Isolation and Characterization of Collagen from the Body Wall of Sea Cucumber Stichopus monotuberculatus

Abstract To exploit a new collagen resource from the body wall of tropical sea cucumber, pepsin‐solubilized collagen of Stichopus monotuberculatus (PSC‐Sm) was isolated and characterized with UV‐vis spectra, sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), amino acid composition, enzyme‐digested peptide maps, Fourier transform infrared spectroscopy (FTIR), maximum transition temperature ( T m ), and solubilities. The maximum absorbance of PSC‐Sm was exhibited at 218 nm in UV‐vis spectra. The triple helical structure and activity of PSC‐Sm could be indicated by FTIR. SDS‐PAGE showed that the triple helix of PSC‐Sm was formed as (α 1 ) 3 by 3 α 1 chain homologous with molecular weight of 137 kDa. The T m of PSC‐Sm and calf skin collagen (CSC) were 30.2 and 35.0 ºC, respectively, which consistent with the result of FTIR that CSC contained more stable triple‐helix than PSC‐Sm. Peptide maps were different between PSC‐Sm and CSC, indicating the differences in their amino acid compositions and sequences. The maximum and minimum solubilities of PSC‐Sm were observed at pH 2.0 and 4.0, respectively. A sharp decrease in solubility appeared when NaCl concentration was between 3% and 5%. These results showed that collagen from S. monotuberculatus had the type I collagen characteristics and good thermal stability, and therefore, it could be used as an alternative resource of collagen.