Characterization of acid-soluble collagens from the cartilages of scalloped hammerhead (Sphyrna lewini), red stingray (Dasyatis akajei), and skate (Raja porosa)

Acid-soluble collagen from the cartilages of scalloped hammerhead (Sphyrna lewini, ASC-S), red stingray (Dasyatis akajei, ASC-D), and skate (Raja porosa, ASC-R) were isolated with yields of 5.64 +/- 0.41, 8.72 +/- 0.31, and 6.74 +/- 0.28% on the basis of wet weight, respectively. ASC-S, ASC-D, and ASC-R had glycine as the major amino acid with contents of 220, 231, and 228 residues/1,000 residues, respectively, and contained imino acid of 174, 155, and 142 residues/1,000 residues, respectively. Three kinds of collagens more likely were comprised of 2 types of collagen (type I and II) and had some differences in primary structures. The denaturation temperatures (T(d)s) of the ASC-S, ASC-D, and ASC-R were 23.8, 15.1, and 12.1A degrees C, respectively. Maximum solubility of the 3 ASCs in 0.5 M acetic acid was observed at pH 2, and a sharp decrease in solubility above 2%(w/v) was observed in the presence of NaCl. The 3 lyophilized collagens displayed loose, fibrous, and porous structures.