Novel Nano-/Micro-Biocatalyst: Soybean Epoxide Hydrolase Immobilized on UiO-66-NH2 MOF for Efficient Biosynthesis of Enantiopure (R)-1, 2-Octanediol in Deep Eutectic Solvents

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• 作者：Shi-Lin Cao ; Dong-Mei Yue ; Xue-Hui Li ; Thomas J. Smith ; Ning Li ; Min-Hua Zong ; Hong Wu ; Yong-Zheng Ma ; Wen-Yong Lou
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2016
• 出版时间：June 6, 2016
• 年：2016
• 卷：4
• 期：6
• 页码：3586-3595
• 全文大小：688K
• 年卷期：0
• ISSN：2168-0485

文摘

The nano-/microscale UiO-66-NH₂ metal–organic framework (MOF) materials were successfully prepared with a uniform size of about 350–400 nm and structurally characterized. Soybean epoxide hydrolase (SEH), a useful hydrolase for synthesis of valuable vicinal diols, was for the first time efficiently immobilized onto the prepared UiO-66-NH₂ MOF. The resulting novel nano-/microbiocatalyst SEH@UiO-66-NH₂ manifested high SEH loading (87.3 mg/g) and enzyme activity recovery (88.0%). The novel SEH@UiO-66-NH₂ greatly surpassed the free SEH with resepct to pH stability, thermostability, and tolerance to organic solvents. SEH@UiO-66-NH₂ retained more than 17.6 U activity after 2 h of incubation at 45 °C, whereas free SEH maintained around 10.1 U activity under the same conditions. After storage at 4 °C for 4 weeks, the prepared SEH@UiO-66-NH₂ still retained around 97.5% of its initial activity. The significant enhancements resulted from the increase of structural rigidity of SEH@UiO-66-NH₂, which was demonstrated by the secondary structure analysis of the enzyme. The optimun pH and tempearture of SEH@UiO-66-NH₂ were significantly superior to the corresponding levels of its free counterpart. Also, SEH@UiO-66-NH₂ manifested markedly enhanced enzyme–substrate affinity and catalytic efficiency compared to free SEH, as supported by a lower apparent K_m value (6.5 vs 19.2 mM) and an increased V_max/K_m value (8.0 × 10^–3 vs 5.8 × 10^–3 min^–1), respectively. Furthermore, the as-prepared SEH@UiO-66-NH₂, for the first time, was successfully applied as an efficient biocatalyst for the asymmetric hydrolysis of 1,2-epoxyoctane to (R)-1,2-octanediol in a novel deep eutectic solvent (DES) with a yield of around 41.4% and a product e.e. value of 81.2%. Remarkably, the nano-/microscale UiO-66-NH₂ MOFs as novel enzyme support materials are promising for enzyme immobilization, and the prepared SEH@UiO-66-NH₂ exhibited great potential for efficient biosynthesis of enantipure (R)-1,2-octanediol.