Isolation and structural characterisation of acid- and pepsin-soluble collagen from the skin of squid Sepioteuthis lessoniana (Lesson, 1830).

Acid-solubilised collagen (ASC) and pepsin-solubilised collagen (PSC) were effectively isolated from squid skin with good yield and total protein content. ASC and PSC consist of two α-chains with an imino acid content of 182.6 and 184 imino acid residues/1000 residues. The molecular weight was determined to be between 73 and 107 kDa by using SDS-PAGE. For peptide mapping, collagens were digested with achromo endopeptidase, and all components, including α, β-chains, were markedly hydrolysed. Degradation peptides with molecular weights between 106.9 and 15.47 kDa were obtained. UV-vis absorption spectrum revealed distinct absorption at 220-240 nm. FT-IR spectra of collagens were almost similar when compared with standard. In differential scanning calorimetry profile, ASC and PSC exhibited a To of 59.10, 62.18°C and TP of 104.91, 98.10 °C, respectively. This investigation indicates that the collagen isolated from the squid skin, which is thrown as waste in the seafood-processing plant, might supplement the vertebrate collagen in industrial applications.