蓝圆鲹肌肉组织蛋白酶B的纯化与性质分析

Purification and characterization of cathepsin B from the skeletal muscle of blue scad(Decapterus maruadsi)

在鱼糜制品生产过程中,凝胶劣化现象是引起鱼糜品质下降的重要原因。研究表明,溶酶体中的内源性组织蛋白酶B会促进肌原纤维蛋白的降解,进而导致鱼糜凝胶劣化。迄今为止,多种鱼体肌肉中的组织蛋白酶B已有研究,但海水经济低值鱼蓝圆鲹中该酶的情况却尚未报道。本研究采用硫酸铵沉淀和柱层析相结合的方法,从蓝圆鲹肌肉中分离纯化得到分子量约为27ku的组织蛋白酶B。酶学性质结果显示,该酶最适温度和最适pH分别为55℃和5.5,半胱氨酸蛋白酶抑制剂E-64能有效抑制其活性。对肌原纤维蛋白的降解实验表明,在最适条件下,蓝圆鲹组织蛋白酶B对肌原纤维蛋白有一定的降解作用。因此,组织蛋白酶B参与肌原纤维蛋白的降解,更可能参与在低pH条件下鱼糜凝胶劣化。

During the manufacturing process of surimi,the modori phenomenon was an important factor that affected the final quality of the products.According to current studies,cathepsin B in the lysosome played a significant role in the degradation of myofibillar proteins.Cathepsin B in the muscle of various species of fish had been investigated.However,cathepsin B in marine fish blue scad（Decapterus maruadsi）was infrequently reported.In the present study,cathepsin B was purified by ammonium sulfate precipitation and a series of column chromatographies.SDS-PAGE showed that the molecular mass of the purified enzyme was about 27ku.The optimal temperature and pH of the enzyme were 55℃ and 5.5,respectively.Cathepsin B was effectively inhibited by cysteine proteinase inhibitor E-64.Under optimal conditions,cathepsin B could promote the degradation of myofibrillar proteins.Therefore,cathepsin B might participate in not only degradation of myofibrillar proteins,but also modori at acidic pH range.