Chemical features of aggregatable heparan sulphates from human-lung fibroblasts

The ability of fibroblast heparan sulphate to aggregate was examined by affinity chromatography on agarose gels substituted with heparan sulphate variants from beef-lung tissue (designated HS2-A, HS3-A, and HS4-A) having different tendencies for association. Fibroblast heparan sulphate bound only to HS4-A agarose. The cell-derived material was subdivided into low-, medium-, and high-affinity species by affinity chromatography on HS4-A-agarose. High-affinity variants contained a larger proportion of chains of high molecular weight. Degradation of heparan sulphate by selective periodate-oxidation of glucuronate in regions rich in 2-acetamido-2-deoxyglucose followed by scission in alkali produced fragments comprising the highly irregular, iduronate-rich and N-sulphate-rich domains. The latter were slightly larger in the high-affinity form. By re-oxidation of the irregular domains, the location of glucuronate residues was identified. The degradation pattern, i.e., the distribution of iduronate-containing repeats, was markedly similar in the high-affinity variant and in the HS4-A chains that were used as affinity ligands. It is suggested that the strength and specificity of heparan sulphate self-association is dependent on complementary and co-operative associations between a number of contact zones.