RMN y reconocimiento molecular:relación estructura-actividad de péptidos implicados en el dolor e interacciones proteína-carbohidrato

El reconocimiento molecular es el punto de partida de numerosos procesos biológicos. La comprensión del reconocimiento entre los ligandos y sus dianas es clave en la optimización y diseño de complejos de mayor afinidad. La combinación de datos de RMN con cálculos teóricos facilita desarrollar una aproximación a la comprensión de las bases moleculares de estos procesos de reconocimiento ligando-receptor. En esta tesis hemos estudiado cuatro sistemas ligando-receptor de interés biológico empleando esta estrategia combinando de RMN y modelización molecular (MM, MD y ab initio). - Estudio estructural de análogos del péptido opiorfina. Opiorfina (QRFSR) es un péptido que impide la degradación de las encefalinas mediante la inhibición de las proteasas NEP y APN. Esta acción sobre el catabolismo de las encefalinas determina un efecto analgésico, demostrado en modelos animales. En este capítulo se han esudiado distintos análogos de la opiorfina cuya actividad ha sido correlacionada con los cambios estructurales observados en RMN. El barrido de alanina en la secuencia de la opiorfina reveló que la sustitución del residuo Phe3 produce una perdida drástica de la actividad frente a NEP y APN. Seguidamente, distintas modificaciones en esta posición mostraron la posibilidad de afectar la selectividad de la capacidad inhibitoria de este péptido. La sustitución de L-Phe por D-Phe mejoró la potencia de la opiorfina frente a APN, perdiendo su actividad frente a NEP. Esta modulación de su actividad se correlaciona con cambios en los espectros de RMN de los péptidos que contienen el enantiómero D-Phe. La diferencia experimental más notable es el apantallamiento de los protones de la Arg2 en los péptidos que contienen D-Phe. Los cálculos de MM mostraron la proximidad espacial entre el anillo aromático y la Arg2, confirmándose el apantallamiento en los espectros RMN. Este estudio muestra una posible interacción catión/ entre la D-Phe3 y la Arg2 que favorece una restricción conformacional que determina una interacción selectiva con APN, mientras que la flexibilidad del péptido natural permite la inhibición dual, pero de menor afinidad frente a APN..

Risk Factors for COVID-19 in Inflammatory Bowel Disease: A National, ENEIDA-Based Case–Control Study (COVID-19-EII)

(1) Scant information is available concerning the characteristics that may favour the acquisition of COVID-19 in patients with inflammatory bowel disease (IBD). Therefore, the aim of this study was to assess these differences between infected and noninfected patients with IBD. (2) This nationwide case-control study evaluated patients with inflammatory bowel disease with COVID-19 (cases) and without COVID-19 (controls) during the period March-July 2020 included in the ENEIDA of GETECCU. (3) A total of 496 cases and 964 controls from 73 Spanish centres were included. No differences were found in the basal characteristics between cases and controls. Cases had higher comorbidity Charlson scores (24% vs. 19%; p = 0.02) and occupational risk (28% vs. 10.5%; p < 0.0001) more frequently than did controls. Lockdown was the only protective measure against COVID-19 (50% vs. 70%; p < 0.0001). No differences were found in the use of systemic steroids, immunosuppressants or biologics between cases and controls. Cases were more often treated with 5-aminosalicylates (42% vs. 34%; p = 0.003). Having a moderate Charlson score (OR: 2.7; 95%CI: 1.3-5.9), occupational risk (OR: 2.9; 95%CI: 1.8-4.4) and the use of 5-aminosalicylates (OR: 1.7; 95%CI: 1.2-2.5) were factors for COVID-19. The strict lockdown was the only protective factor (OR: 0.1; 95%CI: 0.09-0.2). (4) Comorbidities and occupational exposure are the most relevant factors for COVID-19 in patients with IBD. The risk of COVID-19 seems not to be increased by immunosuppressants or biologics, with a potential effect of 5-aminosalicylates, which should be investigated further and interpreted with caution

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

4to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

Este volumen acoge la memoria académica de la Cuarta edición del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2017, desarrollado entre el 29 de noviembre y el 1 de diciembre de 2017 y organizado por la Universidad Politécnica Salesiana (UPS) en su sede de Guayaquil. El Congreso ofreció un espacio para la presentación, difusión e intercambio de importantes investigaciones nacionales e internacionales ante la comunidad universitaria que se dio cita en el encuentro. El uso de herramientas tecnológicas para la gestión de los trabajos de investigación como la plataforma Open Conference Systems y la web de presentación del Congreso http://citis.blog.ups.edu.ec/, hicieron de CITIS 2017 un verdadero referente entre los congresos que se desarrollaron en el país. La preocupación de nuestra Universidad, de presentar espacios que ayuden a generar nuevos y mejores cambios en la dimensión humana y social de nuestro entorno, hace que se persiga en cada edición del evento la presentación de trabajos con calidad creciente en cuanto a su producción científica. Quienes estuvimos al frente de la organización, dejamos plasmado en estas memorias académicas el intenso y prolífico trabajo de los días de realización del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad al alcance de todos y todas

Application of NMR methods to the study of the interaction of natural products with biomolecular receptors

8 páginas, 7 figuras -- PAGS nros. 1118-1125In this review, we present applications of NMR spectroscopy as a potent tool for the study of molecular interactions. It is clear that a variety of NMR methods may be employed to deduce key features of ligand–receptor molecular recognition processes, looking at the process from the perspective of the receptor or the ligand. We have not provided an exhaustive review, but we have tried to focus on describing the different aspects within this research topic. We have therefore selected examples accordingly, depending on the particular problem under study or the application/development of protocols to circumvent the technical problems that may be found when working in this fieldWe thank the Ministry of Science and Innovation of Spain for financial support (Grant CTQ2009-08536) and all the colleagues that have collaborated with us over yearsPeer reviewe

Characterization of exopolysaccharides produced by Bifidobacterium longum NB667 and Its cholate-resistant derivative strain IPLA B667dCo

Bifidobacteria are natural members of the human intestinal microbiota and some strains are being used as probiotics. Adaptation to bile can allow them to increase survival in gastrointestinal conditions, thus improving their viability. Bifidobacterium longum NB667 and the cholate-resistant strain B. longum IPLA B667dCo produced exopolysaccharides (EPS) that were partially characterized. Analysis by size exclusion chromatography-multiangle laser light scattering indicated that the EPS crude fractions of both strains contained two polymer peaks of different molar mass. On the basis of chromatographic techniques both peaks appeared to be heteropolysaccharides. The smaller peak was mainly composed of glucose, galactose and rhamnose whose molar ratios and linkage types showed slight variations between the EPS fractions of both strains. The bigger peak consisted of glucose and galactose; the monosaccharide composition was identical in the EPS fractions of the two microorganisms, but their infrared spectra presented some differences regarding compounds other than carbohydrates that seem to be associated to the polymer. Differences in the composition of EPS fractions did not affect the capability of crude EPS from B. longum to be fermented by the human intestinal microbiota in fecal batch cultures. © 2012 American Chemical Society.This work was financially supported by the European Union FEDER funds and by the Plan Nacional de I + D under projects AGL2004-6088, AGL2007-62736, and AGL2010-16525.Peer Reviewe

NMR characterization of differential binding of sugar anomers by lectins

1 p.Reducing carbohydrates can be characterized in two different structures depending of the configuration at the anomeric position of the reducing end. Anomeric selectivity has been observed and studied in enzymes involved in carbohydrate transformations by diverse kinetic approaches since long time ago1, however those approaches are not possible in the case of just binding studies of carbohydrate in solution. Lectins and other carbohydrates receptors do not modified their ligands, thus do not generate time dependent responses feasible of monitoring. Taking into account that free anomers equilibrate in no more than a few hours, many of the available biophysical techniques in solution only provide a mean macroscopic view of the recognition event involving the mixture of anomers in equilibrium. The direct discrimination of the recognition of each anomer is not an easy task, and NMR can be technique of choice because it allows observing independent signals for each anomer in spite of they are in chemical equilibrium exchange. In fact, 13C NMR has been used to show the - anomer preference of bacterial chemotaxis sugar binding proteins 2 and more exotic tritium 3H -NMR has been used to study anomeric preference in maltose binding protein 3. In the present work we have applied STD–NMR strategies, to obtain quantitative information on the individual interaction of each anomer, combined with molecular modeling in order to characterize the differential monosaccharide anomer affinity by some selected lectins.Peer reviewe

Structure-activity relationship study of opiorphin, a human dual ectopeptidase inhibitor with antinociceptive properties

8 páginas, 4 figuras, 3 tablas, 1 esquema -- PAGS nros. 1181-1188Toward developing new potential analgesics, this first structure–activity relationship study of opiorphin (H-Gln-Arg-Phe-Ser-Arg-OH), a human peptide inhibiting enkephalin degradation, was performed. A systematic Ala scanning proved that Phe3 is a key residue for neprilysin and aminopeptidase N (AP-N) ectoenkephalinase inhibition. A series of Phe3-halogenated analogues revealed that halogen bonding based optimization strategies are not applicable to this residue. Additional substituted Phe3 derivatives showed that replacing l-Phe3 for d-Phe3 increased the AP-N inhibition potency by 1 order of magnitude. NMR studies and molecular mechanics calculations indicated that the improved potency may be due to CH−π stacking interactions between the aromatic ring of d-Phe3 and the Hγ protons of Arg2. This structural motif is not possible for the native opiorphin and may be useful for the design of further potent and metabolically stable analoguesThis work was supported by a grant from the Fundació Marató de TV3 (Pain, Project Reference 070430-31-32-33). We thank F. J. Cañada for helpful discussions. J.J.-B. acknowledges financial support from the Ministerio de Ciencia e Innovación (Spain) (Grant CTQ2009-08536). F.M. thanks FCT-Portugal for a postdoctoral research grant (SFRH/BPD/65462/2009). M.R. acknowledges a fellowship (Grant AP2009-2534, Formación de Profesorado Universitario) from the Ministry of EducationPeer reviewe

New Cathepsin Inhibitors to Explore the Fluorophilic Properties of the S2 Pocket of Cathepsin B: Design, Synthesis, and Biological Evaluation

5 páginas, 1 figura, 2 tablas -- PAGS nros. 5256-5260Fluor-in or out? Based on β,β-difluorinated cycloaliphatic amino acids, a library of new dipeptide nitriles was evaluated as human cathepsin inhibitors. The orientation of the fluorinated face relative to the protein structure of cathepsin B was elucidated by molecular modeling and NMR studies (see figure). For (R)-configured eutomers, the fluorine atoms are directed to the S2 pocket, whereas in (S)-configured distomers, the fluorinated face is solvent-exposedThis work was supported by a grant from the Ministry of Science and Innovation of Spain (CTQ2007-61462/BQU, CTQ2006-10874-C02-01/BQU, CTQ2009-08536, CTQ2010-19774-C02, and GV/PROMETEO/2010/061). V.R. expresses their thanks for a predoctoral fellowship. C.d.P. and M.S.R thank the same institution for a Ramón y Cajal and a Juan de la Cierva contract, respectively. M.F. is supported by a fellowship from the NRW Forschungsschule Biotech-Pharma, and M.T.S. by a fellowship from the Graduiertenkolleg (GRK) 677 of the Deutsche ForschungsgemeinschaftPeer reviewe

Synthesis, biological evaluation and structural characterization of novel glycopeptide analogues of nociceptin N/OFQ

10 páginas, 6 figuras, 1 tabla -- PAGS nros. 6133-6142To examine if the biological activity of the N/OFQ peptide, which is the native ligand of the pain-related and viable drug target NOP receptor, could be modulated by glycosylation and if such effects could be conformationally related, we have synthesized three N/OFQ glycopeptide analogues, namely: [Thr5-O-α-D-GalNAc-N/OFQ] (glycopeptide 1), [Ser10-O-α-D-GalNAc]-N/OFQ (glycopeptide 2) and [Ser10-O-β-D-GlcNAc]-N/OFQ] (glycopeptide 3). They were tested for biological activity in competition binding assays using the zebrafish animal model in which glycopeptide 2 exhibited a slightly improved binding affinity, whereas glycopeptide 1 showed a remarkably reduced binding affinity compared to the parent compound and glycopeptide 3. The structural analysis of these glycopeptides and the parent N/OFQ peptide by NMR and circular dichroism indicated that their aqueous solutions are mainly populated by random coil conformers. However, in membrane mimic environments a certain proportion of the molecules of all these peptides exist as α-helix structures. Interestingly, under these experimental conditions, glycopeptide 1 (glycosylated at Thr-5) exhibited a population of folded hairpin-like geometries. From these facts it is tempting to speculate that nociceptin analogues showing linear helical structures are more complementary and thus interact more efficiently with the native NOP receptor than folded structures, since glycopeptide 1 showed a significantly reduced binding affinity for the NOP receptorThe work was supported by a grant from the Fundació Marató de TV3 (Pain, project reference 070430-31-32-33). We thank F. J Cañada, M. Morando and L. Nieto for helpful discussions, and M. Bruix for the access to the 800 MHz NMR spectrometer. JJB acknowledges Ministerio de Ciencia e Innovación (Spain) (CTQ2009-08536) for financial support. F. M. thanks to FCT-Portugal for a post-doc research grant (SFRH/BPD/65462/2009). JTV acknowledges Ministerio de Ciencia e Innovación (Spain) (CTQ2007-67532-C02-02/BQU) for financial support. M. R. acknowledges a fellowship (AP2009-2534, Formación de Profesorado Universitario) from the Ministry of EducationPeer reviewe