Calorimetría de titulación isotérmica

La unión reversible de un ligando a una proteína o ácido nucleico constituye, con la excepción de los procesos fotoquímicos, el modo universal de iniciación de los procesos biológicos que tienen lugar en los seres vivos (Gutfreund, 1995). El entendimiento de estos procesos de reconocimiento molecular es de fundamental importancia en la biología moderna. Su estudio consiste en determinar la estequiometría, la constante de equilibrio y la energética del proceso. La calorimetría de titulación isotérmica es la única técnica disponible capaz de evaluar a través de un solo experimento estos tres componentes sin ambigüedad. Casi cualquier reacción química o cambio físico producido en un sistema es acompañado por la liberación o absorción de calor. En este sentido los calorímetros pueden ser considerados como detectores universales y a la vez promiscuos, con las ventajas y desventajas que esto implica. A diferencia de los métodos ópticos, las medidas calorimétricas no requieren la incorporación de marcas específicas y se pueden realizar en sistemas opacos, turbios o heterogéneos (por ejemplo, células en suspensión), y bajo una amplia gama de condiciones biológicamente relevantes (temperatura, pH, fuerza iónica, etc.). El primer calorímetro isotérmico fue construido por Lavoiser y Laplace en 1780 (memoria sobre el calor). Desde ese momento se ha desarrollado una amplia variedad de instrumentos, pero no fue hasta 1990 cuando aparecieron en el mercado calorímetros sencillos y con una sensibilidad muy alta, que permitieron estudiar reacciones bioquímicas de asociación. Este tipo de calorímetro, donde se añade un ligando paso a paso a una solución de macromoléculas a temperatura constante y bajo agitación continua, se conoce como calorimetría de titulación isotérmica o ITC por su sigla en inglés (Isothermal Tritation Calorimetry).Facultad de Ciencias Exacta

Los Descendimientos de Erill la Vall y Santa María de Taüll de la colección Plandiura y su relación con el mercado de antigüedades

Este artículo estudia el comercio de antigüedades que surgió alrededor de los grupos del Descendimiento de la cruz de Erill la Vall y Santa María de Taüll durante la primera mitad del siglo XX, y analiza lo que sucedió con cada una de las esculturas que componían ambos conjuntos. Además de considerar el contexto de recuperación de las mismas por parte de los historiadores del arte catalán en 1907, se da a conocer, a través del examen de documentación inédita y de fotografías, cómo llegaron a la colección de Lluís Plandiura las esculturas románicas que actualmente se encuentran en el Museo Nacional de Arte de Cataluña.Aquest article estudia el comerç d'antiguitats que va sorgir al voltant dels grups del Davallament de la creu d'Erill la Vall i Santa Maria de Taüll durant la primera meitat del segle XX, i analitza el que va succeir amb cadascuna de les escultures que componien ambdós conjunts. A més de considerar el context de recuperació d'aquestes per part dels historiadors de l'art català el 1907, es dona a conèixer, a través de l'examen de documentació inèdita i de fotografies, com van arribar a la col·lecció de Lluís Plandiura les escultures romàniques que actualment es troben al Museu Nacional d'Art de Catalunya.This paper explores the antiquities and art trade that emerged in the first half of the 20th century around the iconographic groups of the Deposition from the Cross of Erill la Vall and Santa María de Taüll and analyzes what occurred with each of the sculptures that made up the ensembles. In addition to considering the context in which they were recovered by some Catalonian art historians in 1907, through the analysis of unpublished archival documents and photographs, we show how some of these Romanesque sculptures now housed at the National Art Museum of Catalonia ended up in Lluís Plandiura's collection

Análisis del Impacto Social del Curso de Acceso a La Universidad (GAU) del Plan Integral Pueblo Gitano de La Generalitat de Catalunya

The social and educational situation of the Roma People is clearly alarming: only 1% have managed to finish university studies, while almost 35% of the rest of the population have higher education. Anti-Gypsyism, as well as practices not endorsed by the scientific community, such as educational segregation, explain this situation of exclusion. In this sense, from the Integrated Plan of the Roma People (PIPG) a University Access Group (GAU) is being developed for Roma people over 25 and 45 years of age, based on the Educational Action for Family Training Success. This article collects the results of a study carried out within the framework of a final degree project, aimed to analyze the GAU’s impact and the role of PIPG in the social and educational success of the Roma community. The research has been carried out through a qualitative communication methodology, using documentary analysis and in-depth interviews with key actors. The research suggests that both the PIPG and the GAU are clearly contributing to the educational inclusion of the Roma People, and to overcoming the social exclusion of a large part of this community. These results are fundamental to transform the situation of this community, and especially to improve the effectiveness and efficiency of the social and educational intervention with the Roma People.La situación social y educativa del Pueblo Gitano es claramente alarmante: únicamente un 1% ha conseguido finalizar estudios universitarios, mientras que casi un 35% del resto de la población posee estudios superiores. El Antigitanismo, así como prácticas no avaladas por la comunidad científica, como la segregación educativa, explican esta situación de exclusión. En este sentido, desde el Plan Integral del Pueblo Gitano (PIPG) se está desarrollando un Grupo de Acceso a la Universidad (GAU) para personas gitanas mayores de 25 y 45 años, basado en la Actuación Educativa de Éxito de Formación de Familiares. Este artículo recoge los resultados de un estudio realizado en el marco de un trabajo de final de grado, orientado a analizar el impacto de dicho curso y el papel del PIPG en el éxito social y educativo de la comunidad gitana. La investigación se ha llevado a cabo a través de una metodología comunicativa de corte cualitativo, utilizando análisis documental y entrevistas en profundidad a actores claves. La investigación sugiere que tanto el PIPG como el GAU están contribuyendo de una manera clara a la inclusión educativa del Pueblo Gitano, y a la superación de la exclusión social de gran parte de esta comunidad. Estos resultados se muestran fundamentales para transformar la situación de esta comunidad, y especialmente para mejorar la eficacia y eficiencia de la intervención social y educativa con el Pueblo Gitano

A Discussion on Fall Detection Issues and Its Deployment: When cloud meets battery

IEEE International Conference on Cloud Computing and Big Data Analysis (3rd. 2018., Chengdu, China

Cooperativity in binding processes: New insights from phenomenological modeling

Cooperative binding is one of the most interesting and not fully understood phenomena involved in control and regulation of biological processes. Here we analyze the simplest phenomenological model that can account for cooperativity (i.e. ligand binding to a macromolecule with two binding sites) by generating equilibrium binding isotherms from deterministically simulated binding time courses. We show that the Hill coefficients determined for cooperative binding, provide a good measure of the Gibbs free energy of interaction among binding sites, and that their values are independent of the free energy of association for empty sites. We also conclude that although negative cooperativity and different classes of binding sites cannot be distinguished at equilibrium, they can be kinetically differentiated. This feature highlights the usefulness of pre-equilibrium time-resolved strategies to explore binding models as a key complement of equilibrium experiments. Furthermore, our analysis shows that under conditions of strong negative cooperativity, the existence of some binding sites can be overlooked, and experiments at very high ligand concentrations can be a valuable tool to unmask such sites.Instituto de Física de Líquidos y Sistemas BiológicosFacultad de Ciencias Exacta

Molecular Characterization of the Glycated Plasma Membrane Calcium Pump

We have previously demonstrated (Diabetes 39:707–711, 1990) that in vitro glycation of the red cell Ca2+ pump diminishes the Ca2+-ATPase activity of the enzyme up to 50%. Such effect is due to the reaction of glucose with lysine residues of the Ca2+ pump (Biochem. J. 293:369–375, 1993). The aim of this work was to determine whether the effect of glucose is due to a full inactivation of a fraction of the total population of Ca2+ pump, or to a partial inactivation of all the molecules. Glycation decreased the Vmax; for the ATPase activity leaving unaffected the apparent affinities for Ca2+, calmodulin or ATP. The apparent turnover was identical in both, the glycated and the native enzyme. Glycation decreased the Vmax; for the ATP-dependent but not for the calmodulin-activated phosphatase activities. Concomitantly with the inhibition, up to 6.5% of the lysine residues were randomly glycated. The probabilistic analysis of the relation between the enzyme activity and the fraction of nonmodified residues indicates that only one Lys residue is responsible for the inhibition. We suggest that glucose decreases the Ca2+-ATPase activity by reacting with one essential Lys residue probably located in the vicinity of the catalytic site, which results in the full inactivation of the enzyme. Thus, Ca2+-ATPase activity measured in erythrocyte membranes or purified enzyme preparations preincubated with glucose depends on the remaining enzyme molecules in which the essential Lys residue stays unglycated.Centro de Endocrinología Experimental y Aplicad

Activation of Archaeoglobus fulgidus Cu+-ATPase CopA by cysteine

AbstractCopA, a thermophilic ATPase from Archaeoglobus fulgidus, drives the outward movement of Cu+ across the cell membrane. Millimolar concentration of Cys dramatically increases (≅800%) the activity of CopA and other PIB-type ATPases (Escherichia coli ZntA and Arabidopsis thaliana HMA2). The high affinity of CopA for metal (≅1 μM) together with the low Cu+–Cys KD (<10−10M) suggested a multifaceted interaction of Cys with CopA, perhaps acting as a substitute for the Cu+ chaperone protein present in vivo. To explain the activation by the amino acid and further understand the mechanism of metal delivery to transport ATPases, Cys effects on the turnover and partial reactions of CopA were studied. 2–20 mM Cys accelerates enzyme turnover with little effect on CopA affinity for Cu+, suggesting a metal independent activation. Furthermore, Cys activates the p-nitrophenyl phosphatase activity of CopA, even though this activity is metal independent. Cys accelerates enzyme phosphorylation and the forward dephosphorylation rates yielding higher steady state phosphoenzyme levels. The faster dephosphorylation would explain the higher enzyme turnover in the presence of Cys. The amino acid has no significant effect on low affinity ATP Km suggesting no changes in the E1↔E2 equilibrium. Characterization of Cu+ transport into sealed vesicles indicates that Cys acts on the cytoplasmic side of the enzyme. However, the Cys activation of truncated CopA lacking the N-terminal metal binding domain (N-MBD) indicates that activation by Cys is independent of the regulatory N-MBD. These results suggest that Cys is a non-essential activator of CopA, interacting with the cytoplasmic side of the enzyme while this is in an E1 form. Interestingly, these effects also point out that Cu+ can reach the cytoplasmic opening of the access path into the transmembrane transport sites either as a free metal or a Cu+–Cys complex

Rapid Increases in the Steady-state Concentration of Reactive Oxygen Species in the Lungs and Heart After Particulate Air Pollution Inhalation.

In vitro studies suggest that reactive oxygen species contribute to the cardiopulmonary toxicity of particulate air pollution. To evaluate the ability of particulate air pollution to promote oxidative stress and tissue damage in vivo, we studied a rat model of short-term exposure to concentrated ambient particles (CAPs). We exposed adult Sprague-Dawley rats to either CAPs aerosols (group 1; average CAPs mass concentration, 300 +/- 60 micro g/m3) or filtered air (sham controls) for periods of 1-5 hr. Rats breathing CAPs aerosols for 5 hr showed significant oxidative stress, determined as in situ chemiluminescence in the lung [group 1, 41 +/- 4; sham, 24 +/- 1 counts per second (cps)/cm2] and heart (group 1, 45 +/- 4; sham, 24 +/- 2 cps/cm2) but not liver (group 1, 10 +/- 3; sham, 13 +/- 3 cps/cm2). Increases in oxidant levels were also triggered by highly toxic residual oil fly ash particles (lung chemiluminescence, 90 +/- 10 cps/cm2; heart chemiluminescence, 50 +/- 3 cps/cm2) but not by particle-free air or by inert carbon black aerosols (control particles). Increases in chemiluminescence showed strong associations with the CAPs content of iron, manganese, copper, and zinc in the lung and with Fe, aluminum, silicon, and titanium in the heart. The oxidant stress imposed by 5-hr exposure to CAPs was associated with slight but significant increases in the lung and heart water content (approximately 5% in both tissues, p &lt; 0.05) and with increased serum levels of lactate dehydrogenase (approximately 80%), indicating mild damage to both tissues. Strikingly, CAPs inhalation also led to tissue-specific increases in the activities of the antioxidant enzymes superoxide dismutase and catalase, suggesting that episodes of increased particulate air pollution not only have potential for oxidant injurious effects but may also trigger adaptive responses