<unk>  <unk> , also called keratosulfate, is any of several sulfated glycosaminoglycans (structural carbohydrates) that have been found especially in the cornea, cartilage, and bone.<unk> s are large, highly hydrated molecules which in joints can act as a cushion to absorb mechanical shock.
Keratan sulfate
Dermatan sulfate
Chondroitin sulfate
Heparan sulfate
Phlyctenule
Hyaluronic acid 
Pentosan polysulfate
Crystallin