Isolation and characterization of collagens from the skin of giant grouper (Epinephelus lanceolatus)

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin of giant groupers (Epinephelus lanceolatus) with yields of 39.51 and 19.12%, respectively. ASC and PSC consisted of two different chains (1 and 2) and were characterized to be type I collagen with no disulfide bond. The imino acid contents of the ASC and PSC from giant grouper skin were 189 and 181 per 1,000 residues, respectively. The maximum endothermic temperatures (T-max) of ASC and PSC measured by differential scanning calorimetry (DSC) were 31.71 and 31.33 degrees C, respectively. The denaturation temperatures of ASC and PSC measured by viscometry were 29.84 and 29.05 degrees C, respectively. The maximum solubility in 0.5 M acetic acid was observed at pH 5 and pH 6 for ASC and PSC, respectively. A sharp decrease in solubility was observed for both ASC and PSC in the presence of NaCl above 3% (w/v).