Engineered biocatalyst and its desired products using nanotechnology has intensified the research in food industries. Zinc oxide (ZnO) nanosheet is designed and prepared; the characterization studies include surface plasmon resonance peak (364 nm), X-ray diffraction pattern determined crystallite size (25 nm), and transmission electron microscopy confirms the porous surface nature. Atomic force microscopy showed substrate and enzyme adsorbed on ZnO nanosheets. The zeta potential of ZnO nanosheet (−41.9 mV) whereas α-amylase bound with ZnO nanosheets (−32.8 mV), and starch bound with ZnO nanosheets (−28.7 mV) was analyzed using dynamic light scattering. The circular dichroism spectra displayed α-helix in native amylase at optimum concentration 54.70% compared to the adsorbed α-amylase with ZnO nanosheet that showed 37%. Freundlich isotherm model revealed multilayer adsorption behavior of α-amylase onto porous ZnO nanosheet. Enzyme kinetics study presents alteration in Michaelis–Menten constant (Km) and maximum velocity (Vmax), the α-amylase bound with porous ZnO nanosheet showed a reduction in Km and Vmax. The substrate and enzyme adsorbed together on porous ZnO nanosheet exhibited increased Km (27.77 μM), whereas Vmax (2.85 μM) remains unchanged. Moreover, α-amylase once modified at optimum pH (5.8) and temperature (52 °C), produces less maltose than α-amylase adsorbed on ZnO nanosheet, which indicates higher maltose production. In this study, ZnO nanosheet enzyme catalytic system was created, wherein enzymatic reaction shifted to different pH and temperature other than optimum conditions. All these findings suggest that careful attention to the enzyme adsorption profiles can contribute to industrial applications.

Graphical abstract

中文翻译：

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多孔氧化锌纳米片吸附α-淀粉酶和淀粉的生物物理研究

使用纳米技术的工程生物催化剂及其所需的产品加强了食品工业的研究。设计并制备了氧化锌（ZnO）纳米片；表征研究包括表面等离振子共振峰（364 nm），X射线衍射图确定的微晶尺寸（25 nm），以及透射电子显微镜确定的多孔表面性质。原子力显微镜显示基质和酶吸附在ZnO纳米片上。使用动态光散射分析了ZnO纳米片（-41.9 mV）的zeta电位，而与ZnO纳米片（-32.8 mV）结合的α-淀粉酶和与ZnO纳米片（-28.7 mV）结合的淀粉。圆二色性光谱显示天然淀粉酶中α-螺旋的最佳浓度为54.70％，而吸附有ZnO纳米片的α-淀粉酶则为37％。Freundlich等温线模型揭示了α-淀粉酶在多孔ZnO纳米片上的多层吸附行为。酶动力学研究表明，Michaelis-Menten常数（Km）和最大速度（Vmax）发生了变化，与多孔ZnO纳米片结合的α-淀粉酶显示Km和Vmax降低。吸附在多孔ZnO纳米片上的底物和酶一起显示出增加的Km（27.77μM），而Vmax（2.85μM）保持不变。此外，α-淀粉酶一旦在最佳pH（5.8）和温度（52°C）下进行修饰，所产生的麦芽糖比吸附在ZnO纳米片上的α-淀粉酶要少，这表明麦芽糖的产量更高。在这项研究中，创建了ZnO纳米片酶催化系统，其中酶促反应转移到了除最佳条件以外的不同pH和温度。

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