Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Ministry of Agriculture Key Laboratory of Oil Crops Biology, Wuhan 430062, China.
Bioresour Technol. 2012 Jul;115:141-6. doi: 10.1016/j.biortech.2011.11.128. Epub 2011 Dec 20.
In this work, mixed-mode silica particles functionalized with octyl and sulfonic acid groups was conveniently prepared by co-bonding a mixture of n-octyltriethoxysilane and 3-mercaptopropyltriethoxysilane and then oxidized with hydrogen peroxide. Candida rugosa lipase (CRL) was immobilized on the mixed-mode silica particles via hydrophobic and strong cation-exchange interaction. The resulting immobilized CRL increased remarkably its stability at high temperature in comparison to free CRL. The immobilized CRL was used as biocatalysts for enzymatic esterification of phytosterols with free fatty acids (FFAs) to produce phytosterol esters. The phytosterols linolenate esterification degree of 95.3% was obtained under the optimized condition. Phytosterols esters could also been converted in high yields to the corresponding long-chain acyl esters via transesterification with methyl esters of fatty acids (80.5%) or triacylglycerols (above 95.5%) using mixed-mode silica particles immobilized CRL as biocatalyst. Furthermore, the immobilized CRL by absorption retained 78.6% of their initial activity after 7 recycles.
在这项工作中，通过共键合混合物 n-辛基三乙氧基硅烷和 3-巯丙基三乙氧基硅烷，然后用双氧水氧化，方便地制备了同时具有辛基和磺酸基团的混合模式硅胶颗粒。固定化脂肪酶通过疏水和亲电相互作用固定在混合模式硅胶颗粒上。与游离脂肪酶相比，固定化脂肪酶在高温下的稳定性显著提高。固定化脂肪酶被用作生物催化剂，用于植物甾醇与游离脂肪酸（FFAs）的酶酯化反应，以生产植物甾醇酯。在优化条件下，得到了亚麻酸酯化度为 95.3%的植物甾醇酯。通过使用混合模式硅胶颗粒固定化脂肪酶作为生物催化剂，通过与脂肪酸甲酯（80.5%）或三酰基甘油（高于 95.5%）进行酯交换，也可以以高收率将植物甾醇酯转化为相应的长链酰基酯。此外，通过吸收固定化的脂肪酶在 7 次循环后保留了其初始活性的 78.6%。
