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

Area of Science:

• Biocatalysis
• Chemical Engineering
• Organic Chemistry

Background:

• Chirality is crucial in pharmaceutical development.
• Multi-enzyme cascade catalysis provides high stereoselectivity for chiral molecule synthesis.
• Biocatalytic synthesis offers a sustainable route to complex molecules.

Purpose of the Study:

• To engineer a continuous-flow modular reactor for the stereoselective synthesis of norepinephrine.
• To enhance the stereoselectivity of L-threonine aldolase (L-TA) using a chiral microenvironment.
• To optimize norepinephrine yield through a modular reactor design.

Main Methods:

• Development of a continuous-flow modular reactor with two functional modules: a chiral catalytic reactor and a decarboxylation reactor.
• Modification of the microenvironment surrounding L-TA to improve Cβ stereoselectivity.
• Utilizing molecular dynamics simulations to understand active site conformational changes.
• Optimization of the column height ratio between the chiral and decarboxylation modules.

Main Results:

• Significant enhancement in L-TA stereoselectivity, with a 4.1-fold increase in de value (from 18.4% to 75.01%) due to microenvironment modification.
• Molecular dynamics simulations revealed that microenvironment changes altered the enzyme's active site conformation.
• Optimal column height ratio (3:5) achieved a norepinephrine yield of 3.07 g/L.
• Demonstrated successful stereoselective synthesis of norepinephrine.

Conclusions:

• A tailored chiral microenvironment within a modular reactor significantly enhances biocatalytic stereoselectivity.
• The developed reactor strategy is effective for the continuous-flow synthesis of pharmaceutical intermediates like norepinephrine.
• This approach holds promise for efficient and stereoselective production of chiral drugs.