ABSTRACT
Oligosaccharides found in nature, bound either to proteins or lipids or in free form, usually occur in very complex mixtures. The variability is not only due to the different constituting monosaccharide building blocks, but also the possibilities of different linkage positions, configurations, branching, and substitutions of the hydroxyl and amine groups with, for example, sulfate or acetyl groups. With few exceptions, the oligosaccha rides bound to glycoproteins can be divided into N-and O-linked oligosac charides, the former linked to asparagine and the latter linked to either serine or threonine. The large glycoproteins found on mucosal surfaces, the so called mucins, carry a variety of mostly O-linked oligosaccharides local ized to domains with a high degree of glycosylation [1,2].
