PROPOSED RESOLUTION OF THE PARADOX OF EXTENSIVE CROSSLINKING AND LOW TENSILE-STRENGTH OF CUVIERIAN TUBULE COLLAGEN FROM THE SEA-CUCUMBER HOLOTHURIA-FORSKALI

The extruded tubules of the sea cucumber possess the amino acid composition, intermolecular crosslinking and fiber banding patterns typical of mammalian collagen fibers. Despite this resemblance, particularly the crosslinking normally associated with high tensile strength, the tubule fibers are extremely extensible. The molecules probably are crosslinked through the normal head-to-tail mechanism. Further transverse crosslinking between the irregular fibrils probably is inhibited by the surrounding sheath of glycosaminoglycan, which also serves as a lubricant, thus, allowing slippage of adjacent fibrils under tension.