一株地衣芽孢杆菌产凝乳酶酶学性质研究

摘要

[Objective] To study the properties of chymosin from Bacillusli cheniformis.[Method] Determination of the relative enzyme activity of chymosin which acted in different temperatures.pH,concentration of substrate and metal ions.[Result] The optimum curd temperature of chymosin vas 70℃,but the activity would lost over 40℃ and would lost all over 75℃ by heat treatment for 10 min.The optimum pH was 5 ～ 8 and the most stable pH was 7,the activity of chymosin would increase with the decreace of pH.Ca2+,Fe2+,Fe3+,Mn2+,Mg2+,A13+ promoted the activity of Chynosin and Li2+,Na2+,Cu2+,Zn2+ had inhibition effect.The optimum substrate concentration was 250 g/L and the Ca2+ was 0.014 g/L.%目的:对地衣芽孢杆菌所产凝乳酶的酶学特性进行研究.方法:在不同的温度、pH值、底物浓度、不同金属离子等条件下测定地衣芽孢杆菌产凝乳酶相对酶活力.结果:地衣芽孢杆菌所产凝乳酶最适凝乳温度为70℃;40℃以上热处理后凝乳活性有不同程度的损失,75℃热处理10min后凝乳酶活性丧失;pH值为5～8时凝乳活性随乳pH值的降低而增强,pH值为7时凝乳酶最稳定;Ca2+、Fe2、Fe3、Mn2、Mg2、Al3+对酶活性有一定的促进作用;Li2+、Na+、Cu2+、Zn2对酶活性有抑制作用;底物浓度最适为250 g/L、Ca2+的最适浓度为0.014 g/L.