Vitreous humor polysaccharide

Chitin is a heteropolysaccharides, which is made up of glycans such as Hyaluronic acid, an alternating polysaccharide of D-glucuronic acid and N-acetyl-D-glucosamine MW to 5,000,000 which serves as a lubricant in joints and is a component of the vitreous humor. 

Hyaluronic acid consists of repeating disaccharides of /3-D-glucopyranosyluronic acid-(l— 3)-iV-acetyl-D-galactosamine linked p- l 4) to the next disaccharide. This proteoglycan can have between 500 and 50,000 residues per chain [92]. Hyuronic acid is found widely distributed in mammalian cells and tissues, where it is found in synovial fluid that lubricates the joints, in the vitreous humor of the eye, and in connective tissue, such as the umbilical cord, the dermis, and the arterial wall. It also occurs as a capsular polysaccharide around certain bacteria, such as pathogenic streptococci [92]. 

Later, a more detailed investigation was performed by Karl Meyer, who summarized the results as follows [9] "From the vitreous humor of cattle eyes a polysaccharide acid of high molecular mass has been obtained... As constituents there have been recognized a uronic acid, an amino sugar... It appears to be a substance unique in higher animals, and may be best compared with some of the specific polysaccharides of bacteria... We propose, for convenience, the name "hyaluronic acid", from hyaloid (vitreous) + uronic acid". 

Meyer K, Palmer JW. The polysaccharide of the vitreous humor. J Biol Chem 1934 107 629-634. 

Meyer K, Palmer JW, Smyth EM. Glycoproteins. II. The polysaccharides of vitreous humor and of umbilical cord. J Biol Chem 1936 114 689-703. Weissman B, Meyer K. The structure of hyalobiuronic acid and of hyaluronic acid from umbilical cord. J Am Chem Soc 1954 76 1753-1757. 

Mengher LS, Pandher KS, Bron AJ, Davey CC. Effect of sodium hyaluronate (0.1%) on break-up time (NIBUT) in patients with dry eyes. Br J Ophthalmol 1986 70 442-447 Meyer DR, McCulley JP. Different prospects of risk management from in vitro toxicology and its relevance to the evolution of viscoelastic formulations. Rosen ES (ed) Viscoealstic Materials Basic Science and Clinical Applications. New York, Pergamon Press, 1989, S. 45-90 Meyer K, Palmer JW. The polysaccharide of the vitreous humor. J Biol Chem 1934 107 629-634 Meyer K. Chemical structure of hyaluronic acid. Fed Proc 1958 17 1075-1077... 

Hyaluronic acid was first isolated by Karl Meyer from vitreous humor (30) and later from umbilical cord, synovial fluid, skin, cock s comb, certain fowl tumors, groups A and C hemolytic streptococci, and other sources 31). Historically, it has been a major and frequent if not universal component of Levene s so-called mucoitin sulfates. The polysaccharide acts in animal tissue presumably as an integral part of the gel-like ground substance of connective tissue (and other tissues). Another important function of hyaluronic acid in animals is serving as a lubricant and shock ab-sorbant in the joints. 

---