一株Kluyveromyces lactis酵母胞内乳糖酶性质的研究

Properties of the lactase isolated from Kluyveromyces lactis

源自乳酸克鲁维酵母的β-半乳糖苷酶为胞内酶,其具有乳糖水解能力和半乳糖苷的转移作用。本实验运用单因素试验方法研究乳酸克鲁维酵母乳糖酶的性质。结果表明该酶在pH值为6.0~7.0和37℃~48℃间比较稳定,酶作用最适pH值在6.5,最适反应温度为43℃,Mn2＋、Mg2＋等对酶有明显的激活作用,而Zn2＋、Cu2＋等对酶活有抑制作用。该酶以ONPG底物的米氏常数为4.186mmol/L。

β-galactosidase derived from Kluyveromyces lactis is a cytosolic enzyme,which can hydrolyze lactose into galactose and glucose and transfer galactoside.Properties of lactase isolated from K.lactis were investigated using single-factor experiment design.The results showed that the optimal pH and temperature of the lactase were 6.5 and at 43℃,respectively.The lactase was found high stability in the range of pH 6.0~7.0 and temperature 37℃~48℃.And the enzyme was significantly activated by the metal ions of Mn2＋ and Mg2＋.Additionally,the enzyme was inhibited by the metal ions of Zn2＋ and Cu2＋.Km value of the lactase was 4.186mmol/L of ONPG.