二氧化硅纳米材料固定中性脂肪酶的条件优化及其特性

Optimize conditions and activities for neutrophil lipase immobilized by nano-silica dioxide

摘要:

以二氧化硅纳米材料为载体, 采用吸附法对脂肪酶进行固定化, 研究了不同条件对固定化脂肪酶的催化活性的影响, 得到最佳的固定化条件: 给酶量为28 300 U/g, 固定化温度为45oC, pH值为7.5, 时间为10 h, 此时固定化酶的活力约为3867 U/g载体。固定化酶的最适反应温度为45oC, 比游离酶的反应温度高5oC, 最适pH下降到5.5, 低于游离酶的反应pH(pH 7)。固定化酶的热稳定性和pH稳定性较游离酶有了很大的提高, 其在70 oC以下能保持70%以上的酶活力, 而游离酶在50 oC下残余酶活力仅为30%。在pH 5~8的范围内, 固定化酶的酶活力能保持50%以上, 而游离酶只能保持20%左右。用固定化的中性脂肪酶催化不同的油品, 即大豆油、菜籽油及泔水油生产生物柴油, 菜籽油的酯化率最高。

Abstract:

We used adsorption method to immobilize the lipase by using nano-silica dioxide as the carrier. And we also studied different immobilization conditions effects on the catalytic activity. We got optimize immobilization conditions which were as follow the lipase quantity of 28 300 U/g, temperature of 45oC, pH of 7.5 and treated for 10 h. Under these conditions the immobilized lipase activity yield 3867 U/g carrier. The best reactive temperature for immobilized lipase was 45oC and higher than 5oC for free enzyme, and the optimal pH dropped to 5.5 compared that of free enzyme (pH 7.0). The immobilized lipase stability for thermal and pH are improved than free lipase. When temperature was below 70oC the immobilized enzyme activity was over 70% than initial activity. The free lipase activity just kept original 30% at 50°C. When pH was 5–8, the immobilized lipase activity was still more than 50% and the free lipase only remained 20%. When we used the immobilized neutrophil lipase catalyzing different oil to produce biodiesel such as soybean oil, rapeseed oil and waste oil, the esterification rate of rapeseed oil was the highest.