Effect of Immobilization on the Stability and Specificity of Choline Oxidase

Choline oxidase catalyzes the conversion of choline into glycine betaine and hydrogen peroxide. Choline oxidase has two roles in industry and medicine, as a sensor of choline, and in the synthesis of glycine betaine. For optimal utility in industrial synthesis pathways, choline oxidase must have a broad specificity while maintaining activity over a range of pH and temperature. The specificity, pH optimum, temperature stability, of choline oxidase from three different sources was determined. In order to address low stability at elevated temperatures, choline oxidase was immobilized on CNBr‐activated Sepharose beads. Immobilized choline oxidase showed enhanced stability over a broader range of temperature and pH. Preliminary data suggests that immobilized choline oxidase has reduced specificity for choline and other quaternary ammonium salts. New methods for testing specificity to confirm this preliminary data are under investigation.