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 frondosa by a new method involving exposure to a divalent cation chelatlor followed by extraction in water. The fibrils have sulfated glycosaminoglycan moieties associated with their surfaces in the middle of the gap zones. The covalently associated constituents of the fibrils include collagen and three glycosaminoglycan-containing molecules, Two of the glycosaminoglycan-containing molecules are proteoglycans that are solubilized by disulfide bond reduction, The third, which is the most abundant of the three, is not solubilized by disulfide reduction, but is solubilized by proteolysis with bacterial collagenase. Molecular collagen was extracted from isolated fibrils by pepsin digestion followed by 1 M NaCl extraction at pH 8, The pepsin-digested collagen was insoluble in acid until it had been separated from the fibril-associated glycosaminoglycans,, The purified collagen is an alpha 1 trimer, Polyclonal antibodies to C. frondosa collagen do not cross-react with Eucidaris tribuloides or rat tail tendon collagen.