphate of the bound substrate. NADP(H) binding to PfFNR occurs through an induced-fit mechanism never observed in other FNRs. The conformational changes induced by binding to the enzyme of 2’-P-AMP, a NADP+ analogue, includes the partial unwinding of an α-helix localized in the NADP+-binding domain. Furthermore, the binding of NADP+ triggers the formation of a disulfide-stabilized homodimer resulting in the inactivation of PfFNR. This process, observed in vitro, could represent a physiologic mechanism regulating the enzyme activity.
Structure-based design of PfFNR inhibitors is in progress and has already yielded some active compounds, with inhibitory constants in the range of micromolar or lower.
1. Pandini V. et al. (2002) J. Biol. Chem. 277, 48463-48471
2. Seeber F. et al. (2005) Curr. Farm. Des. 11, 3159-7312
3. Milani et al. (2007) J. Mol. Biol. 367, 501-513
4. Röhrich R.C. et al. (2005) FEBS lett. 579, 6433-643
Plasmodium falciparum ferredoxin-NADP+ reductase : induced-fit transition in the NADP-binding domain and ligand-triggered dimerization and inactivation
No full textNew antimalarial drugs are urgently needed to tackle the spread of Plasmodium falciparum strains resistant to current pharmacological treatments. The recent completion of the genome sequence of this parasite (1) has considerably boosted the search of new drug targets. Plasmodia, as most protists belonging to the phylum Apicomplexa, possess a nonphotosyntetic plastid, dubbed the apicoplast (2), which is essential for parasite survival and has no counterpart in the human host (3). We have shown that the apicoplast of both T. gondii and P. falciparum contains a short plant-type electron transport chain, comprising ferredoxin NADP+ reductase (FNR) and ferredoxin (Fd) (4,5). Furthermore, we have demonstrated that such enzyme system is able to provide electrons to the enzyme LytB, which catalyzes the last step of the mevalonate-independent isoprenoid biosynthesis in the apicoplast (6). We have cloned and overproduced in E. coli both P. falciparum FNR (PfFNR) and Fd (PfFd). The two proteins have been purified, characterized and shown to be catalytically competent as an NADPH-dependent electron transfer system, though displaying specific functional features that distinguish them from their plant homologs. Recently, we have obtained the crystal structures of PfFNR both in free form and in complex with the substrate analog 2P-AMP, at 2.4 and 2.7 Å resolution, respectively. Surprisingly, PfFNR displayed structural properties unique to the P. falciparum enzyme. 2P-AMP binding was shown to trigger an unprecedented induced-fit transition in the NADP-binding domain. Prolonged incubation with NADP+ or 2P-AMP led to the formation of a disulfide-stabilized dimeric form of the enzyme, which was catalytically inactive. Insights in its three-dimensional structure indicate that PfFNR is particularly suited for the rational design of inhibitors, which could represent valuable leads in the development of antimalarial compounds.
1. Gardner, M. J., Hall, N., Fung, E., White, O., Berriman, M., Hyman, R. W., Carlton, J. M., et al. (2002) Nature 419, 498–511.
2. Foth, B. J. & McFadden, G. I. (2003) Int. Rev. Cytol. 224, 57–110.
3. Fichera, M. E. & Roos, D. S. (1997) Nature 390, 407–409.
4. Pandini, V., Caprini, G., Thomsen, N., Aliverti, A., Seeber, F. & Zanetti, G. (2002) J. Biol. Chem. 277, 48463–48471.
5. Seeber, F., Aliverti, A. & Zanetti, G. (2005) Curr. Pharm. Des. 11, 3159–3172.
6. Röhrich, R. C., Englert, N., Troschke, K., Reichenberg, A., Hintz, M., Seeber, F., Balconi, E., Aliverti, A., Zanetti, G., Kohler, U., Pfeiffer, M., Beck, E., Jomaa, H. & Wiesner, J. (2005) FEBS Lett. 579, 6433–6438
O Mercosul e Aspectos do Sustema Polìtico-Educacional: Objetivos e Avanços
No full textIl Mercosur, ovvero "Mercato Comune del Sud" nasce dall'iniziativa delle Reppubliche Argentina, Brasile, Paraguay ed Uruguay. Si tratta di un blocco transnazionale cui principali obiettivi erano in principio commerciali e politici, ma che evolvono verso interessi culturali ed educativi. Il presente capitolo introduce la prospettiva di cooperazione transnazionale in materia d'istruzione e formazione, con particolare riguardo alla tematica della formazione docent
A Uniao Europeia e Aspectos do Sistema Politico-Educacional: Engase a Agenda de Lisboa
No full textQuesto capitolo ha come obiettivo il conoscere il modello di sviluppo Europeo. Si fa un breve ex-cursus dall'Agenda di Lisbona verso gli obiettivi 2010. La Società dell'Apprendimento viene introdotta attraverso il Programma di Istruzione e Formazione 2010, così come il Programma specifico "Lifelong Learning" ovvero di apprendimento permanente. Vengono discussi i principi educativi alla base di tale cornice di politiche educativ
Hybrid multi-layered scaffolds produced via grain extrusion and electrospinning for 3D cell culture tests
No full textPurpose: The purpose of this paper is to focus on the production of scaffolds with specific morphology and mechanical behavior to satisfy specific requirements regarding their stiffness, biological interactions and surface structure that can promote cell-cell and cell-matrix interactions though proper porosity, pore size and interconnectivity. Design/methodology/approach: This case study was focused on the production of multi-layered hybrid scaffolds made of polycaprolactone and consisting in supporting grids obtained by Material Extrusion (ME) alternated with electrospun layers. An open source 3D printer was utilized, with a grain extrusion head that allows the production and distribution of strands on the plate according to the designed geometry. Square grid samples were observed under optical microscope showing a good interconnectivity and spatial distribution of the pores, while scanning electron microscope analysis was used to study the electrospun mats morphology. Findings: A good adhesion between the ME and electrospinning layers was achieved by compression under specific thermomechanical conditions obtaining a hybrid three-dimensional scaffold. The mechanical performances of the scaffolds have been analyzed by compression tests, and the biological characterization was carried out by seeding two different cells phenotypes on each side of the substrates. Originality/value: The structure of the multi-layered scaffolds demonstrated to play an important role in promoting cell attachment and proliferation in a 3D culture formation. It is expected that this design will improve the performances of osteochondral scaffolds with a strong influence on the required formation of an interface tissue and structure that need to be rebuilt
O Alcance da Long LIfe Learning na UE: Politicas Européias para a Educaçao Superior e Formaçao dos Professores
No full textL'obiettivo di questo capitolo è conoscere le basi, gli obiettivi e gli strumenti dello Spazio Europeo d'Istruzione Superiore. In questo contesto, vengono introdotte le principali linee di sviluppo del Processo di Bologna; così come gli strumenti di cui tale processo si serve: Diploma Supplement, Europass, European Credit Transfer System. Si sottolinea il supporto alla mobilità come politica portante nella generazione di nuove cittadinanze europee. Inoltre, viene analizzato il caso della formazione docente come caso di studio problematico nell'ambito dell'internazionalizzazione dell'istruzione superior
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