The co-polymeric structure of pig skin dermatan sulphate. Distribution of L-iduronic acid sulphate residues in co-polymeric chains

Abstract

1. Pig skin dermatan sulphate was degraded by periodate oxidation followed by alkaline elimination or by chondroitinase-ABC to quantify irregular repeating units, i.e. those containing D-GlcUA (D-glucuronic acid) and L-IdUA-SO4 (sulphated iduronic acid). 2. Previous results of periodate oxidation (Fransson, 1974) indicated repeating sequences in pig skin dermatan sulphate containing, on average, 3D-GlcUA, 9 L-IdUA-SO4 or 28 L-IdUA units in addition to N-acetylgalactosamine sulphate. However, complete digestion with chondroitinase-ABC yielded, at the most, 3-4 disulphated disaccharides/ chain. Consequently, more than one-half of the L-IdUA-SO4 residues were present in monosulphated periods, i.e. IdUA-(SO4)-GalNAc. 3. To determine the location of L-IdUA-S04 residues along the copolymeric chain dermatan sulphate was digested with testicular hyaluronidase. (This enzyme cleaves GalNAc-GlcUA bonds within block regions containing D-GlcUA.) By NaB3H4 reduction GalNAc residues located in the reducing end of the fragments were converted into [3H]GalNAcOH (N-acetylgalactosaminitol). Finally, the radioactive product was fragmented by periodate oxidation followed by alkaline elimination. The bulk of the radioactivity was associated with periodate-resistant oligosaccharides indicating that clusters of GlcUA-GalNAc-SO4 periods are often adjacent to a varying number (n = 1-4) of L-IdUA-SO4-containing periods. 4. To study the distribution of L-IdUA-SO4-containing periods in relation to blocks of IdUA-GaINAc-SO4 periods different fractions of hyaluronidase-degraded dermatan sulphate were degraded separately. In all types of fragments (mol.wts. 1500-10000) L-IdUA-SO4-containing periods were demonstrated. In short fragments reducing terminal was found confirming that these sequences were joined to relatively long D-GlcUA-containing block sequences via GalNAc-6-SO4. Moreover, low-molecular-weight oligosaccharides composed of alternating sequences were encountered. An octasaccharide derived from the carbohydrate sequence -GalNAc ---GlcUA-GaINAc-IdUA-GaINAc-GlcUA-GalNAcIdUA-GalNAc---GlcUA-GalNAc (---indicates the position of cleavage by hyaluronidase) was identified.

Glycoform Quantification of Chondroitin/Dermatan Sulfate Using a Liquid Chromatography−Tandem Mass Spectrometry Platform

“…DS has previously been indicated to contain high levels of IdoA-GalNAc4S repeats, with lower levels of IdoA2S-GalNAc4S and GlcA (β1-3) GalNAc6S (β1-4) repeats (35,36,(44)(45)(46). Previous tandem mass spectrometric analysis on the DS preparations investigated in this work showed that the abundances of CSB-like repeats was found to be 90.0%, 75.0%, and 50.0% for DS18, DS36, and DS50 respectively (47).…”

Molecular Cloning and Characterization of a Dermatan-specific N-Acetylgalactosamine 4-O-Sulfotransferase

“…7). While such sequences have been described in dermatan (37,38), they represent minor components in the mature proteoglycan. The selective sulfation of IdoUA-GalNAc that is flanked by GlcUA-GalNAc suggests that sulfation of GalNAc in dermatan is immediately followed by the epimerization of GlcUA to IdoUA.…”

Hybrid glycosaminoglycans synthesized by monolayers of chick embryo arterial fibroblasts

“…Sulfated glucuronic acid has not been reported in these polymers previously, but sulfated iduronic acid residues have been identified in pig skin dermatan sulfate (Fransson et al, 1974a,b;Coster et al, 1975) and shark cartilage . In pig skin the iduronic acid sulfate is linked to an unsulfated GalNAc residue (Ciister et al, 1975), a sequence not found in the present work.…”

“…(iduronic acid-Nacetylgalactosamine 6-or 4-sulfate),; (5) higher oligosaccharides containing iduronic acid and N-acetylgalactosamine 4-sulfate. Coster et al, 1975;Malmstrom et al, 1975a). All of these polymers occur as protein-polysaccharides in which the repeating disaccharide units are linked to a core protein through a unique galactosyl-galactosyl-xylose linkage region (Roden & Horowitz, 1978).…”