Stabilization of D-Amino Acid Oxidase via Covalent Immobilization and Mathematical Model of D-Methionine Oxidative Deamination Catalyzed by Immobilized Enzyme

Z. Findrik Blažević, M. Tusić and Đ. Vasić-Rački

Abstract
Porcine kidney D-amino acid oxidase was stabilized by covalent immobilization on spherical particles of Eupergit C because of its low stability in soluble form. The focus of this work was to evaluate operational stability of the immobilized enzyme. To evaluate D-amino acid oxidase’s operational stability during process conditions, repetitive batch reactor experiments of D-methionine oxidation reaction were carried out with continuous aeration for oxygen supply at air-flow rates of 5 and 10 dm3 h–1. Kinetic analysis of the immobilized enzyme was done as well. The mathematical model of D-methionine oxidative deamination catalyzed by the immobilized D-amino acid oxidase was developed and it described the data well. It enabled the estimation of operational stability decay rate constant. It was possible to achieve 100 % substrate conversion in all batch experiments.

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Keywords
amino acid oxidase, enzyme immobilization, enzyme kinetics, mathematical model