Structure–Function Relationship of Glycosaminoglycans

Because of the high concentration of negative charges, these heteropolysaccharide chains tend to be extended in solution. They repel each other and are surrounded by a shell of water molecules. When brought together, they slide past each other, much as two magnets with the same polarity seem to slide past each other. This produces the slippery consistency of mucous secretions and synovial fluid.

When a solution of GAG is compressed, the water is squeezed out, and the GAG are forced to occupy a smaller volume. When the compression is released, the GAG spring back to their original, hydrated volume because of the repulsion of their negative charges. This property contributes to the resilience of synovial fluid and the vitreous humor of the eye (Fig. 1).

Figure 14.3 Resilience of glycosaminoglycans.