Continuous-Flow Modular Reactor with a Chiral Microenvironment Enhances the Biocatalytic Synthesis of Norepinephrine

Chirality lies at the core of pharmaceutical molecular design. Multi-enzyme cascade catalysis offers high stereoselectivity for constructing such molecules. Here, we present a continuous-flow modular reactor engineered with a chiral microenvironment for the biocatalytic synthesis of norepinephrine. This system incorporates two functional modules: a chiral catalytic reactor, designed to enhance the C_β stereoselectivity of L-threonine aldolase (L-TA), and a decarboxylation reactor to balance catalytic rates. Modifying the microenvironment surrounding L-TA significantly enhanced its stereoselectivity, with 4.1 times increased the de value (from 18.4% to 75.01%). Seen from molecular dynamics simulations, these modifications reshaped the spatial conformation of the enzyme's active site. Moreover, at an optimal column height ratio of 3:5 between the chiral and decarboxylation modules, norepinephrine yield reached 3.07 g/L. This modular reactor strategy, enhanced by a tailored chiral microenvironment, offers substantial promise for the stereoselective synthesis of pharmaceutical intermediates.