Comparative analysis of the structure and thermal stability of sea urchin peristome and rat tail tendon collagen.

We have purified collagen from two distinct sources; the vertebrate, rat tail tendon and an invertebrate, sea urchin adult tissue, the peristome. The collagenous nature of the purification products was confirmed by amino acid compositional analysis. Both preparations had high contents of glycine and proline residues and hydroxyproline was also present. The total pyrrolidine (proline+hydroxyproline) content decreased from 17.9 mole% in rat tail collagen to 12.9 mole% in peristome collagen. Distinctly different circular dichroic spectra were measured for these collagens. Analyses of spectra, measured as a function of temperature, revealed distinct thermal denaturation profiles. The melting temperature for rat tail collagen was 38.5 degrees C, while the corresponding value for peristome collagen was significantly lower at 27 degrees C. A similar thermal denaturation profile was obtained for rat tail collagen in digestion experiments using a 41-kDa gelatinase activity, isolated from sea urchin eggs. These results identify structural differences between a typical, vertebrate type I fibrillar collagen and an echinoderm collagen which serves as a constituent of a mutable connective tissue. These differences may relate to the functional roles played by collagen in these distinctly different tissues. Copyright 2001 Wiley‐Liss, Inc.