Synthetic Lectins for Oligosaccharide Binding in Aqueous Media

Synthetic receptors can help to throw light on the processes of life by mimicking the interactions between biomolecules. The binding of carbohydrates is especially mysterious, and especially difficult to reproduce under natural (aqueous) conditions. We have recently demonstrated the first well-authenticated receptor for the common monosaccharides in water. Our design may be likened to a classical temple, in which roof, floor and pillars make contact with matching portions of the carbohydrate. We have also studied a longer analogue ( extended-temple ) designed to bind disaccharides in (less challenging) organic media. This latter compound shows extraordinary selectivity for just one disaccharide substrate.We now plan to make receptors which will bind di- and oligosaccharides in water - the first molecules to be specifically designed for this purpose. The receptors are likely to show high affinities, perhaps comparable with some carbohydrate-binding proteins (lectins). They should also show good selectivities for particular disaccharide units which are found in plant, fungal and bacterial cell walls. We will use them to study the driving forces for natural carbohydrate binding, for example by varying their structures and the medium in which they operate. We will also develop versions which can be applied in biological research. One aim is to highlight the target disaccharides in developing cell walls, using fluorescent analogues of the receptors. Another is to interrupt cell wall synthesis, perhaps leading to antimicrobial agents. If we succeed we will have demonstrated, for the first time, that biomimetic carbohydrate receptors can be useful in a biological context.