Connective tissue glycosaminoglycan

Polysaccharide lyase Family 8 (PL 8). This family encompasses lyases acting upon mammalian connective tissue glycosaminoglycans, and for this reason is the best investigated, with a number of crystal structures available. It has a two-domain fold with an (a/ot)5 toroid connected to a domain almost exclusively of (3-sheet. The reactions catalysed are syn eliminations, with available evidence indicating an irreversible 1cb mechanism, in which the intermediate enolate is stabilised by hydrogen bonding, rather than metal ions, and both deprotonation of C5 and protonation of 04 are carried out by the same tyrosine residue. 

With the exception of keratan sulphate, which contains galactose residues in place of uronic acid, the composition of connective tissue glycosaminoglycans shows variations on the theme described in the previous paragraph (Table 27.2). Hyaluronic acid is only weakly addic, whereas the chondroitin sulphates have strongly addic sulphate groups. 

The connective tissue glycosaminoglycans are readily broken down within the body and numerous data on the turnover rates of hyaluronic add and the chondroitin sulphates have shown their half-lives to vary from 2 to 4 days depending on the type of glycosaminoglycan, the organ and the age of the animal. 

Proteoglycans Glycosaminoglycans (mucopolysaccharides) bound to protein chains in covalent complexes. Proteoglycans are present in the extracellular matrix of connective tissue. 

Dermatan sulfate, also termed chondroitin sulfate B, a related glycosaminoglycan constituent of connective tissue, was known to be composed of galactosamine and a uronic acid, originally believed to be glucuronic acid but then claimed to be iduronic acid based largely on color reactions and paper chromatography. However, the d or L-enantiomer status of the latter monosaccharide was not clear. Jeanloz and Stoffyn unequivocally characterized the monosaccharide as L-iduronic acid by consecutive desulfation, reduction, and hydrolysis of the polysaccharide, followed by isolation of the crystalline 2,3,4-tri-0-acetyl-l,6-anhydro-/ -L-idopyranose, which was shown to be identical to an authentic specimen synthesized from 1,2-0-isopropylidene-/ -L-idofuranose.34... 

Kariya, Y., Watabe, S., Ochial, Y., Murata, K., and Hashimoto, K. (1990). Glycosaminoglycan involved in the cation-induced change of body wall structure of sea cucumber Stichopus japonicus. Connect. Tissue Res. 25,149-159. 

The ICD of the dyes bound to saccharides through an ionic coupling or hydrophobic interaction may remain a conflicting problem. The side-chain chromophores covalently bound to saccharides permit CD bands in the far or near ultraviolet region. These side-chain chromophores can exhibit CD and thus provide more definitive information on the conformation of saccharide moieties. Thus, acetamide CD has been observed to reflect polymer secondary structure of glycosaminoglycans, which are the connective-tissue proteoglycans. 

M. R. Shetlar, C. L. Shetlar, C. W. Kischer, and J. Pindur, Implants of keloid and hypertrophic scars into the athymic nude mouse Changes in the glycosaminoglycans of the implants. Connect. Tissue Res., 26... 

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. 

The vitreous humor is a viscoelastic connective tissue composed of small amounts of glycosaminoglycans, including hyaluronic acid, and of such proteins as collagen.The collagen fibrils are anchored directly to the basal lamina, which forms the boimdaries of the lens, the ciliary body epithelium, and the neuroglial cells of the retina. Although the anterior vitreous is cell free, the posterior vitreous contains a few phagocytic cells, called hyalo-cytes, and is sometimes termed the cortical tissue layer. 

Keywords connective tissue, regeneration, protein synthesis, RNA, silocanes, silatranes, glycosaminoglycanes... 

The acetylated compound is a widespread unit of animal glycosaminoglycans in connective tissue (Chondroitin sulfate, dermatan sulfate) and component of many bacterial immunopolysaccharides and glycoproteins... 

---