1,721,084 research outputs found
Structural characterization of HIU-hydrolase and OHCU-decarboxylase, two enzymes involved in the uric acid degradation
No full textThermal stability improvement of duble colorant C-phycocyanin from Spirulina platensis for food industry applications.
No full textC-Phycocyanin (C-PC) is a blue pigment in cyanobacteria, rhodophytes and cryptophytes with potential use as a value-added food colorant. Its stability was studied by examining the thermal degradation reactions in a range of temperature (25-80 C) before and after the addition of selected edible preservatives. The natural protein crosslinker methylglyoxal does not stabilize significantly C-PC whereas addition of honey or high concentration of sugars greatly diminish the blue color degradation occurring when C-PC is exposed to high temperature. Data show that the sugar preservative effect on the C-PC blue color is related to the final concentration of sugar added rather than the type of sugar. For this reason the best preservative was found to be fructose, which is the most soluble sugar among those tested, at saturation concentration. Exploratory sterilization studies have been carried out with six blue/green fructose syrups made by mixing C-PC with the natural yellow pigment Carthamus tinctorius. Both after a "low temperature" and a "high temperature" sterilization procedure the syrups remain clear and maintain their bright color with only partial blue color degradation. After the sterilization process, the syrups were monitored for two months, in such observation period the loss of blue color is minimal
Ligand Binding and Structural Analysis of a Human Putative Cellular Retinol-binding Protein
Full text linkThree cellular retinol-binding protein (CRBP) types (CRBP I, II, and III) with distinct tissue distributions and retinoid binding properties have been structurally characterized thus far. A human binding protein, whose mRNA is expressed primarily in kidney, heart, and transverse colon, is shown here to be a CRBP family member (human CRBP IV), according to amino acid sequence, phylogenetic analysis, gene structure organization, and x-ray structural analysis. Retinol binding to CRBP IV leads to an absorption spectrum distinct from a typical holo-CRBP spectrum and is characterized by an affinity (K-d = similar to200 nm) lower than those for CRBP I, II, and III, as established in direct and competitive binding assays. As revealed by mutagenic analysis, the presence in CRBP IV of His(108) in place of Gln(108) is not responsible for the unusual holo-CRBP IV spectrum. The 2-Angstrom resolution crystal structure of human apo-CRBP IV is very similar to those of other structurally characterized CRBPs. The side chain of Tyr(60) is present within the binding cavity of the apoprotein and might affect the interaction with the retinol molecule. These results indicate that human CRBP IV belongs to a clearly distinct CRBP subfamily and suggest a relatively different mode of retinol binding for this binding protein
Purification of bacteriocin AS-48 from an Enterococcus faecium strain and analysis of the gene cluster involved in its production
No full textThe cyclic bacteriocin AS-48 has previously been shown to be produced by Enterococcus faecalis strains. A bacteriocin has been purified from an E. faecium strain (E. faecium 7C5), and it has been found to possess molecular mass, cyclization and amino acid sequence typical of bacteriocin AS-48. In addition to the structural gene as-48A, the sequence analysis of the AS-48 gene cluster present in E. faecium 7C5 has revealed the presence of several putative coding regions presumably involved in bacteriocin production and immunity. The results of DNA hybridization assays have indicated that the AS-48 gene cluster and the gene pd78 are present on the same plasmid, possibly the pPD1 plasmid, in E. faecium 7C5
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
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
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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