Coupled enzymatic reactions for simultaneous synthesis of 1, 3-dihydroxyacetone and 2-aminobutyric acid with in situ regeneration of coenzyme

Simultaneous synthesis of 1, 3-dihydroxyacetone (DHA) and 2-aminobutyric acid from glycerol and 2-oxobutyric acid was achieved by coupling the reactions of two enzymes, glycerol dehydrogenase and leucine dehydrogenase with in situ regeneration of coenzyme. The effects of concentrations of substrates and coenzyme NAD⁺ on the yields of the products and the total turnover number (TTN) of the multi-enzyme reaction system were examined. The results show that the TTN value could reach 5110 with an initial NAD⁺ concentration of 0.1 μmol/L. The observed yields of products were 1.4% and 2.6% for glycerol and 2-oxobutyric acid respectively, based on the amount of substrates used. The strong inhibitory effects of DHA and 2-aminobutyric acid on GDH and LDH were regarded as the main causes for such low product yields. Accordingly, an effective removal strategy of products will be necessary for future improvement of the efficiency of the reaction system.