1,721,166 research outputs found
Synthesis and evaluation of antiparasitic activities of new 4-[5-(4-phenoxyphenyl)-2H-pyrazol-3-yl]morpholine derivatives
No full textA series of new 4-[5-(4-phenoxyphenyl)-2H-pyrazol-3-yl]morpholine derivatives, prepared by two synthetic routes, were in vitro assayed against three Trypanosoma strains, Leishmania donovani, and Plasmodium falciparum K1. Seven out of 17 compounds showed moderate to very good activity against blood stage T. b. rhodesiense, with 10 and 17 exhibiting highest potency (IC 50 of 1.0 and 1.1 μM. respectively). Interestingly, the β-diketone precursors 1-3 had good antitrypanosomal activity toward the insect stage, with IC50 values of 1.0-3.4 μM. Among different compounds with moderate activity against T. cruzi, compound 17 showed the lowest IC50 value of 9.5 μM; thus, the series seemed to act selectively toward the different Trypanosoma parasites. Eight compounds were moderately active against L. donovani, with 2, 3, and 12 being the most promising ones (IC50 values of 2.3-5.2 μM), whereas compound 14 was the only derivative with good activity against P. falciparum (IC50 of 3.7 μM). © 2007 American Chemical Society
The Role of the N-Terminal Domain in the Regulation of the "Constitutively Active" Conformation of Protein Kinase CK2 alpha: Insight from a Molecular Dynamics Investigation
No full textProtein kinase CK2 is an extremely well-conserved pleiotropic protein kinase with a growing list of substrates, the majority of which are proteins implicated in signal transduction, gene expression, and transcription-related functions. Protein kinase CK2 is a ubiquitous heterotetrameric serine/threonine protein kinase made up of two α or α' catalytic subunits and two β regulatory subunits. Moreover, protein kinase CK2 is defined as a "constitutively active" protein kinase in contrast to most other protein kinases characterized by the presence of distinct conformations associated with the active and inactive states. As previously demonstrated by in vitro mutation studies, CK2 activity is substantially regulated by the interaction between the N-terminal tail and the kinase domain. In fact, progressive deletions of the N-terminal tail show a decrease in the activity of the kinase. Even if the detrimental effects of Δ2-12 deletion can be partially reversed by the addition of a CK2β subunit, deletions Δ2-12 and Δ2-30 progressively decrease the basal activity of CK2. In particular, as experimentally demonstrated, the Δ2-12 N-terminal deletion affects both the K(M) value for ATP and for the substrate peptide, and the k(cat) value of CK2α. In this work, molecular dynamics (MD) simulations were carried out on wild-type (wt), Δ2-12 and Δ2-30 deletion mutants of CK2α in order to explore the role of the N-terminal tail on the conformational behavior of CK2. Furthermore, classical MD simulations were carried out to assess the anticipated impact of conformational changes in a novel set of CK2α mutant forms, such as the triple mutant Y206F-R10A-Y261F and the single mutant Y125F
ClickMD: an intuitive web-oriented molecular dynamics platform
No full textBACKGROUND:
Molecular dynamics (MD) simulations are broadly used to reproduce protein motions at an atomic level of detail. Running MD simulations is generally considered an expert-driven task.
DISCUSSION:
ClickMD provides an integrated web-oriented platform for processing and analyzing the time-dependent behavior of a biomolecular system in an MD workflow. ClickMD is freely available online and can be easily integrated into the drug-design process, in particular in combination with molecular docking simulations.
CONCLUSION:
ClickMD has the potential to reduce the shuffling among various software applications and to facilitate the seamless processing of the MD trajectories
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
Development and implementation of a bacterial three-hybrid system for target identification
No full textTarget identification is a crucial step in drug discovery, enabling the development of more effective and safer therapeutic agents. This study focuses on the development and validation of a novel bacterial three-hybrid (B3H) system designed to identify protein targets of small molecules. The system employs SNAP-tag technology to detect interactions between small molecules and their target proteins in Escherichia coli. The use of the Gateway recombination technique streamlined the cloning of fusion proteins and enhanced the system's flexibility. By combining the specificity of affinity methods with the versatility of genetic approaches, the B3H system provides a rapid and cost-effective way to study these interactions. Several tests confirmed the system's effectiveness by evaluating interactions with known targets such as Trypanosoma brucei adenosine kinase, avidin, and dihydrofolate reductase. This work paves the way for future applications in drug target discovery, particularly for bacterial systems.</p
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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