一株嗜酸乳杆菌突变株亚油酸异构酶的纯化及性质

亚油酸异构酶可以把亚油酸转化为共轭亚油酸。用硫酸铵沉淀、透析、凝胶过滤等步骤 ,从 1株嗜酸乳杆菌突变株中分离纯化了该酶。纯化倍数为 5 2 .0倍、比活力达 5 1 3 .0U/mg、活力回收 7.0 %。用SDS PAGE测得该酶亚基的分子量为 40 .7ku ;该酶的最适反应pH值为 4.0左右 ,最适反应温度为 3 0～ 40℃ ,在 pH 2 .0～ 7.0和 60℃以下较稳定。Fe2 + 、Mg2 + 、Zn2 + 、Na+ 能提高酶活性 ,Hg2 + 、Cu2 + 、Mn2 + 、Fe3+ 能抑制酶活性。以亚油酸为底物时该酶的动力学常数为 2 1 .6mmol/L。

Purification and Characterization of Linoleate Isomerase from Lactobacillus acidophilus

Linoleate isomerase can convert linoleic acid into conjugated linoleic acid. The linoleate isomerase was purified from a Lactobacillus acidophilus mutant by (NH 4) 2SO 4 fractionation,dialysis and Sephadex G-100 gel filtration chromatography. The enzyme was considered to be electrophoretic pure. Purity of 52.0-fold and an overall yield of 7.0% was achived. The specific activity of the purified enzyme was 513.0U/mg. The relative molecular weight of the enzyme subunit was about 40.7 ku by SDS-PAGE. The enzyme had an optimum reaction temperature of 30～40℃ and pH of 4.0, respectively. The activity of the enzyme was stable under 60℃ with the pH range of 2.0～7.0. With ion concentration of 1*#mmol/L, the activity of enzyme could be activated by Fe 2+ , Mg 2+ , Zn 2+ and Na +, while inhibited by Hg 2+ , Cu 2+ , Mn 2+ and Fe 3+ . The apparent K m of the enzyme was 21.6*#mmol/L, and the V max was 7.14*#mmol/(L·h).