Abstract: In this paper, the characteristics of pepsin-soluble collagen from the body wall of Stichopus japonicus (sjPSC) and the skin of Oreochromis niloticus (onPSC) were comparatively studied. The results showed that ultraviolet and Fourier transform-infrared spectroscopic measurements of onPSC and sjPSC were quite similar. Both PSCs contained mainly α- and β-chains as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The electrophoretic patterns of these two collagens under non-reducing and reducing conditions were quite similar, suggesting that reduction of disulfide bonds did not occur in these two collagens. Glycine was the dominant amino acid in both sjPSC and onPSC, accounting for approximately (344.57 ± 2.16)‰ and (353.00 ± 4.84)‰ of the total amino acid residues, respectively. More glutamic acid, aspartic acid, serine, valine, isoleucine and tyrosine were observed in sjPSC when compared with onPSC (P < 0.05). However, more L-hydroxy proline, L-proline, leucine, phenylalanine, histidine and lysine were observed in onPSC (P < 0.05). Peptide maps of both PSCs digested by V8 and α-chymotrypsin were completely different, suggesting some differences in their structure, especially in terms of glutamic acid, aspartic acid and hydroxyproline residues.

Key words: pepsin-soluble collagen, Stichopus japonicus, Oreochromis niloticus, amino acid, structure