Carbohydrate Microarrays as Essential Tools of Postgenomic Medicine

Carbohydrates are essential biological molecules carrying important biological information. Carbohydrates are prominently displayed on the surface of cell membranes and expressed by virtually all secretory proteins in bodily fluids. This is achieved by the events of posttranslational protein modification called glycosylation. Importantly, expression of cellular glycans, in the form of either glycoproteins or glycolipids, is differentially regulated. Cell display of precise complex carbohydrates is characteristically associated with the stages or steps of embryonic development, cell differentiation, as well as transformation of normal cells to abnormally differentiated tumor or cancer cells. Sugar moieties are also abundantly expressed on the outer surfaces of the majority of viral, bacterial, protozoan, and fungal pathogens. Many sugar structures are pathogen specific, which makes them important molecular targets for pathogen recognition, diagnosis of infectious diseases, and vaccine development. Exploring the biological information content in carbohydrates is one of the current focuses of postgenomic research and technology development. Biophysical, biochemical, and immunological methods have proven very valuable in studying carbohydrate–carbohydrate and carbohydrate–protein interactions. Many well established immunochemical methods have been applied to determine the specificity and cross-reactivity of carbohydrate–antibody and carbohydrate–lectin interactions. A pressing need is, thus, the establishment of high-throughput technologies to enable the large-scale, multiplex analysis of carbohydrates and their cellular receptors. These include especially the characterization of immunological properties of carbohydrates that are important for medical applications of carbohydrate antigens and interactions of carbohydrates with other biomolecules or intact cells that play key roles in establishing comprehensive biological functions of essentially all existing living organisms.