中文摘要：

利用热水抽提法提取鲨鱼皮明胶,控制酶法水解条件制备天然抗冻多肽.以细菌低温保护活性为指标,筛选蛋白水解酶种类及酶解时间,利用Sephadex G-50凝胶过滤色谱、SP-Sephadex C-25强阳离子交换色谱等分离手段进行分离,得到细菌低温保护高活性组分.结果表明,酶解鲨鱼皮明胶得到高活性抗冻多肽的最适蛋白水解酶为酸性蛋白酶,酶解温度50℃、pH 3.0、酶/底物3 000 U·g-1、底物浓度3%、酶解时间1 h;经过Sephadex G-50凝胶过滤色谱、SP-Sephadex C-25强阳离子交换色谱等分离手段得到阳离子的P2组分,经过细菌低温保护测试,当浓度为500μg·mL-1时,大肠杆菌的存活率达到80.8%.分离得到的抗冻多肽具有较高的抗冻活性,可望应用于食品、医药等产业中.

英文摘要：

The gelatin of shark skin was extracted by hot water. The most appropriate protease and hy- drolysis time were selected with the index of hypothermia protection activity on bacteria. Then the hydrolyzate was added on to Sephadex G- 50 gel filtration chromatography and SPSephadex C -25 strong cation exchange chromatography to acquire high activity fractions. The results indicated that the most appropriate protease is acid protease, and the hydrolysis condition is as follows, hydrolysis temperature 50℃, pH 3.0, proportion of acid protease to substratum 3 000 U · g- 1 per substratum, substratum concentration 3%, hydrolysis time 1 h. The cationic fraction termed P2 shows higher antifreeze activity after Sephadex G - 50 gel filtration chromatography and SP - Sephadex C - 25 strong cation exchange chromatography. The hypothermia protection assay shows that the survival rate of E. coli was 80.8% when the concentration of peptide complexes was 500 μg·mL-1. The antifreeze peptides obtained after isolation shows higher antifreeze activity, and can be applied into food and medicine industry.