Carbohydrate-carbohydrate interactions in biological and model systems

Carbohydrate-carbohydrate interactions are emerging as a novel and versatile mechanism for cell adhesion and recognition. Although this interaction has not deserved much attention of cell biologists, biochemists, or carbohydrate chemists, new evidence and studies are confirming the importance of this mechanism for specific cell adhesion and communication. The study and evaluation of carbohydrate-carbohydrate interactions is still in its infancy. Their development will go hand in hand with the development of new and more sensitive techniques to study weak interactions such as biosensors, atomic force microscopy, or weak affinity chromatography. In this contribution we will review these new emerging carbohydrate-carbohydrate related interactions including those already established and those where the carbohydrate involvement, at this moment, may be considered possible as in the case of DNA-carbohydrate interaction. The two main research lines on carbohydrate-carbohydrate interaction in biological systems and the efforts, using model systems, to demonstrate and evaluate these interactions are reviewed here in some detail. Considerations about the intermolecular forces and the mechanism that may be involved in carbohydrate-carbohydrate interactions are also presented. The chapter ends with the review of the few examples existing in the literature on quantitative studies of carbohydrate-carbohydrate interaction with model systems.