Background. Enzyme immobilization on a support can bring benefits not only due to cost reduction through reuse or ensuring process continuity, but also by changing the specificity of the catalyst for products. A major challenge in enzymatic reactions is the variability of the specificity of the amount of products, which makes the widespread use of enzymatic reactions difficult, increases the costs of product separation and purification. A directed change of enzymes, for example by immobilization, has become a valuable approach to generating enzymes tailored to customer needs.
Results and conclusions. This paper presents studies on the immobilization of cyclodextrin glucosyltransferase (CGTase) EC 2.4.1.19 on dialdehyde starch (DAS), obtained by oxidation of potato starch. Due to the high content of aldehyde groups, CGTase was catalytically inactive towards dialdehyde starch. The CGTase-DAS biocatalyst obtained as a result of immobilization was active in six reaction cycles of obtaining cyclodextrins from potato starch. Higher efficiency than in homogeneous catalysis was obtained in four reaction cycles catalyzed by immobilized CGTase. The biocatalyst was still active in the subsequent cycles, but the reaction proceeded with lower efficiency compared to the reaction with the enzyme in the free state. A change in the ratio of obtained α:β:γ cyclodextrins was observed. The most β-CD was obtained in the reaction with the non-immobilized enzyme. More α-CD was obtained in the reaction with the heterogeneous catalyst in cycles I-III, in subsequent cycles the efficiency of γ-CD was higher than βCD. Due to the multiple use of the heterogeneous biocatalyst, the total amount of obtained cyclodextrins was significantly increased. The presented CGTase-DAS biocatalyst can be successfully used in technological processes to reduce the costs of obtaining cyclodextrins.