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
a chains (a1 and a2), 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 1e5, 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 (Td) of the ASC and PSC measured by viscometry were 29.01 C and
30.01 C, respectively. The maximum temperatures (Tmax) of the ASC and PSC were 29.64 C and 30.30 C,
respectively.