Remodeling of the Oligosaccharide Conformational Space in the Prebound State To Improve Lectin-Binding Affinity.

We developed an approach to improve the lectin-binding affinity of an oligosaccharide by remodeling its conformational space in the precomplexed state. To develop this approach, we used a Lewis X-containing oligosaccharide interacting with RSL as a model system. Using an experimentally validated molecular dynamics simulation, we designed a Lewis X analogue with an increased population of conformational species that were originally very minor but exclusively accessible to the target lectin without steric hindrance by modifying the nonreducing terminal galactose, which does not directly contact the lectin in the complex.

Lewis X-Carrying Neoglycolipids Evoke Selective Apoptosis in Neural Stem Cells.

N-glycans carrying the Lewis X trisaccharide [Galβ1-4 (Fucα1-3) GlcNAc] are expressed by neural stem cells (NSCs) exclusively before differentiation, and they actively contribute to the maintenance of stemness of these cells. To address the functional roles of the Lewis X-mediated molecular interactions in NSCs, we created a series of synthetic neoglycolipids that contained a Lewis X-carrying glycan connected to an acyl chain through an amide bond. The neoglycolipids formed aqueous micelles displaying functional Lewis X glycotopes.

Hyper-Assembly of Self-Assembled Glycoclusters Mediated by Specific Carbohydrate-Carbohydrate Interactions.

Hybridization of a self-assembled, spherical complex with oligosaccharides containing Lewis X, a functional trisaccharide displayed on various cell surfaces, yielded well-defined glycoclusters. The self-assembled glycoclusters exhibited homophilic hyper-assembly in aqueous solution in a Ca -dependent manner through specific carbohydrate-carbohydrate interactions, offering a structural scaffold for functional biomimetic systems.

Structural basis for two-step glucose trimming by glucosidase II involved in ER glycoprotein quality control.

The endoplasmic reticulum (ER) has a sophisticated protein quality control system for the efficient folding of newly synthesized proteins. In this system, a variety of N-linked oligosaccharides displayed on proteins serve as signals recognized by series of intracellular lectins. Glucosidase II catalyzes two-step hydrolysis at α1,3-linked glucose-glucose and glucose-mannose residues of high-mannose-type glycans to generate a quality control protein tag that is transiently expressed on glycoproteins and recognized by ER chaperones.

Influence of the water content on the diffusion coefficients of Li+ and water across naphthalenic based copolyimide cation-exchange membranes.

The transport of lithium ions in cation-exchange membranes based on sulfonated copolyimide membranes is reported. Diffusion coefficients of lithium are estimated as a function of the water content in membranes by using pulsed field gradient (PFG) NMR and electrical conductivity techniques. It is found that the lithium transport slightly decreases with the diminution of water for membranes with water content lying in the range 14 < λ < 26.