[Enzymatic production of 1,4-cyclohexanedimethylamine]

1,4-cyclohexanedimethylamine (1,4-BAC) is an important monomer for bio-based materials, it finds wide applications in various fields including organic synthesis, medicine, chemical industry, and materials. At present, its synthesis primarily relies on chemical method, which suffer from issues such as expensive metal catalyst, harsh reaction conditions, and safety risks. Therefore, it is necessary to explore greener alternatives for its synthesis. In this study, a two-bacterium three-enzyme cascade conversion pathway was successfully developed to convert 1,4-cyclohexanedicarboxaldehyde to 1,4-cyclohexanedimethylamine. This pathway used Escherichia coli derived aminotransferase (EcTA), Saccharomyces cerevisiae derived glutamate dehydrogenase (ScGlu-DH), and Candida boidinii derived formate dehydrogenase (CbFDH). Through structure-guided protein engineering, a beneficial mutant, EcTA^F91Y, was obtained, exhibiting a 2.2-fold increase in specific activity and a 1.9-fold increase in k_cat/K_m compared to that of the wild type. By constructing recombinant strains and optimizing reaction conditions, it was found that under the optimal conditions, a substrate concentration of 40 g/L could produce (27.4±0.9) g/L of the product, corresponding to a molar conversion rate of 67.5%±2.1%.