Optimization of immobilization conditions of Mucor miehei lipase onto Florisil via polysuccinimide spacer arm using response surface methodology and application of immobilized lipase in asymmetric acylation of 2-amino-1-phenylethanols

Abstract

In this study, the immobilization of Mucor miehei lipase onto Florisil® support via polysuccinimide spacer arm was scrutinized by using a 3-factor and 3-level Box–Behnken design. The independent parameters were immobilization pH, immobilization time and initial lipase concentration and the response was the specific activity of immobilized lipase. A quadratic equation was used to explain the relationship between the response and independent parameters. After analysis of variance test, coefficient of determination and adjusted coefficient of determination values were estimated as 0.98 and 0.94, respectively. The optimal immobilization pH, immobilization time and initial lipase concentration were determined as 6.0, 7 h and 1.1 mg mL−1, respectively, after desirability analysis. The specific activity values for three individual experiments were observed as 25.88 ± 0.73, 26.06 ± 0.47 and 25.96 ± 0.52 U mg protein−1 under the optimized conditions. The hydrolytic activities of free and immobilized lipase preparations were characterized using p-nitrophenyl palmitate as substrate. The esterification activity of immobilized lipase preparation was evaluated by asymmetric acylation of 2-(methylamino)-1-phenylethanol, 2-(ethylamino)-1-phenylethanol, 2-(butylamino)-1-phenylethanol, and 2-(hexylamino)-1-phenylethanol with vinyl acetate. The acylation protocol was optimized in terms of the effects of initial water amount, reaction temperature, molar ratio of amino alcohol to vinyl acetate, biocatalyst loading, organic medium and kind of lipases used. The developed protocol provided a facile methodology for the preparation of enantiopure 2-amino-1-phenylethanols which may be used as potential new β-adrenergic receptor antagonists.