Enantioselective Hydrolysis of Some 2-Aryloxyalkanoic Acid Methyl Esters and Isosteric Analogues Using a Penicillin G Acylase-Based HPLC Monolithic Silica Column
作者:Gabriella Massolini、Enrica Calleri、Antonio Lavecchia、Fulvio Loiodice、Dieter Lubda、Caterina Temporini、Giuseppe Fracchiolla、Paolo Tortorella、Ettore Novellino、Gabriele Caccialanza
DOI:10.1021/ac0204193
日期:2003.2.1
A technique based on liquid chromatography has been developed to facilitate studies of enantioselectivity in penicillin G acylase (PGA)-catalyzed hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues. PGA was covalently immobilized on an aminopropyl monolithic silica support to create an immobilized HPLC-enzyme reactor. Two sets of experimental data were drawn to calculate the enantioselectivity (E) of the kinetically controlled enantiomer-differentiating reaction, the degree of substrate conversion and the enantiomeric excess of the product. The developed enzymatic reactor was coupled through a switching valve to an achiral analytical column for separation and quantitation of the hydrolysis products. The enantiomeric excess was determined off-line on a PGA-chiral stationary phase. In this way, highly precise E values were determined. A computational study related to the hydrolysis of the considered racemic esters was also carried out in order to unambiguously clarify both the substrate specificity and the enantioselectivity displayed by PGA.
一种基于液相色谱的技术已被开发出来,以便于研究青霉素G酰化酶(PGA)催化某些2-芳氧烷基酸甲酯及其同效物的水解反应中的对映选择性。PGA被共价固定在氨丙基单体硅胶支撑物上,创建了一个固定化HPLC-酶反应器。通过两组实验数据,计算了动力学控制的对映体区分反应的对映选择性(E)、底物转化率以及产物的对映过量。所开发的酶反应器通过切换阀与无手性的分析柱连接,用于分离和定量水解产物。对映过量在线上通过PGA-手性固定相确定。通过这种方式,获得了高度精确的E值。此外,还进行了与所考虑的外消旋酯水解相关的计算研究,以明确PGA所表现出的底物特异性和对映选择性。