School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
Appl Biochem Biotechnol. 2020 Sep;192(1):132-145. doi: 10.1007/s12010-020-03268-z. Epub 2020 Apr 22.
Covalent immobilization of lipase onto a solid carrier is an effective way to enhance stability. Immobilization inhibits the activity of lipase due to decreased flexibility of enzyme structure via the covalent bond. In this study, monomer of the metal-organic frameworks (MOFs) material ZIF-8 (2-methyl imidazole-4-carboxylic acid) was innovatively used as a chemical modifier of Candida nrugosa lipase (CRL). The circular dichroism spectra results show that the CRL molecule was altered by chemical modification and thus its catalytic activity was 1.3 times higher than that of the free CRL. The modified CRL molecule was further immobilized in the "skeleton" of ZIF-8 through the monomer while in situ forming the cell skeleton of the MOFs, which prevent the active center from being destroyed. The results show that conjugation of chemical modification and immobilized enzymes ensure that there was no obvious reduction in the activity of CRL after immobilization and the stability of CRL was improved. Especially, the organic solvent stability of the modified immobilization CRL in isopropanol was significantly improved and retained more than 148% of its activity.
将脂肪酶通过共价键固定在固体载体上是一种提高稳定性的有效方法。固定化由于酶结构的柔韧性降低而抑制脂肪酶的活性。在这项研究中，金属有机骨架（MOFs）材料 ZIF-8（2-甲基咪唑-4-羧酸）的单体被创新性地用作假丝酵母脂肪酶（CRL）的化学修饰剂。圆二色光谱结果表明，CRL 分子通过化学修饰发生了改变，因此其催化活性比游离 CRL 提高了 1.3 倍。然后，通过单体将改性的 CRL 分子进一步固定在 ZIF-8 的“骨架”中，同时原位形成 MOFs 的细胞骨架，从而防止活性中心被破坏。结果表明，化学修饰和固定化酶的结合确保了 CRL 固定化后活性没有明显降低，并且提高了 CRL 的稳定性。特别是，改性固定化 CRL 在异丙醇中的有机溶剂稳定性得到了显著提高，保留了其活性的 148%以上。
