Isolation and characterization of acid and pepsin-solubilized collagens from the skin of balloon fish (Diodon holocanthus)

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were successfully extracted from the skin of balloon fish (Diodon holocanthus) with yields of 4% and 19.5% respectively (based on dry weight). According to the electrophoretic patterns, both the ASC and PSC consisted of two different alpha chains (alpha 1 and alpha 2), were characterized to be type I, and contained imino acid of 179 and 175 residues/1000 residues, respectively. The PSC had a lower content of high-molecular weight cross-links than the ASC. The ultraviolet (UV) absorption spectrum of collagens showed that the distinct absorption was between 210 and 230 nm. A maximum solubility in 0.5 M acetic acid was observed at pH 1-5, and a sharp decrease in solubility above 4% (w/v) in both the ASC and PSC was observed in the presence of NaCl. The denaturation temperatures (T-d) of the ASC and PSC measured by viscometry were 29.01 degrees C and 30.01 degrees C, respectively. The maximum temperatures (T-max) of the ASC and PSC were 29.64 degrees C and 30.30 degrees C, respectively. (C) 2011 Elsevier Ltd. All rights reserved.