MUCOPOLYSACCHARIDES OF CONNECTIVE TISSUE 33 1 



The contrast between the anticoagulant properties of chondroitin 

 sulphuric acids-A and -B suggests that the substitution of L-iduronic acid 

 for D-glucuronic acid alters biological properties. It is possible that anti- 

 thrombic activity is related to some molecular characteristics which also 

 confers an increased capacity to bind certain ions [i8]. Hoffman et al. 

 [13] suggested that chondroitin sulphuric acid-B is associated with coarser 

 collagen bundles. This polysaccharide has been found in a variety of sites. 

 It was identified in gastric mucosa by Smith and Gallop [19] and has been 

 found in rabbit skin by Schiller et al. [20]. Of particular interest is the fact 

 that chondroitin sulphuric acid-B and heparin monosulphuric acid are 

 excreted in the urine and found in the tissues of patients afflicted with the 

 Hurler syndrome [21]. The enzymic defect in this heritable disorder of 

 connective tissue is unknown. 



Davidson and Meyer [22] isolated from cornea a fraction composed of 

 D-glucuronic acid and N-acetylgalactosamine and less than one mole of 

 sulphate per disaccharide repeating unit. It was suggested that this com- 

 pound, chondroitin, is a metabolic intermediate in the biosynthesis of 

 chondroitin sulphuric acids-A and -C. Suzuki and Strominger [23] have 

 recently demonstrated the transfer of radioactive sulphate from PAPS * to 

 a chemically desulphated chondroitin sulphate by an enzyme isolated from 

 chicken oviducts, suggesting that sulphation of chondroitin sulphate 

 occurs at the macromolecular stage. This pathway cannot be considered as 

 established since the amount of sulphate incorporated was extremely low, 

 and biosynthesis of chondroitin has not yet been achieved. The physio- 

 logical and metabolic role of chondroitin must yet be considered uncertain. 



Unlike other mucopolvsaccharides, keratosulphate lacks a uronic acid 

 component. Instead, a galactose group is substituted. Hirano et al. [24] 

 have indicated that the galactosyl bond is 1^4 and the glucosaminidic 

 bond is 1^3 with sulphate substituted on carbon 6 of the amino sugar. 

 Keratosulphate has been isolated from the nucleus pulposus [25]. Shetlar 

 and Masters [26] and Kuhn and Leppelmann [27] demonstrated an 

 increase in the ratio of glucosamine to galaciosamine in cartilage with 

 advancing age. This observation has found explanation in the demon- 

 stration by Kaplan and Meyer [28], that rib cartilage of the human adult 

 contains a large proportion of keratosulphate in contrast to the absence of 

 this substance in rib cartilage of newborns. Even larger amounts of kerato- 

 sulphate were reported in patients with the Marfan syndrome, although 

 it is dubious whether the difference was significant. Hallen [29] similarly 

 found that the relative concentration of glucosamine in nucleus pulposus 

 increased with advancing age. This was interpreted as an increase of 

 keratosulphate /chondroitin sulphate ratio. Davidson and Woodhall [30] 



* '3-phosphoadenosine 5'-phosphosulphate. 



