蓝圆鲹肌肉组织蛋白酶B的纯化与性质分析

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。 

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

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.