What is "oligosaccharide"

n. (context carbohydrate English) a polysaccharide of low molecular weight, being a polymer of between three and seven monosaccharide units

n. any of the carbohydrates that yield only a few monosaccharide molecules on complete hydrolysis

An oligosaccharide (from the Greek ὀλίγος olígos, "a few", and σάκχαρ sácchar, "sugar") is a saccharide polymer containing a small number (typically three to ten) of simple sugars (monosaccharides). Oligosaccharides can have many functions including cell recognition and cell binding. For example, glycolipids have an important role in the immune response.

In general, they are found either N- or O-linked to compatible amino acid side-chains in proteins or to lipid moieties (see glycans). N-linked oligosaccharides are found attached to asparagine via a beta linkage to the amine nitrogen of the side chain. Alternately, O-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain.