1,721,018 research outputs found
Sequential reconstitution of copper sites in the multicopper oxidase CueO
No full textCueO belongs to the family of multicopper oxidases which are characterized by the presence of multiple copper-binding sites with different structural and functional properties. These enzymes share the ability to couple the one-electron oxidation of substrate to reduction of oxygen to water by way of a functional unit composed of a mononuclear type 1 blue copper site, which is the entry site for electrons, and of a trinuclear copper cluster formed by type 2 and binuclear type 3 sites, where oxygen binding and reduction take place. The mechanism of copper incorporation in CueO has been investigated by optical and EPR spectroscopy. The results indicate unambiguously that the process is sequential, with type 1 copper being the first to be reconstituted, followed by type 2 and type 3 sites
Dolphin ceruloplasmin: The first proteolytically stable mammalian ceruloplasmin
No full text1. Ceruloplasmin, the blue protein of the plasma of vertebrates, was isolated from dolphin, a marine mammal. The protein showed overall physico-chemical parameters very similar to those of all other mammalian ceruloplasmins. The spectroscopic properties indicated a conservation of the copper binding sites. 2. Non-denaturing electrophoresis revealed a conformation similar to that of other mammalian ceruloplasmins. EPR spectroscopy and calorimetric analyses indicated a three-domain arrangement of the protein typical of "aged" ceruloplasmin. 3. Dolphin ceruloplasmin is the only mammalian ceruloplasmin insensitive to trypsin, plasmin or chymotrypsin. This property, however, does not result in a higher conformational stability of the molecule. Thus, susceptibility of ceruloplasmin to aging is not directly related to the lability to proteases, which is typical of all other mammalian ceruloplasmins so far studied
CERULOPLASMIN IN HUMAN PLASMA AND ITS RELATIONSHIPS WITH THE COPPER-ALBUMIN COMPLEX
No full textThe electron paramagnetic spectrum of human plasma is dominated, in the g = 2 region, by resonances from copper atoms bound to ceruloplasmin, and does not reveal the fraction of copper normally associated with albumin, except in a few cases, where a copper-albumin signal increases with time after blood withdrawl. This copper-albumin complex is responsible for a resonance at a g value below g = 2 in the spectrum of human serum, which has been recently attributed to a modified form of type 2 copper bound to ceruloplasmin [Rylkov, V. V., Tarasiev, M. Y. & Moshkov, K. A. (1991) Eur. J. Biochem. 197, 185-1891. In the plasma, copper associated to albumin comes from ceruloplasmin. Purified ceruloplasmin is unable to exchange copper with albumin, either purified or in plasma. It can not be ruled out that some serum components trigger the metal exchange, in a defence mechanism operating when ceruloplasmin leaks, by unknown processes, its copper content before discharging the metal into the various organs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Genistein up-regulates the iron efflux system in glial cells
No full textAstrocytes accumulate iron under chronic oxidative stress conditions in ageing and neurological disorders. The soybean isoflavone genistein possesses antioxidant properties and selective estrogen-like activities. Here, a possible role of genistein in modulation of iron transport was explored in glial cells. Genistein significantly increased iron export through estrogen receptor-beta-dependent p38 MAPK activation. Evidence is presented that this effect is associated to a p38 MAPK-triggered up-regulation of the iron export system made by ceruloplasmin and ferroportin-1, a pathway requiring activation of the transcription factor C/EBP. (C) 2010 Elsevier Ireland Ltd. All rights reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Studio sulle attivita' ossidasiche essido nitrico sintasiche nel Tunicato styela plicata: evidenze per la presenza di una cuproproteina cerulplasmin-like e di una ossido nitrico sintasi di tipo neuronale
No full textDottorato di ricerca in scienze biochemiche e biomolecolari. 11. ciclo. Docente guida Giovanni Musci. Coordinatore Antonio CambriaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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