Xylanase immobilization onto trichlorotriazine-functionalized polyethylene glycol grafted magnetic nanoparticles: A thermostable and robust nanobiocatalyst for fruit juice clarification
Xylanase immobilization onto trichlorotriazine-functionalized polyethylene glycol grafted magnetic nanoparticles: A thermostable and robust nanobiocatalyst for fruit juice clarification
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DOI：
10.1016/j.ijbiomac.2020.06.273
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发表时间：
2020-11-15
影响因子：
8.2
通讯作者：
Varma, Rajender S.
中科院分区：
文献类型：
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作者：
Kharazmi, Sara;Taheri-Kafrani, Asghar;Varma, Rajender S.
将木聚糖酶共价固定在三氯三嗪功能化的聚乙二醇接枝磁性纳米粒子上，制备了具有更高催化活性和稳定性的木聚糖酶。部署了几种工具来监测合成和固定化过程，纳米载体的负载能力，以及纳米生物催化剂的结构/化学特性。在25 ℃、pH 6.5的20 mM磷酸盐缓冲液中，木聚糖酶的最佳固定化产率为260 mg木聚糖酶/g纳米载体。固定化后，木聚糖酶的最适pH（6.5 ~ 7.5）和最适温度（60 ~ 70 ℃）发生了前移，最大活力（v（max））增加（2.69 ~ 6.01 U/mL），酶活力（E-a）降低（14.61 ~ 13.41 kJ/mol），表明固定化酶在高温和pH条件下的性能得到了提高。固定后记录到Km从25.51 mg/mL增加至40.42 mg/mL。结果表明，固定化木聚糖酶的热稳定性得到了提高。值得注意的是，它显示出良好的可重复使用性，如通过在50 ℃，pH 4.5下孵育120分钟后在菠萝汁澄清的富集中9次循环后保留其初始活性的50%所验证的。结构分析揭示了几次循环后酶的α-螺旋和β-折叠含量的一些部分变化。(C)2020爱思唯尔B. V.保留所有权利。
The covalent immobilization of xylanase onto the trichlorotriazine-functionalized polyethylene glycol grafted magnetic nanoparticles was exploited to generate a stabilized xylanase with improved catalytic activity and stability. Several tools were deployed to monitor the synthesis and immobilization processes, the loading capacity of nanocarrier, and the structural/chemical characteristics of the nanobiocatalyst. The optimum immobilization yield of xylanase was 260 mg xylanase/g nanocarrier in 20 mM phosphate buffer, pH 6.5 at 25 degrees C. A forward shift in optimum pH (6.5 to 7.5) and temperature (60 to 70 degrees C) of xylanase was observed after immobilization and the performance of immobilized enzyme was improved at high temperatures and pHs as affirmed by enhancement of v(max) (2.69 to 6.01 U/mL) and decreases of E-a (14.61 to 13.41 kJ/mol). An increase in K-m from 25.51 to 40.42 mg/mL was recorded after immobilization. The obtained results indicated augmented thermal stability of the immobilized xylanase. Notably, it showed good reusability as validated by retention of 50% of its initial activity after nine recycles in enrichment of the pineapple juice clarification after 120 min incubation at 50 degrees C, pH 4.5. The structural analysis revealed some partial changes in the alpha-helix and beta-sheet content of the enzyme after several recycles. (C) 2020 Elsevier B.V. All rights reserved.