Biopharmaceutical Technology Institute, Department of Chemical Engineering, Lehigh University, Bethelehem, Pennsylvania 18015, USA.
Biotechnol Bioeng. 1997 Jul 20;55(2):399-407. doi: 10.1002/(SICI)1097-0290(19970720)55:2<399::AID-BIT17>3.0.CO;2-C.
Lipase from Pseudomonas cepacia was used for asymmetric hydrolysis of the substrate (+/-)1-chloro-2-acetoxy-3-(1-naphthyloxy)-propane, which is a precursor for (S)-(-)-beta-blocker synthesis. Because this substrate is insoluble in water and partially soluble in hydrophobic solvents such as hexane and octane, a mixture of hydrophilic organic solvents and aqueous buffer was used to study the initial reaction rates. Because of the amphipathic nature of the substrate, it can remain in three different forms: (1) monomeric (solution); (2) micellar; and (3) emulsion, depending on the acetone and substrate concentrations in the medium. This behavior is presented in a phase diagram. The enzyme was found to be active with micelle as well as emulsion form of the substrate, whereas it showed negligible activity with the monomeric form. Michaelis-Menten constants were determined experimentally for the emulsion and micellar part of the substrate. The initial rate of hydrolysis (v(0)) goes through a maximum with respect to the acetone content of the mixture. It is due to the combined effect of various factors occurring simultaneously with the increase in acetone content in the solvent. These phenomena are discussed based on the interfacial activation of lipase, deactivation of the enzyme at very high acetone concentration, and increase in critical micelle concentration (CMC) and critical emulsion concentration (CEC) with the increase in acetone content in the solvent. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 399-407, 1997.
假单胞菌脂肪酶被用于（±）1-氯-2-乙酰氧基-3-（1-萘氧基）-丙烷的不对称水解，该底物是（S）-（-）β-受体阻滞剂合成的前体。由于该底物不溶于水且部分溶于己烷和辛烷等疏水性溶剂，因此使用亲水性有机溶剂和水性缓冲液的混合物来研究初始反应速率。由于底物的两亲性质，它可以保持三种不同的形式：（1）单体（溶液）；（2）胶束；和（3）乳液，这取决于介质中的丙酮和底物浓度。这种行为以相图的形式呈现。发现该酶对胶束和乳液形式的底物均具有活性，而对单体形式的底物几乎没有活性。实验确定了底物的胶束和乳液部分的米氏常数。水解的初始速率（v（0））相对于混合物中的丙酮含量呈现出最大值。这是由于随着溶剂中丙酮含量的增加，同时发生的各种因素的综合影响。这些现象是基于脂肪酶的界面活化、酶在非常高的丙酮浓度下失活以及临界胶束浓度（CMC）和临界乳液浓度（CEC）随着溶剂中丙酮含量的增加而增加来讨论的。（c）1997 年 John Wiley & Sons，Inc.《生物工艺学与生物工程》55:399-407，1997 年。
