Patel Vrutika, Shah Chandani, Deshpande Milind, Madamwar Datta
Environmental Genomics and Proteomics Lab, BRD School of Biosciences, Sardar Patel Maidan, Satellite campus, Sardar Patel University, Sardar Patel Maidan, P.O. Box # 39, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India.
Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India.
Appl Biochem Biotechnol. 2016 Apr;178(8):1630-51. doi: 10.1007/s12010-015-1972-9. Epub 2016 Jan 9.
The present study describes grafting of zinc oxide (ZnO) nanoparticles with polyethyleneimine (PEI) followed by modification with glutraldehyde used as the bridge for binding the enzyme to support. The prepared nanocomposites were then characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy, utilized for synthesis of geranyl acetate in n-hexane. Among all the three prepared nanocomposites (ZnO + PEI, ZnO + PEI + SAA, ZnO + PEI + GLU), Candida rugosa lipase immobilized on ZnO-PEI-GLU was found to be best for higher ester synthesis. The operating conditions that maximized geranyl acetate resulted in the highest yield of 94 % in 6 h, molar ratio of 0.1:0.4 M (geraniol/vinyl acetate) in the presence of n-hexane as reaction medium. Various kinetic parameters such as V max, K i(G), K m(G), and K m(VA) were determined using nonlinear regression analysis for order bi-bi mechanism. The kinetic study showed that reaction followed order bi-bi mechanism with inhibition by geraniol. Activation energy (E a ) was found to be lower for immobilized lipase (12.31 kJ mol(-1)) than crude lipase (19.04 kJ mol(-1)) indicating better catalytic efficiency of immobilized lipase. Immobilized biocatalyst demonstrated 2.23-fold increased catalytic activity than crude lipase and recycled 20 times. The studies revealed in this work showed a promising perspective of using low-cost nanobiocatalysts to overcome the well-known drawbacks of the chemical-catalyzed route.
本研究描述了用聚乙烯亚胺（PEI）接枝氧化锌（ZnO）纳米颗粒，然后用戊二醛进行改性，戊二醛用作将酶与载体结合的桥梁。然后使用傅里叶变换红外光谱、热重分析和透射电子显微镜对制备的纳米复合材料进行表征，并将其用于在正己烷中合成乙酸香叶酯。在制备的三种纳米复合材料（ZnO + PEI、ZnO + PEI + SAA、ZnO + PEI + GLU）中，固定在ZnO-PEI-GLU上的皱褶假丝酵母脂肪酶被发现最适合用于更高的酯合成。使乙酸香叶酯产量最大化的操作条件在6小时内产生了94%的最高产率，在正己烷作为反应介质存在的情况下，香叶醇/乙酸乙烯酯的摩尔比为0.1:0.4 M。使用非线性回归分析确定了各种动力学参数，如V max、K i(G)、K m(G)和K m(VA)，用于双底物双分子机制。动力学研究表明，反应遵循双底物双分子机制，香叶醇有抑制作用。发现固定化脂肪酶的活化能（E a）（12.31 kJ mol(-1)）低于粗脂肪酶（19.04 kJ mol(-1)），这表明固定化脂肪酶具有更好的催化效率。固定化生物催化剂的催化活性比粗脂肪酶提高了2.23倍，并且可以循环使用20次。这项工作中的研究表明，使用低成本的纳米生物催化剂来克服化学催化路线的众所周知的缺点具有广阔的前景。
