What is "glycosaminoglycan"

n. (context carbohydrate English) any polysaccharide that is a polymer of amino sugars; they are the carbohydrate units of proteoglycans

Glycosaminoglycans (GAGs) or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit (except for keratan) consists of an amino sugar ( N-acetylglucosamine or N-acetylgalactosamine) along with a uronic sugar ( glucuronic acid or iduronic acid) or galactose. Glycosaminoglycans are highly polar and attract water. They are therefore useful to the body as a lubricant or as a shock absorber.

Mucopolysaccharidoses are a group of metabolic disorders in which abnormal accumulations of glycosaminoglycans occur because of enzyme deficiencies.