Characterization and subunit composition of collagen from the body wall of sea cucumber Stichopus japonicus

Pepsin-solubilized collagen (PSC) without telopeptides was prepared from the body wall of the sea cucumber Stichopus japonicus and isolated by selective precipitation with NaCl. The PSC exhibited a maximum absorbance at 220 nm. The subunit of PSC was isolated by Sephacryl S-300 HR. The results of SDS-PAGE suggested that purified collagen from S. japonicus was a 1α trimer (about 135 kDa) while 1α chain resembling α1 chain of type I collagen of vertebrate. The thermal stability temperature (Ts) was 57.0 °C as measured by DSC, about 5.0 °C lower than that of type I collagen of calf. Peptide mapping and amino acid analysis of PSC also revealed the difference between invertebrate and vertebrate. However, the presence of (α1)3 trimers was evident.