Dermatan sulfate (DS) is a glycosaminoglycan (GAG) that is distinguished from chondroitin sulfate (CS) by the presence of iduronic acid (IdoA), the C-5 epimer of d-glucuronic acid (GlcA). IdoA occurs in variable proportions in DS (Fig. 1A) and, as a result of the different position of the carboxyl moiety (Fig. 1B), it generates a more flexible polysaccharide chain, allowing specific interactions with several proteins and polysaccharides. To form CS/DS, three specific enzymes, dermatan sulfate epimerase 1 (DS-epi1), dermatan sulfate epimerase 2 (DS-epi2) and dermatan 4-O-sulfotransferse 1 (D4ST1), are required 1. These enzymes are differently organized in various tissues and, under different physiological conditions, they generate CS/DS of a very different structure. DS is found relatively late in the evolutionary tree and first appears in molluscs, sea urchins and sea cucumbers. It is then found in ascidians and in the whole vertebrate phyla 2. However, it is absent in Caenorhabditis elegans and Drosophila melanogaster. The present review presents the structure, function and biosynthesis of these structurally different CS/DS polymers and explains how they are modified in response to different physiological and pathological processes.
