1,721,086 research outputs found
Ensembles from Ordered and Disordered Proteins Reveal Similar Structural Constraints during Evolution
Full text linkThe conformations accessible to proteins are determined by the inter-residue interactions between amino acid residues. During evolution, structural constraints that are required for protein function providing biologically relevant information can exist. Here, we studied the proportion of sites evolving under structural constraints in two very different types of ensembles, those coming from ordered and disordered proteins. Using a structurally constrained model of protein evolution, we found that both types of ensembles show comparable, near 40%, number of positions evolving under structural constraints. Among these sites, ~ 68% are in disordered regions and ~ 57% of them show long-range inter-residue contacts. Also, we found that disordered ensembles are redundant in reference to their structurally constrained evolutionary information and could be described on average with ~ 11 conformers. Despite the different complexity of the studied ensembles and proteins, the similar constraints reveal a comparable level of selective pressure to maintain their biological functions. These results highlight the importance of the evolutionary information to recover meaningful biological information to further characterize conformational ensembles.Fil: Marchetti, Julia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Monzón, Alexander. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Università di Padova; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tosatto, Silvio C.E.. Università di Padova; ItaliaFil: Parisi, Gustavo Daniel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fornasari, Maria Silvina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Evaluating the effect of mutations and ligand binding on transthyretin homotetramer dynamics
Full text linkNative transthyretin (TTR) homotetramer dissociation is the first step of the fibrils formation process in amyloid disease. A large number of specific point mutations that destabilize TTR quaternary structure have shown pro-amyloidogenic effects. Besides, several compounds have been proposed as drugs in the therapy of TTR amyloidosis due to their TTR tetramer binding affinities, and therefore, contribution to its integrity. In the present paper we have explored key positions sustaining TTR tetramer dynamical stability. We have identified positions whose mutations alter the most the TTR tetramer equilibrium dynamics based on normal mode analysis and their response to local perturbations. We have found that these positions are mostly localized at β-strands E and F and EF-loop. The monomer-monomer interface is pointed out as one of the most vulnerable regions to mutations that lead to significant changes in the TTR-tetramer equilibrium dynamics and, therefore, induces TTR amyloidosis.Besides, we have found that mutations on residues localized at the dimer-dimerinterface and/or at the T4 hormone binding site destabilize the tetramer more than the average.Finally, we were able to compare several compounds according to their effect on vibrationsassociated to the ligand binding. Our ligand comparison is discussed and analyzed interms of parameters and measurements associated to TTR-ligand binding affinities and thestabilization of its native state.Fil: Saldaño, Tadeo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Zanotti, Giuseppe. Università di Padova; ItaliaFil: Parisi, Gustavo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Fernández Alberti, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentin
Disorder transitions and conformational diversity cooperatively modulate biological function in proteins
Full text linkStructural differences between conformers sustain protein biological function. Here, we studied in a large dataset of 745 intrinsically disordered proteins, how ordered-disordered transitions modulate structural differences between conformers as derived from crystallographic data. We found that almost 50% of the proteins studied show no transitions and have low conformational diversity while the rest show transitions and a higher conformational diversity. In this last subset, 60% of the proteins become more ordered after ligand binding, while 40% more disordered. As protein conformational diversity is inherently connected with protein function our analysis suggests differences in structure-function relationships related to order-disorder transitions.Fil: Zea, Diego Javier. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Monzón, Alexander. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gonzalez, Claudia. Universidad Nacional de Quilmes; ArgentinaFil: Fornasari, Maria Silvina. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tosatto, Silvio C. E.. Università di Padova; ItaliaFil: Parisi, Gustavo Daniel. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
De “las cosas como son” a “sentir orgullo” : un análisis de las representaciones de género y diversidad sexual en las publicidades de Sprite en Argentina
No full textEl objetivo general de mi tesina consiste en hacer una aproximación a las representaciones de género y sexualidad en el discurso publicitario de Sprite en una época determinada. Mi tesina se inserta en el campo de las ciencias sociales con foco en la comunicación y la cultura. Responde al género ensayístico y el interés nace, por un lado, por los constantes cambios en materia de género y diversidades que se han experimentado a nivel social y cultural a lo largo de los últimos años, producto de las demandas colectivas de grupos cuyos derechos se han visto ignorados. Y, por otro lado, por la intención de comprender las formas en que el discurso publicitario reproduce las perspectivas de género y diversidad sexual en cada época, aproximándose a las construcciones y los cambios que se fueron dando en los procesos de conformación de las subjetividades de hombres y mujeres.\n
Para ello busco dar respuesta a los siguientes interrogantes:\n1. ¿Cómo son los modos de ser en que se comportan los hombres y las mujeres en las publicidades de Sprite?\n2. ¿Cuáles son las formas corporales adecuadas para cada uno de los sexos?\n3. ¿Qué tipo de lazos pueden establecer con pares del mismo sexo y con personas de otro sexo?\n4. ¿Cómo se producen los desplazamientos en torno a estos estereotipos?\n
A partir de la siguiente selección de publicidades de Sprite se analizarán estos aspectos. Las publicidades elegidas son: De lejos están todas buenas (2008), Suplentes (2011), ¿Para qué te cuidas? (2010), Escote vence amistad (2011), Las mujeres lloran por todo (2012) correspondientes a la campaña Las cosas como son, hasta la publicidad Orgullo (2019) de la campaña No estás solx.Fil: Parisi, Gustavo. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Buenos Aires, Argentin
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
Evolutionary Analysis of -Carbonic Anhydrase and Structurally Related Proteins
No full textWe studied the evolutionary relationships between γ-carbonic anhydrase (γ-CA) and a very diverse group of proteins that share the sequence motif characteristic of the left-handed parallel β-helix (LβH) fold. This sequence motif is characterized by the imperfect tandem repetition of short hexapeptide units, which makes it difficult to obtain a reliable alignment based on sequence information alone. To solve this problem, we used a structural alignment of three members of the group with known crystallographic structures as a seed to obtain a reliable sequence alignment. Then, we applied protein maximum-parsimony and maximum-likelihood phylogenetic inference methods to this alignment. We found that γ-CA belongs to a diverse superfamily of proteins that share the LβH domain. This superfamily is composed mainly of acyltransferases. The most remarkable feature of the phylogenetic tree obtained is that its main branches group together functionally related proteins, so that the coarse topology can be rather easily explained in terms of functional diversification. Regarding the main branch of the tree containing γ-CA, we found that, in addition to the group of its closest relatives that had already been studied, γ-CA is closely related to the tetrahydrodipicolinate N-succinyltransferases. (C) 2000 Academic Press.Fil: Parisi, Gustavo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Fornasari, Maria Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Echave, Julián. Universidad Nacional de Quilmes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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
- …
