Structure of Pig Skin Dermatan Sulfate

Abstract

The presence of sulfated uronic acid residues in dermatan sulfate has been known for some time. I n view of the copolymeric nature of pig skin dermatan sulfate, it was of interest to see whether the extra sulfate groups were attached to iduronic acid or glucuronic acid residues.Hyaluronidase-degraded dermatan sulfate was fractionated on Dowex-1 to yield fractions of varying sulfate content. It was observed that the degree of sulfation was inversely proportional to the glucuronic acid content. Oversulfated dermatan sulfate was subsequently treated with chondroitinase-AC to yield a completely glucuronic acid-free polymeric product still bearing all the extra sulfate groups. More direct evidence for the presence of sulfated iduronic acid moieties was obtained by Smith degradation of oversulfated, chondroitinase-AC treated dermatan sulfate. A fast-moving component isolated by preparative electrophoresis had the molar ratio sulfate : hexosamine 1.8 : 1 and contained exclusively L-iduronic acid.The sulfate groups of acidic glycosaminoglycans are generally attached to the hexosamine moieties. However, sulfated uronic acid residues have also been demonstrated ; besides heparin, a number of galactosaminoglycans from various sources have been found to contain uronosyl-sulfate units (for references see [l]). So-called oversulfated dermatan sulfates have thus been isolated from skin of elasmobranches [Z] and urines of Hurler patients [3]. Furthermore, even dermatan sulfate preparations with equimolar proportions of sulfate and hexosamine contain disaccharide units bearing two sulfate residues ; unsaturated dissaccharides with sulfated uronic acid moieties were thus isolated from a chondroitinase digest of dermatan sulfate [l, 41. Although the configurational difference between iduronic and glucuronic acid is eliminated in the unsaturated disaccharides it was suggested that part of the sulfate residues would be located to glucuronic acid moieties [I].During studies on the copolymeric nature of pig skin dermatan sulfate it was observed that polysaccharide fragments reisolated after hyaluronidase degradation were significantly oversulfated [ 5 ] . Since the oligosaccharide fragments containing the bulk of the glucuronic acid residues of the polymer did not show an oversulfation [5] it seems reasonable to suggest that the extra sulfate groups are located to iduronic acid residues.Enzyme. Chondroitinase or chondroitin sulfate glycanohydrolase (EC 3.2.1.34).

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

“…End-group analyses of the two preparations indicated that the low-molecular-weight preparation (II: 2-25-H-40) was enriched in non-reducing terminal fragments, compared with the high-molecular-weight preparation. In agreement with the observation that nonreducing terminal fragments are generally oversulphated (Malmstrom & Fransson, 1971), the sulphate/hexosamine molar ratio of preparation II: 2-25-H-40 was higher than that ofthe high-molecularweight preparation. Finally, oligosaccharides ranging from disaccharide to hexadecasaccharide were also used in the present study (Fransson & Roden, 1967b).…”

“…The resulting fragments which comprise the Liduronic acid-containing regions range from tetrasaccharide (molecular weight approximately 1000) to polysaccharides almost as long as the original polymer. In a previous study it was shown that long fragments (molecular weight 15000) derived from the non-reducing terminal portion of the chain were significantly oversulphated (Malmstrom & Fransson, 1971). Approximately 40% of the oversulphated material was represented by L-iduronic acid sulphatecontaining oligosaccharides (Fransson et al, 1974b).…”

“…hyaluronidase releases prinmarily tetrasaccharides from glucuronic acid-containing glycosaminoglycans (forreferences see Fransson & Rod6n, 1967a,b), a few residual, reducing terminal GlcUA-GalNAc(-SO4) periods remain in the polymer after enzymic treatment (Fransson & Malmstrom, 1971 Fig. 2.…”

Specificities of Three Distinct Human Chondroitin/Dermatan N-Acetylgalactosamine 4-O-Sulfotransferases Demonstrated Using Partially Desulfated Dermatan Sulfate as an Acceptor

“…In the absence of PAPS, the epimerization reaction in the nonsulfated chondroitin is reversible and reaches a particular equilibrium state, where the D-gluco configuration dominates over the L-ido configuration (61). The degree of interconversion to IdoUA is much lower than actual IdoUA contents observed in native DS (62). A marked 4-O-sulfation modification of dermatan has been observed using human skin fibroblast microsomes as an enzyme source (29).…”

Mucopolysaccharidoses

“…The radioactive product was identified as inorganic sulphate by paper chromatography. Other workers (Suzuki et al, 1968;Lindahl and Axelsson, 1971;Malmstrom and Fransson, 1971) Action of the Hunter corrective factor results in the disappearance of some 'oversulphated' areas (about one-third), and it was concluded that since the sulphate residue unique to such areas is that linked to L-iduronic acid, the sulphatase is for sulphated iduronic acid. This was confirmed using the disaccharide 4-O-a-sulphoiduronosyl-D-sulphoanhydromannose as substrate and measuring iduronic acid released by the combined action of Hunter factor and a-L-iduronidase.…”