A green and sustainable multi-enzyme cascade for 1,3-diaminopropane biosynthesis from crude glycerol in vitro

Abstract

1,3-Propanediamine is a diamine widely used in microelectronics and porous materials. It can also be used as a curing agent for epoxy resin, forming valuable three-dimensional structures, or as a raw material for synthesizing the radiation-resistant drug amifostine. However, traditional chemical synthesis methods for producing 1,3-propanediamine often contradict the 12 principles of green chemistry. In this study, we designed a new pathway for producing 1,3-diaminopropane through a retrosynthetic-designed multi-enzyme cascade from crude glycerol in vitro. Compared with traditional chemical methods, this multienzyme cascade is simpler in process, less energy-consuming, cleaner in substrate usage, and more environmentally friendly. In the cascade reaction, we selected glycerol dehydratase (KpGDHT) to dehydrate the intermediate product 3-amino-1,2-propanediol based on substrate promiscuity. We then modified the substrate preference of KpGDHT to obtain the optimized mutant KpGDHT/Q337A/S302D, which exhibited a 4.4-fold increase in activity toward 3-amino-1,2-propanediol compared with the wild-type KpGDHT. Using KpGDHT/Q337A/S302D as the catalyst, 3.8 mM 1,3-diaminopropane was produced from 5 mM glycerol within 8h under optimal conditions, achieving 76% conversion efficiency. Finally, we evaluated the performance of 1,3-diaminopropane synthesized from crude glycerol and obtained 1,3-diaminopropane with a concentration of 3.95 mM, which is comparable to that from pure glycerol. Given its robustness and environmental benefits, this proposed cascade reaction pathway has great potential to produce 1,3-diaminopropane on an industrial scale.