tetrasaccharide

A tetrasaccharide is a type of oligosaccharide composed of four monosaccharide units linked by glycosidic bonds. Like other short-chain carbohydrates, tetrasaccharides can be linear or branched and may be reducing or non-reducing depending on whether a free anomeric carbon remains.

In nature, tetrasaccharides occur in plants and seeds. The best-known examples are stachyose and verbascose, members of the raffinose family oligosaccharides (RFOs). These molecules are typically built from one or more galactose units appended to a sucrose core. Raffinose itself is a trisaccharide, while stachyose and verbascose contain four monosaccharide units. RFOs are common in legumes, whole grains, and some vegetables and are investigated for their roles in plant stress tolerance as well as their nutritional properties.

Dietary considerations are related to human digestion. Most humans lack the enzymes to fully break down many tetrasaccharides from the RFO group, so they pass into the colon largely intact and are fermented by the gut microbiota. This fermentation can produce gas and osmotic effects, which can cause discomfort in some individuals. On the other hand, RFOs and related oligosaccharides are studied for potential prebiotic effects and benefits to certain microbial populations.

Analytical aspects of tetrasaccharides include their identification and structural elucidation via chromatography, mass spectrometry, and specialized enzymatic assays. Their study contributes to understanding carbohydrate diversity, nutrition, and plant physiology.

See also: oligosaccharide, disaccharide, polysaccharide.