Chondroitin sulfates 4- and

The major GAGs are hyaluronic acid, chondroitin 4- and 6-sulfates, keratan sulfates I and II, heparin, heparan sulfate, and dermatan sulfate. 

Differences between the 13C-n.m.r. spectra of chondroitins have been used to show that specimens of chondroitin 4- and 6-sulfate contain up to 30% of impurities, and appear to be composites of both... 

Animal polysaccharides containing D-glucuronic acid include heparan sulfate,108 chondroitin 4- and 6-sulfates,109 and hyaluronic acid.109... 

Hyaluronidase from Flavobaaerium and Proteus vulgaris has been shown to hydrolyze chondroitin-4- and -6-sulfate and to possess weak activity toward dermatan sulfec [30]. Hyaluronidase from Streptomyces hyaiurolyacus... 

The 220-MHz spectra of chondroitin 4- and 6-sulfate, and of dermatan sulfate, were consistent with structures that had previously been proposed for these compounds, in contrast to the 220-MHz spectrum of keratan sulfate.136 The spectra of chondroitin 6-sulfate, keratan sulfate, and viscous solutions of hyaluronic acid showed broad bands, and, for hyaluronic acid, little structural information could be deduced from its spectrum.136... 

Histochemical techniques for detecting substrate before and after enzyme treatment are extremely useful in studies on cellular structure. One of the oldest histochemical tests utilized saliva to identify suspected glycogen or starch. More definitive results are obtained when thin sections of a tissue are incubated in a buffered solution of purified amylase and stained for poly-utc-glycols. Material stained by periodic acid-Schiff reagent in the control, but not in the section exposed to amylase, is assumed to be glycogen or starch. Two more of the numerous histochemical techniques associated with localization of substrate are—using hya-luronidase to locate hyaluronic acid and chondroitin 4- and 6-sulfates (179) and using neuraminidases to locate sialomucins (180). By use of electron microscopy in combination with the histochemical technique subcellular localization can be obtained. 

Chondroitin 4- and 6-sulfates were originally designated as chondroitin sulfate A and C, respectively, and the close similarity in structure between them is demonstrated by the fact that both mucopolysaccharides yield the same disaccharide (chondrosine) on controlled, acidic hydrolysis together with sulfuric and acetic acids. Chondroitin 4-sulfate or chondroitin 6-sulfate, or both, occur in cartilage and adult bone, and the former mucopolysaccharide is a minor constituent of ligamentum nuchae and cornea (M17). Chondroitin 6-sulfate is a minor constituent of umbilical cord and occurs with dermatan sulfate (chondroitin sulfate B) and hyaluronic acid in heart valves and adult connective tissue (M17). An acid mucopolysaccharide isolated from human plasma resembles chondroitin 4-sulfate in its properties (S4). 

Dermatan sulfate may be distinguished from chondroitin 4- and 6-sulfates in that it is not degraded by testicular hyaluronidase and, furthermore, the desulfated mucopolysaccharide is unattacked by testicular and bacterial hyaluronidases (M17). Further diflFerentiation of dermatan sulfate from hyaluronic acid and the foregoing chondroitin sulfates is readily made on the basis of color reactions given by the different uronic acid components. Dermatan sulfate shows equimolar ratios of uronic acid ihexosamine sulfate when the uronic acid content is determined by the orcinol (K7) or decarboxylation (T4) methods, whereas significantly lower values are obtained by the carbazole method (D8). 

This mucopolysaccharide, possessing a strueture similar to those of chondroitin 4- and 6-sulfates but with a small content of sulfate, was isolated from bovine cornea (M16). Chondroitin resembles hyaluronic acid in its rate of hydrolysis by testicular and bacterial hyaluronidases, but was differentiated from hyaluronic acid ([a]n —65° to — 78°) by its optical rotation ( [o]d — 21°). Its structural similarity to chondroitin 4- and 6-sulfates was indicated by the fact that chondrosine was released in high yield on controlled, acidic hydrolysis (D3). The isolation of this mucopolysaccharide is of particular interest since it may be a precursor in the biosynthesis of chondroitin 4- and 6-sulfates. 

Commercial preparations usually contain this type of hyaluronidase. The enzyme is found in testicular tissue of most mammals and is located in the acrosomal cap of spermatozoa [6], Testicular hyaluronidase degrades hyaluronan, chondroitin, chondroitin-4- and -6-sulfate to oligosaccharides, mainly tetrasaccharides [1]. Partial degradation of dermatan sulfate has been described [7]. Testicular hyaluronidase had a broad pH range of activity [5]. 

Bollet et al. [11] demonstrated the presence of hyaluronidase activity in various mammalian tissues. They showed that this type of hyaluronidase differed from the testicular type concerning pH optimum and pH range of activity. Subsequent studies revealed that the enzyme was present in the lysosomal fraction of the tissues [12]. The liver is an especially rich source [13]. Degradation of hyaluronan leads to the same end products as testicular hyaluronidase [11]. Lysosomal hyaluronidase from rat liver degrades chondroitin-4- and -6-sulfate, but not dermatan sulfate, desulfated dermatan sulfate, heparan sulfate, keratan sulfate, or heparin [14], Lysosomal hyaluronidase has an acid pH optimum and a narrow pH range of activity [14]. This difference in pH profile of activity has commonly been used to differentiate between testicular and lysosomal hyaluronidase. A similar acid-active hyaluronidase is present in human serum [15]. 

Animal venoms usually possess hyaluronidase activity [17]. The enzymatic properties, including hyaluronidase, of snake venoms have been extensively studied by Tan et al. [18]. Snake hyaluronidase acts on hyaluronan, chondroitin, and chondroitin-4- and -6-sulfate, producing various oligosaccharides, mainly tetrasaccharides [1]. 

These /8-elimination reactions, which were proved for n-glucopyran-uronate derivatives, belong to the class of axialr-equatorial reactions (type B). This type of enolacetal-forming, /8-elimination reaction is found in the enzyme-catalyzed degradation of hyaluronic acid and chondroitin 4- and 6-sulfates. 

Young human placenta contains more glycosaminoglycan than term placenta (L9). Although there are similar quantities of hyaluronic acid and chondroitin 4- and 6-sulfates, the younger placenta contains a greater proportion of chondroitin. The chondroitin sulfates of the early tissue also contain a higher proportion of unsulfated disaccharide units, and the dermatan sulfate of the young tissue is more susceptible to hyaluroni-dase (EC 3.2.1.35) than term tissue. 

Cultured skin fibroblasts from a case in which chondroitin 4- and 6-sulfates are excreted in excess (see p. 89) are severely deficient in S-D-glucuronidase activity (H4), these fibroblasts showing an excessive accumulation and lengthened turnover time of sulfate-containing glycos-aminoglycan. The abnormal glycosaminoglycan metabolism can be cor-... 

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