They contain two or more different monosaccharide units. They are also called heteroglycans.
Polysaccharides are of two main types. 1. Homopolysaccharides 2. Heteropolysaccharides Heteropolysaccharides are further classified as: a) GlycosAminoGlycans (GAGs) b) Glycoconjugates c) Mucilages Proteoglycan is a type of glycoconjugates whereas heparan sulfate, dermatan sulfate and hyaluronic acid are examples of GAGs.
The carbohydrate that has a sugar acid and sugar amine disaccharide repeat unit are called heteropolysaccharides.
Actually, proteoglycans are conjugates of proteins and carbohydrates in which there is more carb and less protein. In fact, proteoglycans have GAGs (heteropolysaccharides) as carbohydrates. Glycoproteins, on the other hand, have more protein and less carb. Here, carbohydrates are in the form of Oligosaccharides.
heteropolysaccharides are composed of more than one monosaccharides and can contain chemical decorations (e.g. pyryvl, acetyl and succinyl). Succinoglycan is a simple example of heteropolysaccharide.