Structural and Functional Features of Ketose-3-Epimerases and Their Use for D-Allulose Production

Abstract Rare sugars attract more and more attention as safe low-calorie sweeteners and functional compounds in the food, pharmaceutical and medical industries. D-Allulose, first discovered in wheat over 70 years ago, has significant application potential but its widespread use is limited by high production costs. The epimerization reactions of available sugars resulting in D-allulose production are catalyzed by enzymes of the epimerase group, ketose-3-epimerases. The key tasks of the study of the ketose-3-epimerases family enzymes are defining the exact mechanisms of their action, the improvement of enzymatic activity and stability in order to achieve a higher efficiency of D-allulose production. The review summarizes the latest innovations in the use of ketose-3-epimerases and optimization of D-allulose manufacturing processes. The structural features of the main enzymes explored in the production of the rare sugar, molecular modifications of biocatalysts, and prospects for the practical use of discussed in this work enzyme pathways are also considered.