Glycan

The terms glycan and polysaccharide are defined by IUPAC as synonyms meaning 'compounds consisting of a large number of monosaccharides linked glycosidically'. However, in practice the term glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein, glycolipid, or a proteoglycan, even if the carbohydrate is only an oligosaccharide. Glycans usually consist solely of O-glycosidic linkages of monosaccharides. For example, cellulose is a glycan (or, to be more specific, a glucan) composed of β-1,4-linked D-glucose, and chitin is a glycan composed of β-1,4-linked N-acetyl-D-glucosamine. Glycans can be homo- or heteropolymers of monosaccharide residues, and can be linear or branched.Glycans can be found attached to proteins as in glycoproteins and proteoglycans. In general, they are found on the exterior surface of cells. O- and N-linked glycans are very common in eukaryotes but may also be found, although less commonly, in prokaryotes.A 2012 report from the U.S. National Research Council calls for a new focus on glycoscience, a field that explores the structures and functions of glycans and promises great advances in areas as diverse as medicine, energy generation, and materials science. Until now, glycans have received little attention from the research community due to a lack of tools to probe their often complex structures and properties. The report presents a roadmap for transforming glycoscience from a field dominated by specialists to a widely studied and integrated discipline.See glycolipidsSee glycophosphatidylinositolThe following are examples of the commonly used techniques in glycan analysis: