Changing employment: Receptor 1 binds β‐N‐acetylglucosaminyl (β‐GlcNAc) up to 100 times more strongly than it does glucose. This synthetic lectin shows affinities similar to wheat germ agglutinin (WGA), a natural lectin used to bind GlcNAc. Remarkably, 1 is more selective than WGA. It favors especially the glycoside unit in glycopeptide 2, a model of the serine‐O‐GlcNAc posttranslational protein modification.

A sweet center: Most carbohydrates are supremely comfortable in water. Can they be tempted to leave? Yes, if their new home satisfies all their needs. The water‐soluble receptor 1 (R=polycarboxylate) provides hydrophobic surfaces (purple) for CH groups and amide groups (red) for polar substituents. Equatorial substitution is especially well accommodated, and the system duly favors β‐glucosyl (2).

Ein süßes Zentrum: Die meisten Kohlenhydrate fühlen sich in Wasser sehr wohl. Können sie überredet werden, es zu verlassen? Ja, wenn ihr neues Zuhause alle ihre Bedürfnisse befriedigt. Der wasserlösliche Rezeptor 1 (R=Polycarboxylat) bietet hydrophobe Oberflächen (blauviolett) für CH‐Gruppen und Amidgruppen (rot) für polare Substituenten. Äquatorialsubstitution ist besonders willkommen, und das System zieht entsprechend β‐Glucosyl (2) vor.

Carbohydrate recognition is a key natural phenomenon [1] that mediates protein trafficking [1g] and function, [1h] cell-cell recognition and adhesion, [1i,j] and many aspects of the immune response. Despite its importance, it is not well understood in all respects. In particular, the driving force for saccharide binding by lectins and other carbohydrate-binding proteins is subject to debate.[2] The discussion centers on the part played by water. Crystal structures of protein-carbohydrate complexes reveal dense networks of intermolecular hydrogen bonds, but these bonds can only form after desolvation of the binding surfaces. Complex formation [Eq. (1)] involves the interchange of carbohydrate-OH groups with H 2 O molecules, which is not an obviously favorable process.

No abstract

Stay flexible: Rigid preorganization is not always the best approach to molecular recognition. Unlike previous synthetic lectins, new receptors (see picture) were synthesized that possess conformational freedom which allows hydrophobically driven collapse of the cavity. Nonetheless, they bind their carbohydrate targets in water with ground‐breaking affinities (up to 4500 M−1 for methyl cellobioside, R=Me) and selectivities.

No abstract

Although a great number of cationic lipids have been designed and evaluated as gene delivery systems, there is still a need for improvement of nonviral vectors. Recently, cationic lipids incorporating terminal fluoroalkyl segments ("FHP" lipids) have been described to display remarkable transfection potency. Here, we describe the synthesis of a new family of fluorinated triblock cationic lipids in which a fluorous segment lays between the cationic and the lipophilic parts of the molecule ("HFP" lipids). The compounds were designed so their self-assembly would offer enhanced resistance toward the host's degradation mechanisms mediated by lipophilic insertion. Self-assembly properties of these cationic lipids were evaluated at the air-water interface where they collapse in a highly ordered liquid phase. The HFP lipids efficiently condense DNA, and the resulting lipoplexes display enhanced resistance to amphiphilic agents when compared to nonfluorinated or FHP cationic lipids. Transfection properties of the fluorinated vectors, alone or as mixtures with different helper lipids (DOPE and a fluorinated analogue of DOPE), were then investigated on different cell lines (BHK-21, HepG2, and HeLa) and compared to those of the reference cationic lipid DOTAP. Data show that impermeabilization of the lipidic phase by fluorous segments alter significantly the gene transfection activities. Remarkably, incorporation of DOPE within the lipoplexes provides the particles with high gene transfection activity without reducing their resistance to amphiphilic agents.