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A lectin with strong cytotoxic effect on human colon cancer HT29 and monkey kidney VERO cells was recently identified from the Australian indigenous mushroom Psathyrella asperospora and named PAL. We herein present its biochemical and structural analysis using a multidisciplinary approach. Glycan arrays revealed binding preference towards N-acetylglucosamine (GlcNAc) and, to a lesser extent, towards sialic acid (Neu5Ac). Submicromolar and millimolar affinity was measured by surface plasmon resonance for GlcNAc and NeuAc, respectively. The structure of PAL was resolved by X-ray crystallography, elucidating both the protein's amino acid sequence as well as the molecular basis rationalizing its binding specificity. Proteins 2017; 85:969-975. © 2016 Wiley Periodicals, Inc.

11 páginas, 4 figurasd, 2 esquemas -- PAGS nros. 4354-4364, Our recent description of pulse sequences for the intramolecular relay of 1H polarization to the 19F reporter of a carbohydrate ligand after saturation transfer from a cognate lectin prompted us to test the applicability of this technique for inhibitor screening. By strategically combining synthetic organic chemistry and cell assays with 19F-NMR-based competition experiments, we document the validity of this approach. Two mannose-specific leguminous agglutinins as receptors, the α-methyl derivative of 2-deoxy-2-fluoro-D-mannopyranoside as sensor and synthetic mannosides selected to represent different inhibitory capacities were used to establish a test panel. Signal amplitudes were found to vary among the two related lectins, and their precipitation by glycodendrimers enabled inherent limits to be set. The obtained experimental basis was then broadened by assaying a galactopyranoside-binding plant toxin, using 6-deoxy-6-fluoro-D-galactopyranose as a sensor molecule. The easy identification of the two anomeric signals by 19F NMR spectroscopy enabled ready detection of the preference of this lectin for the α-anomer and allowed the two individual inhibition profiles to be deduced. These 19F NMR spectroscopic data were in accord with the activities of inhibitors used to protect cells from toxicity. Our results therefore provide an experimental basis for 19F-NMR-based inhibitor screening, This work was generously supported by the European Community (Marie Curie Research training grant MCRTN-CT-2005–19561), the Ministerio de Ciencia e Innovación (MICINN) (grant numbers CTQ2009-08536 and BFU2009-10052), and the Spanish Institute of Health Carlos III (ISCIII), under the initiative CIBER of Respiratory Diseases (CIBERES). The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number 260600 (“GlycoHIT”)

This thesis deals with the design, formation and evaluation of dynamic systems constructed by means of sulfur-containing reversible reactions, in organic and aqueous media and under mild conditions. In a first part, the synthesis of thioglycoside derivatives, constituting the biologically relevant starting components of the dynamic systems, is described. In addition, the pD-profile of the mutarotation process in aqueous media for a series of 1-thioaldoses is reported and revealed an astonishing beta-anomeric preference for all the carbohydrate analogs under acidic or neutral conditions. In a second part, the phosphine-catalyzed or -mediated disulfide metathesis for dynamic system generation in organic or aqueous media is presented, respectively. The direct in situ 1H STD-NMR resolution of a dynamic carbohydrate system in the presence of a target protein (Concanavalin A) proved the suitability and compatibility of such disulfide metathesis protocols for the discovery of biologically relevant ligands. In a third part, hemithioacetal formation is demonstrated as a new and efficient reversible reaction for the spontaneous generation of a dynamic system, despite a virtual character of the component associations in basic aqueous media. The direct in situ 1H STD-NMR identification of the best dynamic beta-galactosidase inhibitors from the dynamic HTA system was performed and the results were confirmed by inhibition studies. Thus, the HTA product formed from the reaction between 1-thiogalactopyranose and a pyridine carboxaldehyde derivative provided the best dynamic inhibitor. In a fourth and final part, a dynamic drug design strategy, where the best inhibitors from the aforementioned dynamic HTA system were used as model for the design of non-dynamic (or “static”) beta-galactosidase inhibitors, is depicted. Inhibition studies disclosed potent leads among the set of ligands.

8 páginas, 8 figuras, 1 tabla -- PAGS nros. 5891-5898, A combined NMR, computational, and HPLC study of the inclusion of aromatic and fluoroaromatic compounds in cyclodextrins has been carried out with the aim of studying this process as a model for carbohydrate···aromatic interactions. NMR experiments showed that although β-CD formed an inclusion complex with benzene, no stable inclusion adduct was formed with hexafluorobenzene. MM3* calculations confirmed these data and, when extended to naphthalene, anthracene, phenanthrene, and their partially and fully fluorinated analogues, showed that β-CD formed inclusion adducts only with the hydrocarbons, whereas the partially fluorinated derivatives were shown to enter the cavity only with their non-fluorinated part, and the perfluoro compounds were not included. HPLC experiments, carried out by eluting these compounds through CD-modified HPLC columns, also confirmed these results, at least with the mono- and bicyclic arenes. Indeed, the elution of these derivatives showed that the efficiency of the inclusion, as determined by comparing HPLC retention times, decreased on passing from hydrocarbons to partially fluorinated compounds, and reached a minimum with perfluorinated derivatives. In contrast with this general trend, 1,2,3,4-tetrafluoroanthracene had longer retentions times on β- and γ-CD-modified HPLC columns than anthracene, possibly for solubility reasons. As a whole, these results were interpreted in terms of carbohydrate···aromatic interactions between the C5–H5 bonds on the hydrophobic faces of the sugars and the π electrons of the aromatic partner. The interactions seem to have an important dispersive component.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008), We thank the Spanish Ministerio de Educación y Ciencia (MEC) (grant CTQ-2006-10335) and the European Union (grant MRTN-CT2006-035546) for financial support

3 páginas, 2 figuras -- PAGS nros. 5666-5668, As a novel approach for studying carbohydrate-lectin interactions spectroscopically, we combine the resolution and specificity of (19)F-detected NMR spectroscopy with the sensitivity of the saturation transfer difference (STD) technique. The resulting background-free (19)F-STD spectra open a promising perspective for broad application with medical relevance, for example, in drug discovery, Financial support by a bizkaia: Xede grant, an EC Marie Curie Research Training network (MRTN-CT2005-019561), the Ministry of Science and Innovation of Spain (CTQ2006- 10874-C02-01)