COVALENT COMPOSITION OF COLLAGEN FIBRILS FROM THE DERMIS OF THE SEA-CUCUMBER, CUCUMARIA-FRONDOSA, A TISSUE WITH MUTABLE MECHANICAL-PROPERTIES

Intact collagen fibrils were isolated from the dermis of Cucumaria fro ndosa by a new method involving exposure to a divalent cation chelatlo r followed by extraction in water. The fibrils have sulfated glycosami noglycan moieties associated with their surfaces in the middle of the gap zones. The covalently associated constituents of the fibrils inclu de collagen and three glycosaminoglycan-containing molecules, Two of t he glycosaminoglycan-containing molecules are proteoglycans that are s olubilized by disulfide bond reduction, The third, which is the most a bundant of the three, is not solubilized by disulfide reduction, but i s solubilized by proteolysis with bacterial collagenase. Molecular col lagen was extracted from isolated fibrils by pepsin digestion followed by 1 M NaCl extraction at pH 8, The pepsin-digested collagen was inso luble in acid until it had been separated from the fibril-associated g lycosaminoglycans,, The purified collagen is an alpha 1 trimer, Polycl onal antibodies to C. frondosa collagen do not cross-react with Eucida ris tribuloides or rat tail tendon collagen.