Crystal structure of Pisum arvense seed lectin (PAL) and characterization of its interaction with carbohydrates by molecular docking and dynamics.

The Pisum arvense lectin (PAL), a legume protein belonging to the Vicieae tribe, is capable of specific recognition of mannose, glucose and its derivatives without altering its structure. In this work, the three-dimensional structure of PAL was determined by X-ray crystallography and studied in detail by a combination of molecular docking and molecular dynamics (MD). Crystals belonging to monoclinic space group P21 were grown by the vapor diffusion method at 293 K. The structure was solved at 2.16 Å and was similar to that of other Vicieae lectins. The structure presented Rfactor and Rfree of 17.04% and 22.08%, respectively, with all acceptable geometric parameters. Molecular docking was performed to analyze interactions of the lectin with monosaccharides, disaccharides and high-mannose N-glycans. PAL demonstrated different affinities on carbohydrates, depending on bond orientation and glycosidic linkage present in ligands. Furthermore, the lectin interacted with representative N-glycans in a manner consistent with the biological effects described for Vicieae lectins. Carbohydrate-recognition domain (CRD) in-depth analysis was performed by MD, describing the behavior of CRD residues in complex with ligand, stability, flexibility of the protein over time, CRD volume and topology. This is a first report of its kind for a lectin of the Vicieae tribe.

Purification of a thermostable antinociceptive lectin isolated from Andira anthelmia.

Andira anthelmia (tribe Dalbergieae), a plant from Brazilian Amazon, possesses a seed lectin that was purified by affinity chromatography in sepharose-mannose. This novel Dalbergieae lectin, named AAL, agglutinated rabbit erythrocytes treated with trypsin. The hemagglutinating activity of AAL was maintained after incubation at a wide range of temperature (40 to 70 °C) and pH, was shown to be dependent on divalent cations, and was inhibited by d-mannose and d-sucrose. AAL showed an electrophoretic profile in sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to other lectins of the tribe Dalbergieae, presenting a double band of molecular weight with approximately 20 kDa and other minor bands of 17, 15, and 13 kDa, being the smaller fragment glycosylated. AAL injected by intravenous route in mice showed antinociceptive activity in two behavioral tests (writhing and formalin). In the writhing test induced by acetic acid, AAL showed inhibitory effect at 0.01 mg/kg (68%), 0.1 mg/kg (46%) and 1 mg/kg (74%). In the formalin test, AAL (0.1 mg/kg) inhibited by 48% the licking time in the inflammatory phase, an effect that was recovered by the lectin association with mannose. In conclusion, AAL presents analgesic effect involving the lectin domain via peripheral mechanisms of inflammatory nociception. This activity highlights the importance of lectins as tools to be used for understanding the interaction of protein-carbohydrate in processes associated to inflammatory pain. Copyright © 2015 John Wiley & Sons, Ltd.

Impact Of Sars-Cov-2 And Its Reverberation In Global Higher Education And Mental Health.

BACKGROUND: According to UNESCO's monitoring, more than 160 countries implemented nationwide closures, which impacted over 87% of the world's student population. Several other countries implemented localized school closures; should these closures become nationwide, millions of additional learners will experience education disruption. Universities from around the world have been uncertain about how long the coronavirus crisis will last and how it might affect the mental health of students and faculty. The psychological impact has been a critical disruptor, creating anxiety and uncertainty. METHOD: The data were cross-checked with information from the main international newspapers. RESULTS: By discussing online and distance education, the coronavirus opens an important and urgent issue that affects mental health - these are virtually unexplored topics, and their results have not been validated yet. Online education is not limited to distance education, as it regards a grouping of learning/teaching procedures completed in cyberspace. Blended learning was, thus, introduced as a tool in personalized learning to adjust to new realities. These are unprecedented circumstances, and we understand they create stress, favoring anguish and a fierce search for new knowledge acquisition. CONCLUSIONS: Current research highlights that anxiety and depression, exacerbated by uncertainties and intensification of the information flow, will grow extensively. Negative physiological consequences of stress will manifest. For instance, loneliness, which will increase under these circumstances, seems to have a negative impact on education and, therefore, on psychological pain and suffering.

When health professionals look death in the eye: the mental health of professionals who deal daily with the 2019 coronavirus outbreak.

BACKGROUND: The fact that COVID-19 is transmissible from human to human and associated with high morbidity and potentially fatality can intensify the perception of personal danger. In addition, the foreseeable shortage of supplies and an increasing flow of suspected and real cases of COVID-19 contribute to the pressures and concerns of health professionals. METHOD: The studies were identified in well-known international journals found in two electronic databases: Scopus and Embase. The data were cross-checked with information from the main international newspapers. RESULTS: Work-related stress is a potential cause of concern for health professionals. It has been associated with anxiety including multiple clinical activities, depression in the face of the coexistence of countless deaths, long work shifts with the most diverse unknowns and demands in the treatment with patients with COVID-19. Therefore, it is an important indicator of psychic exhaustion. CONCLUSIONS: As coronavirus cases increase and deaths surge in Italy, new figures show an "enormous" level of contagion among the country's medical personnel. At least 2,629 health workers have been infected with coronavirus since the outbreak onset in February, representing 8.3% of total cases. The percentage of infected health workers has almost doubled the number registered in China throughout the epidemic. Intensive care unit physicians are on their stress limit, especially when dealing with older patients and with death prospects. Doctors, not a relative, are inevitably the last people a dying COVID-19 patient will see.

Antibiotic Activity Potentiation and Physicochemical Characterization of the Fixed Orbignya speciosa Almond Oil against MDR Staphylococcus aureus and Other Bacteria.

Orbignya speciosa (babassu) is an important palm tree in Brazil whose fixed almond oil is used in popular medicine and especially in food, in addition to being a research target for the manufacture of biofuels. The aim of this study was to evaluate the fixed almond oil physicochemical characterization and its antibacterial activity in isolation and in association with aminoglycosides against standard and multidrug-resistant bacteria. Analyses such as water content, pH, acidity, peroxide index, relative density, and refractive index indicate the stability and chemical quality of the oil. In the oil's GC/MS chemical composition analysis, a high saturated fatty acid (76.90%) content was observed. Lauric acid (56.28%) and oleic acid (23.10%) were the major oil components. In the antibacterial test, a more significant oil activity was observed against K. pneumoniae KP-ATCC 10031 (minimal inhibitory concentration (MIC) = 406.37 µg/mL) and Staphylococcus aureus ATCC 6538 (MIC = 812.75 µg/mL), but for the other strains-including standard and multi-resistant strains-the oil presented an MIC ≥ 1024 µg/mL. Furthermore, a synergistic effect was observed when the oil was associated with amikacin and gentamicin against S. aureus (SA-10) and an antagonistic effect was observed with amikacin against Escherichia coli. Data indicate the O. speciosa oil as a valuable nutritional source of lauric, oleic, and myristic fatty acids with an ability to modulate aminoglycoside activity.

Crystal structure of Dioclea violacea lectin and a comparative study of vasorelaxant properties with Dioclea rostrata lectin.

Lectins from Diocleinae subtribe belong to the family of legume lectins and are characterized by high identity between their amino acids sequences. It has been shown that punctual differences in amino acid sequences, such as one single amino acid or an alternative conformation, represent changes in biological activities caused by these lectins. Therefore, a more detailed understanding of three-dimensional structures of these proteins is essential for accurate analyzing the relationship between structure and function. In this study lectins purified from the seeds of Dioclea violacea (DVL) and Dioclea rostrata (DRL) were compared with regard to crystal structure and vasorelaxant properties. Differences in structure of lectins were found to be reflected in differences in vasorelaxant effects based on their high specificity and selectivity for cell glycans. Binding activity was related to the position of specific residues in the carbohydrate recognition domain (CRD). DVL complexed structure was solved by X-ray crystallography and was compared to native DVL and DRL. Therefore, DVL was co-crystallized with X-Man, and a molecular modeling with X-Man complexed with DVL was done to compare the complexed and native forms adjusted fit. The relatively narrow and deep CRD in DVL promotes little interaction with carbohydrates; in contrast, the wider and shallower CRD in DRL favors interaction. This seems to explain differences in the level of relaxation induced by DVL (43%) and DRL (96%) in rat aortic rings.

Vascular smooth muscle relaxation by a lectin from Pisum arvense: evidences of endothelial NOS pathway.

The vasorelaxant effect of the lectin of Pisum arvense (PAL) seeds was investigated in rat aorta. PAL (10-100 µg/ml) was applied on aorta rings, with or without endothelium, pre-contracted with phenylephrine (Phe; 0.1 µM). Participation of endothelium derived relaxant factors was evaluated incubating the tissue with indomethacin (10 µM), L-nitro arginine methyl ester (L-NAME, 100 µM) and tetraethylammonium (TEA, 5 mM) before addition of PAL. The role of the lectin domain was investigated by addition of PAL into tissue in presence of glucose (3x 10⁻5 M), or N-acetyl Dglucosamine (GlcNAc; 3 x 10⁻4 M). The importance of extracellular calcium (Ca²âºe) or interaction with muscarinic receptors in the relaxant effect was evaluated by addition of PAL into aorta rings containing calcium free solution (OCa) and atropine (1 µ M), respectively. PAL induced concentration-dependent relaxation in endothelized aorta (IC50 =58.38 ± 1.87 µg/ml), which was reversed by L-NAME and glucose. The lectin effect was totally inhibited when the preparation was inserted in OCa, but not in presence of atropine. Summarizing, our data showed a relaxant effect of PAL in isolated rat aorta rings in presence of endothelium, suggestive of interaction between the lectin carbohydrate binding sites with specific receptors located in vascular endothelial cells leading to nitric oxide synthase activation. This effect seems to require Ca²âºe but is independent on muscarinic receptors interaction.