697 research outputs found

    Haemoglobin Engineering: For fun and money

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    AbstractThe recent transplantation of an unusual allosteric effect from crocodile to human haemoglobin has implications for both molecular evolution and the engineering of artificial blood substitutes

    Oxidation-reduction potentials of D-amino acid oxidase.

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    Abstract This paper reports a study of the oxidation-reduction equilibrium of d-amino acid oxidase, a flavoprotein containing FAD. The oxidation-reduction potential at 50% oxidation (E½) is -0.004 volt at pH 7.0 and 20°, and therefore about 180 mv higher than that of the free coenzyme (FAD). This difference in oxidation-reduction potential may be described in terms of relative affinity of the apoenzyme for the reduced and oxidized forms of the coenzyme. On this basis the affinity constant for the binding of reduced FAD to the apoenzyme is about 106 higher than that of oxidized FAD. The curve relating E½ to pH is in the alkaline range consistent with a slope of about -0.058 volt per pH unit which corresponds to the difference of 1 proton between the oxidized and reduced forms of the enzyme. The apparent pK of the oxidation-linke group, which belongs to the oxidized form, is ∼7.1. The shape of the oxidation-reduction equilibrium curve of d-amino acid oxidase is pH dependent, the value of n increasing from about 1 at pH 8.6 to about 3, or more, at pH 6.6. Under these conditions, therefore, one must consider the existence of functional homotropic interactions between at least 2 FAD molecules. The pH dependence of the cooperative oxidation-reduction equilibrium is discussed in the framework of the theory of linked functions

    A Novel Type of Nitric-oxide Reductase ESCHERICHIA COLI FLAVORUBREDOXIN

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    Escherichia coli flavorubredoxin is a member of the family of the A-type flavoproteins, which are built by two core domains: a metallo-β-lactamase-like domain, at the N-terminal region, harboring a non-heme di-iron site, and a flavodoxin-like domain, containing one FMN moiety. The enzyme fromE. coli has an extra module at the C terminus, containing a rubredoxin-like center. The A-type flavoproteins are widespread among strict and facultative anaerobes, as deduced from the analysis of the complete prokaryotic genomes. In this report we showed that the recombinant enzyme purified from E. coli has nitric-oxide reductase activity with a turnover number of ∼15 mol of NO·mol enzyme−1·s−1, which was well within the range of those determined for the canonical hemeb3 -FeB containing nitric-oxide reductases (e.g. ∼10–50 mol NO·mol enzyme−1·s−1 for the Paracoccus denitrificans NOR). Furthermore, it was shown that the activity was due to the A-type flavoprotein core, as the rubredoxin domain alone exhibited no activity. Thus, a novel family of prokaryotic NO reductases, with a non-heme di-iron site as the catalytic center, was established

    Study of energetic properties of different tree organs in six Olea europaea L. cultivars

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    Pruning is an important horticultural practice for the management of olive orchards (Olea europaea L.) that generates a considerable amount of residues every year. Olive orchards are increasingly expanding beyond the Mediterranean Basin to new growing Countries (Australia, California, Argentina, Chile and Uruguay) and this will certainly lead to larger availability of pruning material. Currently, the interest in use of olive tree pruning residues for energy purposes is increasing but unfortunately, the information on the differences among organs of the tree, in terms of calorific value and ash content, is scarce. Another unknown aspect is the effect of cultivar vigour on dry matter partition among different tree organs, these are important traits to establish the energetic quality of pruning residues. The aim of this research was to study energetic aspects of six olive cultivars, largely grown in the Sicilian olive industry and characterized by different vigour. The trees taken into consideration in the study were selected in an experimental orchard to avoid any effect due to differences in environmental conditions and management. The energetic characteristics, calorific value and ash content, were evaluated for the various tree organs particularly shoots, leaves and branches; also root system was evaluated, although the roots can only be used once the trees are uprooted. Significant differences were observed in the calorific values among the different tree organs and the cultivars. Regarding the ash, shoots and leaves showed the highest content with respect to the other organs, thus causing a possible tendency in slagging with fouling and corrosion of boiler components

    Food and nutrition security discursive frames in the context of the Spanish economic crisis

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    [EN] The recent economic crisis in Spain has provoked a number of food and nutrition security (FNS) impacts that have fuelled a fragmented landscape of food-related debates, although these have not taken the form of a coherent and allembracing public discussion on national food security. This paper is an inductive analysis of such debates, mostly based on media coverage, in an attempt to disentangle the different discourse frames on FNS in Spain, and the role played by the economic crisis in the shaping and underpinning of such frames. For this purpose a frame matrix was constructed, paying particular attention to the stakeholders governance claims in order to confront frame-specific problems. Results show how stakeholders have used elements of the crisis to underpin or reinterpret their core arguments. In addition, governance claims have concentrated on the malfunctioning of the food chain, mostly due to unequal bargaining power, and the way this could be putting at risk crucial components of the food system and future FNS. Also, the short-termism of most stakeholders approaches obscures the long run threats to the Spanish food system.This research is part of the project "Assessment of the impact of global drivers of change on Europe's food security" (TRANSMANGO), granted by the EU under 7th Framework Programme, theme KBBE.2013.2.5-01, Grant agreement no: 613532. Authors gratefully appreciate the comments and suggestions made by the three anonymous reviewers and the editors of the Journal.OOrtiz Miranda, D.; Moreno Pérez, OM.; Arnalte Alegre, EV. (2016). Food and nutrition security discursive frames in the context of the Spanish economic crisis. Food Security. 8(3):665-677. https://doi.org/10.1007/s12571-016-0574-xS66567783Antentas, J. M., & Vivas, E. (2014). 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    Low-protein diets for chronic kidney disease patients: The Italian experience

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    open20Nutritional treatment has always represented a major feature of CKD management. Over the decades, the use of nutritional treatment in CKD patients has been marked by several goals. The first of these include the attainment of metabolic and fluid control together with the prevention and correction of signs, symptoms and complications of advanced CKD. The aim of this first stage is the prevention of malnutrition and a delay in the commencement of dialysis. Subsequently, nutritional manipulations have also been applied in association with other therapeutic interventions in an attempt to control several cardiovascular risk factors associated with CKD and to improve the patient's overall outcome. Over time and in reference to multiple aims, the modalities of nutritional treatment have been focused not only on protein intake but also on other nutrients.openBellizzi, Vincenzo; Cupisti, Adamasco; Locatelli, Francesco; Bolasco, Piergiorgio; Brunori, Giuliano; Cancarini, Giovanni; Caria, Stefania; De Nicola, Luca; Di Iorio, Biagio R; Di Micco, Lucia; Fiaccadori, Enrico; Garibotto, Giacomo; Mandreoli, Marcora; Minutolo, Roberto; Oldrizzi, Lamberto; Piccoli, Giorgina B; Quintaliani, Giuseppe; Santoro, Domenico; Torraca, Serena; Viola, Battista FBellizzi, Vincenzo; Cupisti, Adamasco; Locatelli, Francesco; Bolasco, Piergiorgio; Brunori, Giuliano; Cancarini, Giovanni; Caria, Stefania; De Nicola, Luca; Di Iorio, Biagio R; Di Micco, Lucia; Fiaccadori, Enrico; Garibotto, Giacomo; Mandreoli, Marcora; Minutolo, Roberto; Oldrizzi, Lamberto; Piccoli, Giorgina B; Quintaliani, Giuseppe; Santoro, Domenico; Torraca, Serena; Viola, Battista F
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