1,720,985 research outputs found
Archaeal elongation factor 1a from Sulfolobus solfataricus interacts with the eubacterial antibiotic GE2270A
No full textThe thiazolyl-peptide antibiotic GE2270A, an inhibitor of the elongation factor Tu from Escherichia coli (EcEF-Tu), was used to study the effects produced in the biochemical properties of the archaeal functional analogue elongation factor 1a from Sulfolobus solfa- taricus (SsEF-1a). GE2270A did not substantially affect the poly(U)-directed-poly(Phe) incorporation catalyzed by SsEF-1a and the formation of the ternary complex SsEF-1aÆGTPÆPhe-tRNAPhe. On the other hand, the antibiotic was able to increase the GDP/GTP exchange rate of SsEF-1a; nevertheless, this improvement was not associated with an increase in the catalytic activity of the enzyme. In fact, GE2270A inhibited both the intrinsic GTPase of SsEF-1a (GTPaseNa) and that stimulated by ribosomes. Interestingly, GTPaseNa of both intact and C-terminal-deleted SsEF-1a resulted in a greater sensi- tivity to the antibiotic with respect to SsEF-1a lacking both the M- and C-terminal domains. This result sug- gested that, similar to what is found for EcEF-Tu, the M domain of SsEF-1a is the region of the enzyme most responsible for the interaction with GE2270A. The dif- ferent behavior observed in the inhibition of protein synthesis with respect to EcEF-Tu can be ascribed to the different adaptive structural changes that have occurred in SsEF-1a during evolution
An Approach to Help in Cloud Model Choice for Academia Services’ Supplying
No full textIn academic institutions, there is frequently the need to provide new services, in a cloud model, to be used either in teaching or research activities. One of the main decisions to be addressed is related to the cloud model to adopt (private, public or hybrid), and what the mixing of functionalities to use for the hybrid one. In this paper a new approach is proposed to define a methodology to serve as a tool to be used as decision support for the ICT manager in order to help him in this decision. A simple and intuitive graph representation has been used. The methodology has been tested with a real case study on the provisioning of a new e-learning service for the university of the authors. The work has to be considered a tentative approach as a starting point to further researches in the same direction
Valine 114 Replacements in Archaeal Elongation Factor 1A Enhanced Its Ability To Interact with Aminoacyl-tRNA and Kirromycin
No full textValine 114 in the D109AAILVVA sequence of elongation factor 1R from the archaeon Sulfolobus solfataricus (SsEF-1R) was substituted with an acidic (V114E), basic (V114K), or cavity-forming (V114A) residue, and the effects on the biochemical properties of the factor were investigated. This sequence is well-conserved among most of eukaryal and eubacterial counterparts, and in the three-dimensional structure of SsEF-1R, V114 is located in a hydrophobic pocket near the first GDP-binding consensus sequence G13XXXXGK[T,S] [Vitagliano, L., Masullo, M., Sica, F., Zagari, A., and Bocchini, V. (2001) EMBO J. 20, 5305-5311]. These mutants displayed functions absent in the wild-type factor. In fact, although they exhibited a rate in poly(Phe) incorporation almost identical to that of SsEF-1R, V114K and V114A exhibited an affinity for GDP and GTP higher and a capability to bind heterologous aa-tRNA stronger than that elicited by SsEF-1R but similar to that of eubacterial EF-Tu. V114E instead displayed not only a weaker binding capability for aa-tRNA but also a lower affinity for GDP. The intrinsic GTPase activity of V114E was drastically reduced compared to those of SsEF-1R, V114K, and V114A. Interestingly, the decreased intrinsic GTPase activity of V114E was partially restored by kirromycin, an effect already observed for the G13A mutant of SsEF-1R [Masullo, M., Cantiello, P., de Paola, B., Catanzano, F., Arcari, P., and Bocchini, V. (2002) Biochemistry 41, 628-633]. Finally, the V114A substitution showed only a marginal effect on both the thermostability and thermophilicity of SsEF-1R, whereas V114K and V114E replacements strongly destabilized the molecule
CLONING AND EXPRESSION OF THE GENE ENCODING THE ELONGATION FACTOR 1A FROM THE LOWER THERMOPHILIC SULFOLOBUS STRAIN MT3
No full textGoing 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
A Conceptual Model for the General Data Protection Regulation
No full textThe widespread diffusion of Cloud paradigm and its approach based on delegation of resources to service providers, improved greatly the need of protecting personal data. Accordingly, in recent years, governments are going to define and apply new rules, that aims at protecting the personal space of each individual. From 2018, General Data protection Regulation (GDPR) applies in Europe, giving specific rights to each individual and imposing procedures to protect personal data. GDPR addresses a clear need of our social network-based society, but has the side effect of outlining the incapability of many actual enterprises, especially small and medium ones, to address such new requirements. In this paper the new Regulation is described with a conceptual map approach
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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