Proteoglycans in human gingiva: Molecular size distribution in epithelium and in connective tissue

The major extracellular, non-fibrous macromolecules in human gingiva are proteoglycans. These sulphated, uronic acid-containing macromolecules are synthesized in vitro by both gingival epithelium and its underlying connective tissue. Biochemical analyses were carried out on cultured human predominantly gingival epithelium and predominantly connective tissue in media containing appropriate radioactive precursor molecules. The proteoglycans were extracted with salt solutions of varying concentration and characterized by means of column chromatography and liquid scintillation counting. The major differences noted between the macromolecules extracted from these two closely apposed regions were molecular size, and the ability or not to form large self-aggregatable macromolecules. In general, the epithelial proteoglycans are larger than connective tissue proteoglycans. Proteoglycans from gingival epithelium are able to self-aggregate to form large macromolecules with mol. wt in excess of 2 × 10⁶ which are essential for the maintenance of tissue integrity.