Molecular organization of heparan sulphate from human skin fibroblasts.
The molecular structure of human skin fibroblast heparan sulphate was examined by specific chemical or enzymic depolymerization and high-resolution separation of the resulting oligosaccharides and disaccharides. Important features of the molecular organization, disaccharide composition and O-sulphate disposition of this heparan sulphate were identified. Analysis of the products of HNO2 hydrolysis revealed a polymer in which 53% of disaccharide units were N-acetylated and 47% N-sulphated, with an N-/O-sulphate ratio of 1.8:1. These two types of disaccharide unit were mainly located in separate domains. Heparitinase and heparinase scission indicated that the iduronate residues (37% of total hexuronate) were largely present in contiguous disaccharide sequences of variable size that also contained the majority of the N-sulphate groups. Most of the iduronate residues (approx. 70%) were non-sulphated. About 8-10% of disaccharide units were cleaved by heparinase, but only a minority of these originated from contiguous sequences in the intact polymer. Trisulphated disaccharide units [alpha-N-sulpho-6-sulphoglucosaminyl-(1----4)-iduronate 2-sulphate], which are the major structural units in heparin, made up only 3% of the disaccharide units in heparan sulphate. O-Sulphate groups (approx. 26 per 100 disaccharide units) were distributed almost evenly among C-6 of N-acetylglucosamine, C-2 of iduronate and C-6 of N-sulphated glucosamine residues. The results indicate that the sulphated regions of heparan sulphate have distinctive and potentially variable structural characteristics. The high content of non-sulphated iduronate in this heparan sulphate species suggests a conformational versatility that could have important implications for the biological properties of the polymer.
Turnbull
J E
JE
Department of Clinical Research, University of Manchester, Christie Hospital and Holt Radium Institute, U.K.
Gallagher
J T
JT
D002240:Carbohydrate Sequence; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D006497:Heparan Sulfate; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000032:analysis; D012867:Skin / Q000378:metabolism*
D006025:Glycosaminoglycans; D006497:Heparan Sulfate; D009844:Oligosaccharides