Abstract：
The biocatalysts are broadly explored in the biological transformation processes. The enzyme cascade catalysis involves various catalytic activities in a sequential process to produce the desired product including the formation of reaction intermediates. Enzyme immobilization is a method in which enzymes are confined within a support or matrix either physically or chemically to enhance their relative stability and catalytic activity in the enzyme cascade catalysis. In view of this, L-arabinose isomerase (L-AI) and L-ribose isomerase (L-RI) were immobilized on zeolite based metal framework as a micro-composite construct (DEMC@L-AI+L-RI) using linker, and metal ions. Such immobilization could be of great significance and provide several advantages like mesoporous surface for enzyme adsorption, desirable functionality in the production of products in enzyme cascade reaction, high storage stability and enhanced recyclability. The developed DEMC@L-AI+L-RI was characterized using SEM, FTIR, CLSM and TGA. The immobilization yield was 32% and loading of enzyme was 22% on the surface of micro-composite. The DEMC@L-AI+L-RI showed relatively stable catalytic activity at pH 5-6 and temperature 40 °C. The catalytic efficiency (kcat/Km) of both the enzymes was increased by 1.5-fold after immobilization. With the immobilized biocatalyst, bioconversion of L-arabinose to L-ribose was 22.6% and D-galactose to D-talose was 15.2%. The reusability of developed biocatalyst for more than six cycles was observed for more than 50% yield of the sugars. The conversion of biomass sugars from beetroot and onion waste residues was 20% and 14% to produce ribose and talose, respectively.
摘要：
在生物转化过程中对生物催化剂进行了广泛的探索。酶级联催化在连续过程中涉及各种催化活性以产生所需产物,包括形成反应中间体。酶固定化是一种方法,其中酶被物理地或化学地限制在支持物或基质内以增强它们在酶级联催化中的相对稳定性和催化活性。鉴于此,使用接头将L-阿拉伯糖异构酶（L-AI）和L-核糖异构酶（L-RI）固定在基于沸石的金属框架上，作为微复合构建体（DEMC@L-AIL-RI），和金属离子。这种固定可能具有重要意义，并提供了一些优势，如介孔表面的酶吸附，在酶级联反应中生产产物的理想功能，高储存稳定性和增强的可回收性。使用SEM对开发的DEMC@L-AI+L-RI进行了表征，FTIR,CLSM和TGA。在微复合材料表面的固定化产率为32％，酶的负载量为22％。DEMC@L-AI+L-RI在pH5-6和温度40°C下表现出相对稳定的催化活性。固定后，两种酶的催化效率（kcat/Km）均提高了1.5倍。有了固定化的生物催化剂，L-阿拉伯糖向L-核糖的生物转化为22.6%,D-半乳糖向D-滑石的生物转化为15.2%。对于超过50%的糖收率,观察到开发的生物催化剂的可重复使用性超过六个循环。甜菜根和洋葱废渣中生物质糖的转化率分别为20％和14％，以产生核糖和牛糖，分别。
