酶水解苦味肽对大黄鱼白细胞与溶菌酶活性的影响

Effect of enzymatic hydrolysis of bitter peptide on white blood cell and lysozyme activity of Larimichthys crocea

目的探究酶水解苦味肽对大黄鱼白细胞与溶菌酶活性的影响。方法分别利用木瓜蛋白酶、胰蛋白酶、胃蛋白酶,碱性蛋白酶和风味蛋白酶酶解鮸鱼鱼肉制备苦味最高的苦味肽。以幼大黄鱼为实验对象,分别设置4个不同的组(对照组、低剂量组、中剂量组、高剂量组),对其进行腹腔注射苦味肽,观察8周后采血检测,以白细胞/总血细胞的平均比率和溶菌酶活性为指标评价苦味肽对大黄鱼先天免疫系统的作用效果。结果胃蛋白酶水解产生的苦味肽苦味最高。对照组的白细胞/总血细胞的平均比率为14.6%,低剂量组(0.6 mg/鱼)为28.86%,中剂量组(1.2 mg/鱼)为35%,高剂量组(2.4 mg/鱼)为29.3%。在白细胞对乳胶颗粒的体外吞噬作用实验中,对照组与测试组的吞噬指数分别为1.15(0mg/L),1.88(0.4mg/L),3.84(0.8mg/L),5.94(1.2mg/L)。溶菌酶在60min内的相对裂解活性分别为0.17、0.101、0.307和0.198。与对照组相比苦味肽可以提高大黄鱼的免疫力,当注射剂量为1.2mg时,吞噬与溶菌酶活性都显著升高,可初步确定最佳注射剂量为1.2mg。结论苦味肽可以通过多途径有效地提高天然免疫的作用,可以降低大黄鱼疾病的发生,值得进一步研究。

Objective To study the effect of enzymatic hydrolysis of bitter peptide on leukocyte and lysozyme activity of Larimichthys crocea. Methods The bitter peptide with the highest bitter taste was prepared by digesting Michthysmiiuy with papain, trypsin, pepsin, alkaline protease and flavor protease. Taking the young yellow croaker as the experimental object, 4 different groups were set(control group, low dose group, medium dose group, high dose group). The bitter peptides were injected into the large yellow croaker by intraperitoneal injection. Blood was collected and dectected after 8 weeks for observation. The effect of bitter peptide on the innate immune system of large yellow croaker was evaluated by the average ratio of white blood cells/total blood cells and lysozyme activity.Results The bitter peptide produced by pepsin hydrolysis had the highest bitter taste. The average ratio of leukocytes/total blood cells in the control group was 14.6%, the low dose group(0.6 mg/fish) was 28.86%, the middle dose group(1.2 mg/fish) was 35%, and high dose group(2.4 mg/fish) was 29.3%. In the in vitro phagocytosis of leukocytes against latex particles, the phagocytic index of the control group and the test group were 1.15(0 mg/L), 1.88(0.4 mg/L), 3.84(0.8 mg/L), 5.94(1.2 mg/L), respectively. The relative lytic activities of lysozyme in 60 min were 0.17, 0.101, 0.307 and 0.198, respectively. Compared with the control group, bitter peptide could improve the immunity of large yellow croaker. When the dose was 1.2 mg, both phagocytosis and lysozyme activity were significantly increased, and the optimal injection dose was 1.2 mg. Conclusion Bitter peptide can effectively improve the role of natural immunity through multiple ways, and can reduce the occurrence of disease in large yellow croaker, which deserves further study.