Multivalent interactions can be applied universally for a targeted strengthening of an interaction between different interfaces or molecules. The binding partners form cooperative, multiple receptor-ligand interactions that are based on individually weak, noncovalent bonds and are thus generally reversible. Hence, multi- and polyvalent interactions play a decisive role in biological systems for recognition, adhesion, and signal processes. The scientific and practical realization of this principle will be demonstrated by the development of simple artificial and theoretical models, from natural systems to functional, application-oriented systems. In a systematic review of scaffold architectures, the underlying effects and control options will be demonstrated, and suggestions will be given for designing effective multivalent binding systems, as well as for polyvalent therapeutics.

Multivalency as a chemical organization and action principle.

The orderly migration of various white blood cell types to inflammatory sites is a highly regulated process that involves a diversity of adhesion and signaling molecules. This cellular influx is initiated by relatively low affinity interactions that allow for leukocytes to roll along the vascular surfa ce. This rolling phe­ nomenon is mediated by adhesive interactions between lectin containing ad­ hesion molecules, termed selectins, on both the vascular endothelium and leukocytes, and car bohydrate ligands immobilized on mucin-like scaffolds. This adhesion allows for a rapid recognition of various cell types under the conditions of vascular flow, with the result that inflammatory cells are spe­

Interactions and the initiation of the inflammatory response

The recognition of saccharides by proteins has far reaching implications in biology, technology, and drug design. Within the past two decades, researchers have directed considerable effort toward a detailed understanding of these processes. Early crystallographic studies revealed, not surprisingly, that hydrogen-bonding interactions are usually involved in carbohydrate recognition. But less expectedly, researchers observed that despite the highly hydrophilic character of most sugars, aromatic rings of the receptor often play an important role in carbohydrate recognition.With further research, scientists now accept that noncovalent interactions mediated by aromatic rings are pivotal to sugar binding. For example, aromatic residues often stack against the faces of sugar pyranose rings in complexes between proteins and carbohydrates. Such contacts typically involve two or three CH groups of the pyranoses and the π electron density of the aromatic ring (called CH/π bonds), and these interactions can exhibit a...

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Carbohydrate–Aromatic Interactions

Synthesis of glycopolymers and their multivalent recognitions with lectins

Multivalent carbohydrates are currently produced in many forms ranging from dendrimers, polymers, micelles, vesicles, nanoparticles to functionalized nanotubes, in order to enhance the potency of the carbohydrates as ligands or inhibitors. Variations in valency range from systems containing two carbohydrate units to those containing more than 2000. In this perspective a number of popular target proteins for multivalent binding/inhibition have been selected. The optimal systems displaying the largest multivalency effects are discussed with respect to their mechanism of multivalent binding.

Maximising multivalency effects in protein–carbohydrate interactions

The inhibition of carbohydrate-protein interactions by tailored multivalent ligands is a powerful strategy for the treatment of many human diseases. Crucial for the success of this approach is an understanding of the molecular mechanisms as to how a binding enhancement of a multivalent ligand is achieved. We have synthesized a series of multivalent N-acetylglucosamine (GlcNAc) derivatives and studied their interaction with the plant lectin wheat germ agglutinin (WGA) by an enzyme-linked lectin assay (ELLA) and X-ray crystallography. The solution conformation of one ligand was determined by NMR spectroscopy. Employing a GlcNAc carbamate motif with alpha-configuration and by systematic variation of the spacer length, we were able to identify divalent ligands with unprecedented high WGA binding potency. The best divalent ligand has an IC(50) value of 9.8 microM (ELLA) corresponding to a relative potency of 2350 (1170 on a valency-corrected basis, i.e., per mol sugar contained) compared to free GlcNAc. X-ray crystallography of the complex of WGA and the second best, closely related divalent ligand explains this activity. Four divalent molecules simultaneously bind to WGA with each ligand bridging adjacent binding sites. This shows for the first time that all eight sugar binding sites of the WGA dimer are simultaneously functional. We also report a tetravalent neoglycopeptide with an IC(50) value of 0.9 microM being 25,500 times higher than that of GlcNAc (6400 times per contained sugar) and the X-ray structure analysis of its complex with glutaraldehyde-cross-linked WGA. Comparison of the crystal structure and the solution NMR structure of the neoglycopeptide as well as results from the ELLA suggest that the conformation of the glycopeptide in solution is already preorganized in a way supporting multivalent binding to the protein. Our findings show that bridging adjacent protein binding sites by multivalent ligands is a valid strategy to find high-affinity protein ligands and that even subtle changes of the linker structure can have a significant impact on the binding affinity.

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Structural basis of multivalent binding to wheat germ agglutinin.

Multivalency is an important phenomenon in protein–carbohydrate interactions. In order to evaluate glycodendrimers as multivalent inhibitors of carbohydrate binding proteins, we displayed them on a microarray surface. Valencies were varied from 1 to 8, and corrections were made for the valencies so that all surfaces contained the same amount of the sugar ligand. Five different carbohydrates were attached to the dendrimers. A series of fluorescent lectins was evaluated, and for each of them a binding profile was obtained from a single experiment showing both the specificity of the lectin for a certain sugar and whether it prefers multivalent ligands or not. Very distinct binding patterns were seen for the various lectins. The results were rationalized with respect to the interbinding distances of the lectins.

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Rapid screening of lectins for multivalency effects with a glycodendrimer microarray

https://kops.uni-konstanz.de/bitstream/handle/123456789/9830/witt_039.pdf;sequence=1

Caroline Maierhofer

Papers

Structural basis of multivalent binding to wheat germ agglutinin.

Rapid screening of lectins for multivalency effects with a glycodendrimer microarray

Probing multivalent carbohydrate-lectin interactions by an enzyme-linked lectin assay employing covalently immobilized carbohydrates.

2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-1-O-p-nitrophenoxycarbonyl-α-d-glucopyranose