Sugar acids dermatan sulfate

The methylated derivatives served as the basis of elegant studies in which Jeanloz and his colleagues unequivocally established the structure of hyaluronan, dermatan sulfate, and the chondroitin sulfates. They also clarified many confusing issues, including the position of the sulfate groups in these polymers. In the course of this work, they proved that dermatan sulfate contained L-iduronic acid, a sugar not known before to occur in nature. 

Dermatan sulfate is derived from chondroitin 4-sulfate by the action of a C-5 epimerase that inverts the carboxyl group of the /3-D-glucuronic acid, giving the very rare sugar, a-L-idopy-... 

Fig. 1. Alternating sugars of hyaluronic acid, chondroitin/dermatan sulfate and keratan sulfate glycosamino-...

The presence of both glucuronic add and a-linkages in heparin and heparitan sulfate results in a polysaccharide resistant to hydrolysis, and the uronic acid part is decarboxylated before the amino sugar part is completely released. Similar difficulties are encountered in the hydrolysis of chondroitin 4- and 6-sulfates (chondroitin sulfates A and C), whereas dermatan sulfate ()8-heparin, chondroitin sulfate B) can be hydrolyzed under conditions mild enough to allow the isolation of iduronic add. 

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