Department of Biological Engineering, Beijing University of Chemical Technology, Beijing, China.
Department of Biological Engineering, Beijing University of Chemical Technology, Beijing, China.
Colloids Surf B Biointerfaces. 2023 Nov;231:113541. doi: 10.1016/j.colsurfb.2023.113541. Epub 2023 Sep 13.
The three enzymes galactose oxidase (GO), catalase (CAT), and Mn-superoxide dismutase (SOD) were simultaneously immobilized by coordinating to Cu in phosphate buffer saline. The biocatalyst GO&CAT&SOD@Cu was used for the conversion of 5-hydroxymethylfurfural (HMF). The immobilized GO catalyzes the oxidation of HMF to 2,5-diformylfuran (DFF), concomitantly the co-substrate O is reduced to hydrogen peroxide (HO). A portion of the byproduct HO is broken down to O and HO by the co-immobilized CAT, and the evolved O can be recycled and used as the co-substrate. A portion of the byproduct HO is broken down to produce hydroxyl radicals •OH under the synergistic catalysis of the immobilized SOD and coordinated Cu, and the produced •OH can reactivate the immobilized galactose oxidase. Two aspects contribute to the high catalytic efficiency by GO&CAT&SOD@Cu: the reactivation of the immobilized galactose oxidase by producing •OH and the enrichment of the co-substate O by recycling the produced O. For the conversion of 10 mM HMF, GO&CAT&SOD@Cu (with encapsulated GO 0.2 mg/mL) achieved 97% HMF conversion within 2 h reaction. In contrast, free galactose oxidase M variant (ACS Catalysis 2018, 8, 4025) (0.2 mg/mL) achieved 25.3% HMF conversion within 2 h reaction. All the reactions were carried out in pure water, not in PBS.
三种酶——半乳糖氧化酶（GO）、过氧化氢酶（CAT）和锰超氧化物歧化酶（SOD）通过与磷酸盐缓冲盐水（PBS）中的 Cu 配位，同时被固定化。所得固定化酶 GO&CAT&SOD@Cu 被用于 5-羟甲基糠醛（HMF）的转化。固定化 GO 催化 HMF 氧化生成 2,5-二羟甲基呋喃（DFF），同时将共底物 O 还原为过氧化氢（HO）。一部分副产物 HO 在共固定化 CAT 的作用下分解为 O 和 HO，而产生的 O 可以被回收并重新用作共底物。一部分副产物 HO 在固定化 SOD 和配位的 Cu 的协同催化作用下，生成羟基自由基 •OH，所产生的 •OH 可以使固定化半乳糖氧化酶重新激活。GO&CAT&SOD@Cu 具有很高的催化效率，主要有两个方面的原因：一是通过产生 •OH 使固定化半乳糖氧化酶重新激活；二是通过回收产生的 O 来富集共底物 O。对于 10 mM HMF 的转化，在 2 小时的反应时间内，含 0.2 mg/mL 包埋 GO 的 GO&CAT&SOD@Cu 实现了 97%的 HMF 转化率。相比之下，游离半乳糖氧化酶 M 变体（ACS Catalysis 2018, 8, 4025）（0.2 mg/mL）在 2 小时的反应时间内仅实现了 25.3%的 HMF 转化率。所有反应均在纯水中进行，而不是在 PBS 中进行。
