Abstract

A study is performed of the processes of low-temperature enzymatic synthesis of esters in nonaqueous media of organic solvents with the participation of heterogeneous biocatalysts produced by the adsorptive immobilization of recombinant Thermomyces lanuginosus lipase (produced by Pichia pastoris) on macroporous carbon aerogel. Esterification is conducted in individual organic solvents of different polarities, namely nonpolar (lоg P > 2.5) solvents hexadecane, hexane, and toluene; the polar (lоg P < 1) diethyl ether, tert-butanol, and acetone; binary mixtures with different compositions (e.g., hexane with diethyl ether in volume ratio 1 : (1/5–3)). Comparative studies are made of the effect the nature of the solvent and co-solvent on the properties of the prepared biocatalysts (such as enzymatic activity and operational stability) in the batch esterification of heptanoic acid (C7:0) with alcohols such as polar ethanol and n‑butanol, and nonpolar n-octanol and n-hexadecanol. The activity of the biocatalysts is found to depend largely on the polarity of both the solvents used in the reaction and the alcohol substrates. The maximum activity (400 U g⁻¹; 1 U (unit of activity) = 1 μmol min⁻¹) is observed in a medium of nonpolar and inviscid hexane (lоg P = 2.9), while the minimum activity (4 U g⁻¹) is detected in acetone (lоg P = 0.4). There is virtually no esterification of heptanoic acid in the presence of tert-butanol (lоg P = 0.6). The activity of the biocatalysts is found to depend nonmonotonically on the lоg P of individual solvent. In binary mixtures of such organic solvents as hexane and diethyl ether, the biocatalytic activity increases linearly as lоg P_mix increases. The biocatalysts have the maximum operational stability in binary mixture of hexane and diethyl ether.

中文翻译：

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酯低温合成的非均相生物催化过程：选择有机溶剂

摘要

进行了在有机溶剂的非水介质中低温酶促合成酯的过程的研究，该过程是通过将重组嗜热单胞菌lanuginosus脂肪酶（巴斯德毕赤酵母（Pichia pastoris）生产）吸附固定在大孔碳气凝胶上而产生的异质生物催化剂的参与。酯化反应在极性不同的有机溶剂中进行，即非极性（lg  P > 2.5）溶剂十六烷，己烷和甲苯；极性（l P g  <1）乙醚，叔-丁醇和丙酮；具有不同组成的二元混合物（例如，己烷与乙醚的体积比为1：（1 / 5–3））。比较了溶剂和助溶剂的性质对庚酸（C7：0）与醇（如极性乙醇）分批酯化反应中制备的生物催化剂的性能（如酶活性和操作稳定性）的影响。和ñ丁醇和非极性ñ辛醇和ñ -hexadecanol。发现生物催化剂的活性主要取决于反应中使用的溶剂和醇底物的极性。最大活性（400 U g ^-1 ; 1 U（活性单位）= 1μmolmin ^-1）在非极性和无粘性己烷（lg P = 2.9）的介质中观察到 ，而在丙酮（lg g P  = 0.4）中检测到 最小活性（4 U g ^-1）。在叔丁醇存在下，庚酸几乎没有被酯化（l  P = 0.6）。生物催化剂的活性被发现在lоgnonmonotonically取决于 P个别溶剂。在诸如己烷和乙醚之类的有机溶剂的二元混合物中，生物催化活性随磷_混合物的增加而线性 增加。该生物催化剂在己烷和乙醚的二元混合物中具有最大的操作稳定性。