6988-39-2Relevant articles and documents
Exploration of the Fluoride Reactivity of Aryltrifluoroborate on Selective Cleavage of Diphenylmethylsilyl Groups
Fujiki, Katsumasa,Tanaka, Katsunori
supporting information, p. 4616 - 4620 (2020/07/06)
The first known report on the fluoride catalytic reactivity of potassium aryltrifluoroborate is described. The fluoride reactivity of phenyltrifluoroborate was controlled by substituents on the trifluoroborate-attached benzene, such as the methoxy group a
Conformational analysis of the disaccharide methyl a-d-mannopyranosyl-(1→3)-2-O-acetyl-β-D-manno-pyranoside monohydrate
Zhang, Wenhui,Wu, Qingquan,Oliver, Allen G.,Serianni, Anthony S.
, p. 610 - 615 (2019/06/14)
The crystal structure of methyl β-d-mannopyranosyl-(1→3)-2-O-acetyl-β-d-mannopyranoside monohydrate, C15H26O12.H2O, (II), has been determined and the structural parameters for its constituent β-d-mannopyranosyl residue compared with those for methyl β-d-mannopyranoside. Mono-O-acetylation appears to promote the crystallization of (II), inferred from the difficulty in crystallizing methyl β-d-mannopyranosyl-(1→3)-β-d-mannopyranoside despite repeated attempts. The conformational properties of the O-acetyl side chain in (II) are similar to those observed in recent studies of peracetylated mannose-containing oligosaccharides, having a preferred geometry in which the C2—H2 bond eclipses the C O bond of the acetyl group. The C2—O2 bond in (II) elongates by ≈0.02 ? upon O-acetylation. The phi (φ) and psi () torsion angles that dictate the conformation of the internal O-glycosidic linkage in (II) are similar to those determined recently in aqueous solution by NMR spectroscopy for unacetylated (II) using the statistical program MA'AT, with a greater disparity found for (? = ≈16°) than for φ (? = ≈6°).
Binding of the Bacterial Adhesin FimH to Its Natural, Multivalent High-Mannose Type Glycan Targets
Sauer, Maximilian M.,Jakob, Roman P.,Luber, Thomas,Canonica, Fabia,Navarra, Giulio,Ernst, Beat,Unverzagt, Carlo,Maier, Timm,Glockshuber, Rudi
supporting information, p. 936 - 944 (2019/01/11)
Multivalent carbohydrate-lectin interactions at host-pathogen interfaces play a crucial role in the establishment of infections. Although competitive antagonists that prevent pathogen adhesion are promising antimicrobial drugs, the molecular mechanisms underlying these complex adhesion processes are still poorly understood. Here, we characterize the interactions between the fimbrial adhesin FimH from uropathogenic Escherichia coli strains and its natural high-mannose type N-glycan binding epitopes on uroepithelial glycoproteins. Crystal structures and a detailed kinetic characterization of ligand-binding and dissociation revealed that the binding pocket of FimH evolved such that it recognizes the terminal α(1-2)-, α(1-3)-, and α(1-6)-linked mannosides of natural high-mannose type N-glycans with similar affinity. We demonstrate that the 2000-fold higher affinity of the domain-separated state of FimH compared to its domain-associated state is ligand-independent and consistent with a thermodynamic cycle in which ligand-binding shifts the association equilibrium between the FimH lectin and the FimH pilin domain. Moreover, we show that a single N-glycan can bind up to three molecules of FimH, albeit with negative cooperativity, so that a molar excess of accessible N-glycans over FimH on the cell surface favors monovalent FimH binding. Our data provide pivotal insights into the adhesion properties of uropathogenic Escherichia coli strains to their target receptors and a solid basis for the development of effective FimH antagonists.
