Glycosaminoglycans belong to negatively charged heteropolysaccharides combined with a small amount of proteins. GAGs usually absorb large quantities of water and produce a gel-like matrix that forms the basis of a body’s ground substances. The viscous and lubricating properties of mucous secretion are caused by the GAGs. Hence, they are also known as mucopolysaccharides. GAGs also help to maintain the water and salt balance of the body. They also contribute to the slippery nature of mucous secretion, synovial fluid, and vitreous humour of eyes. The negative charge makes the GAG chains to spread in solution and repel each other. They are surrounded by water; when brought together, the molecules slip over each other. GAGs can also be compressed and hence the water can be squeezed out; this helps to occupy less volume. They can also be hydrated and hence occupy a larger volume. This is attributed to the resilience of the synovial fluid and vitreous humour of the eyes. GAGs are cleaved by lysosomes. A huge number of hydrolytic enzymes are needed for this purpose.