As glycosaminoglycan

Proteolytic digestion of proteoglycans liberates the carbohydrate side-chains, which are known as glycosaminoglycans (also known as mucopolysaccharides). All the glycosaminogly-cans contain derivatives of glucosamine or galactosamine. Six major groups are known, one of which is heparin. 

Hyaluronic acid is a component of the extracellular ground substance which surrounds the collagen and elastin fibres and cells of connective tissue [64], It is a member of the group of polysaccharides isolated from vertebrate connective tissues which were formerly called mucopolysaccharides and are now more commonly referred to as glycosaminoglycans [65,66], Glycosaminoglycans commonly occur in vivo as proteoglycans. 

ECM, extracellular matrix is a complex network made up of polysaccharides, such as glycosaminoglycans or cellulose and proteins such as collagen, which are secreted by cells. 

Glycoproteins will be discussed in some detail in Section 12.4. The carbohydrate components of proteoglycans are known as glycosaminoglycans. Proteoglycans are essential parts of the connective tissue In mammals and are also present to some extent in fish and bacteria (peptidoglycans from the cell wall of bacteria are different biopolymers and were discussed in Section 7.9). The term mucopolysaccharide was used in the past to describe polysaccharide materials of animal origin containing 2-amino-2-deoxyhexoses. 

Many compounds such as glycosaminoglycans (GAGs), nucleic acids, acidic peptides, or peptides with acidic PTMs such as phosphorylation or sulfation do not readily form positive ions, especially in mixtures where ion formation is favored by the more basic mixture components. When positive ions can be formed, then the spectra are usually characterized by the abundant loss of the PTM (e.g., sulfate from GAG) or, in the case of oligonucleotides, a proton from the sugar-phosphate backbone. 

Chondroitin sulfates (Figure 9.23) are molecules classified as glycosaminoglycans.Two common chondroitin sulfates are chondroitin-4-sulfate and chondroitin-6-sulfate. Each is a polymer of alternating units of D-glucuronate and N-acetyl-D-galactosamine-sulfate linked in a 1-3 linkage. 

For the enzymic analysis of polysaccharide structure, the hydrolytic enzymes are the most useful, and little attention will be paid in this article to other types of enzyme. No consideration at all will be accorded enzymes acting on non-carbohydrate moieties. For diis reason, heteropolysaccharide-peptide and lipopolysaccharide complexes (such as those from bacterial cell-walls) are not discussed, as satisfactory treatment of these would also require mention of other types of enzyme, such as amidases for coverage of this subject, an authoritative text and several reviews - may be consulted. Other types of carbohydrate-containing macromolecule, such as glycosaminoglycans ( mucopolysaccharides ) and glycoproteins, for which it is relatively easy to restrict consideration to the polysaccharide portion, are discussed, but only with reference to their carbohydrate moieties. 

Infrared absorption studies have shown that most biogenic silica is present as gel or dissolved silica. However, emission spectroscopy studies have indicated that some of the soluble silica found in animals is bound to organic molecules, such as glycosaminoglycans, whose structure has yet to be identified(51). 

Although there is often close contact between the RPE processes and the rod outer segment surfaces, much of the retinol is probably delivered to the RPE via the subretinal space rather than by direct membrane-membrane transfer (but see Rando and Bangerter, 1982). It has been estimated that the subretinal space occupies 0.01-0.02 ml in human eyes and 0.03-0.10 ml in cattle eyes. It is filled with an interphotoreceptor matrix (IPM) (Feeney, 1973 Berman 1982) that contains proteoglycans (Adler and Severin, 1981 Adler and Klucznik, 1982). The ratio of protein to proteoglycans (measured as glycosaminoglycans) is greater than 50 1. Over 90% of the IPM remains with the retina when this tissue is separated from the RPE. 

The proteoglycans contain heteropolysaccharides known as glycosaminoglycans, an unwieldy term that emphasizes their content of hexosamines and uronic acids. Formerly glycosaminoglycans were known as mucopolysaccharides. The best known members of this group are the chondroitin sulphates and hyaluronic acid. Though they are characterized by the structure of their polysaccharide chains, these are almost invariably associated with protein, hence the term proteoglycan. 

At the time of the discovery of hyaluronan, the polysaccharides, which represent the major part of the organic material on our planet, were already quite well known. A number of so-called mucopolysaccharides, currently known as glycosaminoglycans, had already been discovered. Hyaluronic acid is known to belong to this class as well. Mucopolysaccharides were isolated from mucus, to which they give viscous lubricating properties. These properties, in turn, are related to glycosaminoglycan s ability to bind to a significant amount of water. 

Finally, it is known that HA as glycosaminoglycan and chondroitin sulphate (CS) protect the urothelium but a damage to the urothelium may increase bacterial adherence and cause infection risk. For this a meta-analysis was carried out in order to evaluate the effect of intravesical HA and HA and CS (HA-CS) combination therapy in recurrent bacterial cystitis in adult women. A systematic literature search was performed. Primary outcomes were urinary tract infection (UTI) rate per patient-year, and UTI recurrence time (days). Secondary outcomes were 3-day voids and pelvic pain and urgency/frequency (PUF) symptom scale total score [35. ... 

---