Biosynthesis of Furfurylamines in Batch and Continuous Flow by Immobilized Amine Transaminases

Building blocks with amine functionality are crucial in the chemical industry. Biocatalytic syntheses and chemicals derived from renewable resources are increasingly desired to achieve sustainable production of these amines. As a result, renewable materials such as furfurals, especially furfurylamines like 5-(hydroxymethyl)furfurylamine (HMFA) and 2,5-di(aminomethyl)furan (DAF), are gaining increasing attention. In this study, we identified four different amine transaminases (ATAs) that catalyze the reductive amination of 5-(hydroxymethyl)furfural (HMF) and 2,5-diformylfuran (DFF). We successfully immobilized these ATAs on glutaraldehyde-functionalized amine beads using multiple binding and on amine beads by site-selective binding of the unique Ca-formylglycine within an aldehyde tag. All immobilized ATAs were efficiently reused in five repetitive cycles of reductive amination of HMF with alanine as co-substrate, while the ATA from Silicibacter pomeroyi (ATA-Spo) also exhibited high stability for reuse when isopropylamine was used as an amine donor. Additionally, immobilized ATA-Spo yielded high conversion in the batch syntheses of HMFA and DAF using alanine (87% and 87%, respectively) or isopropylamine (99% and 98%, respectively) as amine donors. We further demonstrated that ATA-Spo was effective for the reductive amination of HMF with alanine or isopropylamine in continuous-flow catalysis with high conversion up to 12 days (48% and 41%, respectively).

Automated summary

In this study, four different amine transaminases (ATAs) were identified to catalyze the reductive amination of 5-(hydroxymethyl)furfural (HMF) and 2,5-diformylfuran (DFF). These ATAs were successfully immobilized on glutaraldehyde-functionalized amine beads and on amine beads by site-selective binding. Immobilized ATAs showed efficient reuse in the reductive amination of HMF with alanine as co-substrate, and the ATA-Spo exhibited high stability for reuse when isopropylamine was used as an amine donor. Additionally, immobilized ATA-Spo achieved high conversion in batch syntheses and continuous-flow catalysis using alanine or isopropylamine as amine donors.