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Updated: Jul 5, 2025

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products

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Published on: October 4, 2019

Controlling Monoterpene Isomerization by Guiding Challenging Carbocation Rearrangement Reactions in Engineered

Julian Ludwig¹, Christian Curado-Carballada², Stephan C Hammer^1,3

¹Department of Technical Biochemistry, Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany.

Angewandte Chemie (International Ed. in English)

|January 25, 2024

Summary

Engineered enzymes precisely control terpene isomerization, overcoming limitations of traditional catalysts. This breakthrough offers targeted skeletal reorganization for valuable terpene compounds.

Keywords:

Biocatalysis Brønsted Acid Catalysis Secondary Carbocations Sustainable Chemistry Terpenoids

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Area of Science:

Biocatalysis
Organic Chemistry
Enzyme Engineering

Background:

Monoterpene interconversion involves complex carbocation rearrangements.
Conventional acid catalysts lack selectivity, yielding difficult-to-separate product mixtures.
Natural terpene cyclases offer high control but require specific substrates.

Purpose of the Study:

To engineer squalene-hopene cyclases (AacSHC) for precise monoterpene isomerization.
To demonstrate controlled carbocation steering in terpene skeletal reorganization.
To enhance selectivity for specific terpene products.

Main Methods:

Site-directed mutagenesis and iterative saturation mutagenesis of AacSHC.
Analysis of product distribution from (+)-β-pinene isomerization.
Computational modeling to elucidate catalytic mechanisms.

Main Results:

Single point mutations significantly altered product distribution.
Engineered AacSHC achieved >90% selectivity for (+)-borneol (>99% de).
Mutations induced reorganization of aromatic residues and water networks, guiding cation termination.

Conclusions:

Engineered AacSHC provides unprecedented precision in monoterpene isomerization.
Mechanistic insights reveal how enzyme active site restructuring controls carbocation pathways.
This approach enables targeted skeletal reorganization of abundant terpenes.