蓝圆鲹肌肉中丝氨酸蛋白酶的分离纯化及性质研究

鱼类死后肌肉容易发生软化现象。研究表明,这与肌肉中的丝氨酸蛋白酶有着密切的关系。本研究通过硫酸铵盐析、DEAE-Sephacel、Q-Sepharose及Capto Q等柱层析相结合的方法,从蓝圆鲹肌肉中纯化得到一种具有分解明胶能力的丝氨酸蛋白酶,SDS-PAGE结果显示其分子量约为60ku,该酶最适温度及最适pH分别为40℃和9.0。丝氨酸蛋白酶抑制剂Pefabloc SC、Benzamidine、MBTI、PMSF和LBTI均能明显的抑制该酶的活性,而其他蛋白酶抑制剂对其活性没有明显的影响。底物特异性表明其能有效的降解丝氨酸蛋白酶荧光底物Boc-Leu-Lys-Arg-MCA,但进一步研究发现,该酶对I型胶原蛋白及明胶有明显的分解能力,同时对肌球蛋白重链也有一定的分解作用,说明该酶可能参与鱼肉保鲜中肌肉软化的过程。

Study on purification and characterization of a serine proteinase from the skeletal muscle of blue scad(Decapterus maruadsi)

Some researches revealed that the tenderization of fish muscle during postmortem was caused by the endogenous proteinase especially serine proteinase.A collagenolytic serine proteinase was purified from blue scad skeletal muscle to homogeneity by ammonium sulfate fractionation and chromatographies including DEAE-Sephacel,Q-Sepharose and Capto Q.The molecular weight of the enzyme was 60ku as detected by SDS-PAGE.The optimal pH and temperature of the purified enzyme were 9.0 and 40℃,respectively.The enzyme activity was inhibited by serine proteinase inhibitors such as Pefabloc SC,Benzamidine,MBTI,PMSF and LBTI.However,other proteinase inhibitors had no effect on serine proteinase.Substrate specificity experiment demonstrated that the enzyme showed high specificity towards Boc-Leu-Lys-Arg-MCA.Furthermore,the enzyme effectively hydrolyzed gelatin,native type-I collagen and myofibrillar proteins such as myosin heavy chain(MHC),these datum suggested that this enzyme might play an important role during postmortem tenderization of fish muscle.