Characterizing the properties and evaluating the efficiency of biocatalysts based on immobilized fungal amylase

Abstract

Preparations based on native enzymes have limited industrial use because of their instability and sensitivity to the changes in pH, temperature, and other external factors. It is therefore essential to create biocatalysts based on immobilized enzymes that are more stable and thus more efficient in practical application. To stabilize fungal amylase (EC 3.2.1.1.), the enzyme is covalently immobilized on a chitosan-containing cellulose. It is shown that the thermal stability of the immobilized amylase is increased by 350%, compared to the native enzyme, and its resistance to pH-inactivation is also improved. The reduction of the inactivation rate constant and the increase of the Gibbs free energy for the immobilized enzyme, relative to the native enzyme, testify to its increased stability resulting from steric factors associated with the formation of azomethine bonds with cellulose and chitosan. It is shown that using the immobilized enzyme preparation instead of the native amylase increases the product yield in barley malt hydrolysis by a factor of 1.5, allowing us to use this preparation in the food industry.