Protein--carbohydrate interactions: learning lessons from nature.

Protein--carbohydrate interactions are at the heart of many important biological processes including signalling, recognition and catalysis. A deeper understanding of these interactions at the molecular level will enable the development of novel, effective and highly selective therapeutics. Glycosyltransferases and glycosidases, carbohydrate-processing enzymes responsible for the synthesis and breakdown of oligosaccharides, have emerged as important targets in the fight against bacterial and fungal pathogenesis, cancer and AIDS. Binding and recognition phenomena are essential processes by which the body exerts control over complex biological functions. In this regard, heparin has retained ongoing interest reflecting its importance as a major pharmaceutical. Recent studies on heparin have shed light onto the mechanisms of cross-reactivity that cause life-threatening side effects and have provided impetus for the development of more selective anti-clotting agents. Important targets for therapeutic intervention are the binding processes mediated through multivalent protein--carbohydrate interactions, such as the interactions of bacterial toxins with cell-surface receptors.