Enantioselective Biocascade Catalysis with a Single Multifunctional Enzyme.

Area of Science:

• Biocatalysis and Organic Synthesis
• Enzyme Engineering
• Asymmetric Catalysis

Background:

• Asymmetric catalytic cascade reactions provide efficient routes to complex chiral molecules.
• Traditional biocatalytic cascades typically involve multiple enzymes, each catalyzing a specific reaction step.
• A need exists for streamlined biocatalytic approaches using fewer components.

Purpose of the Study:

• To develop a novel biocatalytic cascade strategy using a single multifunctional enzyme.
• To engineer an enzyme capable of sequential substrate activation via distinct catalytic mechanisms.
• To synthesize enantiopure cyclohexene carbaldehydes using this engineered enzyme.

Main Methods:

• Engineering of 4-oxalocrotonate tautomerase (4-OT) to possess dual catalytic capabilities (enamine and iminium ion formation).
• Utilizing the engineered 4-OT to catalyze sequential, stereoselective steps in a domino process.
• Activating aldehydes and enals as substrates for cascade reactions.

Main Results:

• Demonstrated a single enzyme, engineered 4-OT, can orchestrate multiple catalytic steps in a cascade.
• Successfully synthesized enantiopure cyclohexene carbaldehydes.
• The enzyme facilitated both a two-component reaction and a triple cascade, showcasing versatility in mechanism and activation sequence.

Conclusions:

• A single multifunctional enzyme can effectively replace multiple enzymes in biocatalytic cascades.
• This strategy offers a powerful approach for the streamlined synthesis of complex chiral molecules.
• Engineered 4-OT provides a versatile platform for developing novel asymmetric catalytic domino processes.