Linkage regions between dermatan polysulfates and peptides.

Three different types of dermatan polysulfate peptides I, II and III, isolated from hagfish notochord, hagfish skin and shark skin, all contained serine, xylose and galactose in a molar ratio of about 1.2 : 1 : 2. After beta-elimination-reduction, dermatan polysulfate peptides II and III produced alanine and xylitol in amounts equivalent to the amount of the serine decrease. Accordingly, it was shown that these dermatan polysulfates were linked to peptides by O-glycosidic bond between xylose and serine, as in chondroitin sulfates and dermatan sulfate. However, dermatan polysulfate peptide I produced N-acetylgalactosaminitol, in addition to alanine and xylitol, in a molar ratio of about 2 : 3 : 1, although the increase of alanine was equivalent to the serine decrease. Consequently, it was concluded that the linkage region of dermatan polysulfate peptide I has two types of O-glycosidic bond: one between xylose and serine and the other between N-acetylgalactosamine and serine. This is the first finding of an N-acetylgalactosamine involved in the linkage region of glycosaminoglycans consisting of uronic acid as repeating constituents.