Abstract

The recombinant rPichia/lip lipase was immobilized by adsorbing the enzyme on aggregated carbon nanotubes (CNTs), unmodified, or doped with nitrogen (N-CNTs). Heterogeneous biocatalysts prepared in this way were investigated in the reaction of the low-temperature synthesis of esters proceeding in organic solvents at room temperature. We studied the effect of the texture and morphology of the CNTs, as well as the nitrogen concentration in doped N-CNTs, on the catalytic properties of immobilized lipase, such as activity, specificity, and stability. The activity of biocatalysts and the specific activity of the adsorbed enzyme increased by 1.5–1.6 times with an increase in the concentration of nitrogen introduced into the CNTs (2 and 5 wt % of nitrogen). When studying the specificity of the esterification of saturated fatty acids (heptanoic, stearic) with aliphatic alcohols (n-butanol, n-hexadecanol), the maximum rate was observed in the synthesis of n-butyl heptanoate. The prepared biocatalysts were highly stable in the batch process of the low-temperature synthesis of esters, while retaining at least 80–85% of the activity of the conditioned biocatalysts for 36 reaction cycles (720 h).

中文翻译：

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碳纳米管上r Pichia / liplipase酯在低温合成酯中的催化性能

摘要

重组毕赤酵母通过将酶吸附在未修饰的或掺杂有氮（N-CNT）的聚集碳纳米管（CNT）上，将脂肪酶固定化。在室温下在有机溶剂中进行的酯的低温合成反应中，研究了以此方式制备的多相生物催化剂。我们研究了碳纳米管的质地和形态以及掺杂的N-碳纳米管中的氮浓度对固定化脂肪酶催化性能（例如活性，特异性和稳定性）的影响。随着引入碳纳米管的氮浓度（氮的2和5 wt％）的增加，生物催化剂的活性和吸附的酶的比活性提高了1.5-1.6倍。在研究饱和脂肪酸（庚酸，正丁醇，正十六醇），在庚酸正丁酯的合成中观察到最大速率。所制备的生物催化剂在酯的低温合成的间歇过程中高度稳定，同时在36个反应周期（720小时）中保留了条件生物催化剂的至少80-85％的活性。