Carbohydrate-carbohydrate interactions: A review

This review deals with a new area of research on biorecognition: carbohydrate-carbohydrate interaction. Seven experimental approaches are described that have been used to detect and investigate this phenomenon, with special reference being given to its mechanisms and peculiarities, particularly in comparison with other types of molecular interactions, Some historical aspects are also considered. The whole body of experimental evidence published on carbohydrate-carbohydrate interactions by the end of 1995 is reviewed. A special chapter is devoted to intercellular adhesion mediated or initiated by carbohydrate-carbohydrate recognition. The main features of carbohydrate-carbohydrate interactions are as follows. Monovalent interaction is of such low affinity that it cannot be detected by routine physical methods such as NMR. However, if polyvalent ensembles of oligosaccharides (e.g., two membranes with a high density of built-in glycolipids) come in contact, specific Ca2+-dependent interaction can be observed which is inhibited by either EDTA antibodies against carbohydrates of by oligosaccharides. Carbohydrate-carbohydrate-mediated cell adhesion is a rapid primary reaction which immediately precedes carbohydrate-lectin (selective) and protein-protein (integrin) adhesion. Le(x)-Le(x)-mediated compaction of membranes and GM(3)-Gg(3)-mediated adhesion of tumor cells provide illustrative examples of such intercellular contacts.