Preparation, isolation and hypothermia protection activity of antifreeze peptides from shark skin collagen

Antifreeze proteins have characteristics of inhibiting the growth of crystals, decreasing the injury of cells and can retain the structure, texture and quality of productions. The purpose of this study is to obtain natural, safe, high activity antifreeze peptides using various separating means, and to detect their hypothermia protect activity on Lactobacillus bulgaricus. Collagen derived from shark skin was hydrolyzed with Acid Protease. Then the hydrolysate was subsequently added on to SP-Sephadex C-25 column, Sephadex G-50 gel filtration column and C18 Reversed-phase high performance liquid chromatography to acquire a pure component. A purified hydrophilic peptide, named SsC-AFP, with the characteristic of pI < 5.0 and molecular weight of 906 Da, was obtained. The amino acid sequence of SsC-AFP was GAIGPAGPLGP, which consisted of Gly–Pro–x tripeptide repeat sequence. When the concentration of SsC-AFP was 250 μg/mL, the survival rate of L. bulgaricus was up to 90.28%.