skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Friday, September 13 until 2:00 AM ET on Saturday, September 14 due to maintenance. We apologize for the inconvenience.


Title: Engineering Enzyme Substrate Scope Complementarity for Promiscuous Cascade Synthesis of 1,2‐Amino Alcohols
Abstract

Biocatalytic cascades are uniquely powerful for the efficient, asymmetric synthesis of bioactive compounds. However, high substrate specificity can hinder the scope of biocatalytic cascades because the constituent enzymes may have non‐complementary activity. In this study, we implemented a substrate multiplexed screening (SUMS) based directed evolution approach to improve the substrate scope overlap between a transaldolase (ObiH) and a decarboxylase for the production of chiral 1,2‐amino alcohols. To generate a promiscuous cascade, we engineered a tryptophan decarboxylase to act efficiently on β‐OH amino acids while avoiding activity onl‐threonine, which is needed for ObiH activity. We leveraged this exquisite selectivity with matched substrate scope to produce a variety of enantiopure 1,2‐amino alcohols in a one‐pot cascade from aldehydes or styrene oxides. This demonstration shows how SUMS can be used to guide the development of promiscuous, C−C bond forming cascades.

 
more » « less
NSF-PAR ID:
10379125
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie
Volume:
134
Issue:
46
ISSN:
0044-8249
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Biocatalytic cascades are uniquely powerful for the efficient, asymmetric synthesis of bioactive compounds. However, high substrate specificity can hinder the scope of biocatalytic cascades because the constituent enzymes may have non‐complementary activity. In this study, we implemented a substrate multiplexed screening (SUMS) based directed evolution approach to improve the substrate scope overlap between a transaldolase (ObiH) and a decarboxylase for the production of chiral 1,2‐amino alcohols. To generate a promiscuous cascade, we engineered a tryptophan decarboxylase to act efficiently on β‐OH amino acids while avoiding activity onl‐threonine, which is needed for ObiH activity. We leveraged this exquisite selectivity with matched substrate scope to produce a variety of enantiopure 1,2‐amino alcohols in a one‐pot cascade from aldehydes or styrene oxides. This demonstration shows how SUMS can be used to guide the development of promiscuous, C−C bond forming cascades.

     
    more » « less
  2. Abstract

    Enzymes from secondary metabolic pathways possess broad potential for the selective synthesis of complex bioactive molecules. However, the practical application of these enzymes for organic synthesis is dependent on the development of efficient, economical, operationally simple, and well‐characterized systems for preparative scale reactions. We sought to bridge this knowledge gap for the selective biocatalytic synthesis of β‐hydroxy‐α‐amino acids, which are important synthetic building blocks. To achieve this goal, we demonstrated the ability of ObiH, anl‐threonine transaldolase, to achieve selective milligram‐scale synthesis of a diverse array of non‐standard amino acids (nsAAs) using a scalable whole cell platform. We show how the initial selectivity of the catalyst is high and how the diastereomeric ratio of products decreases at high conversion due to product re‐entry into the catalytic cycle. ObiH‐catalyzed reactions with a variety of aromatic, aliphatic and heterocyclic aldehydes selectively generated a panel of β‐hydroxy‐α‐amino acids possessing broad functional‐group diversity. Furthermore, we demonstrated that ObiH‐generated β‐hydroxy‐α‐amino acids could be modified through additional transformations to access important motifs, such as β‐chloro‐α‐amino acids and substituted α‐keto acids.

     
    more » « less
  3. Abstract

    Biocatalytic processes are highly selective and specific. However, their utility is limited by the comparatively narrow scope of enzyme‐catalysed transformations. To expand product scope, we are developing biocompatible processes that combine biocatalytic reactions with chemo‐catalysis in single‐flask processes. Here, we show that a chemocatalysed Pictet‐Spengler annulation can be interfaced with biocatalysed alcohol oxidation. This two‐step, one‐pot cascade reaction converts tyramine and aliphatic alcohols to tetrahydroisoquinoline alkaloids in aqueous buffer at mild pH. Tryptamine derivatives are also efficiently converted to tryptolines. Optimization of stoichiometry, pH, reaction time, and whole‐cell catalyst deliver the tetrahydroisouinolines and tryptolines in >90 % and >40 % isolated yield, respectively, with excellent regioselectivity.

     
    more » « less
  4. Abstract

    Chiral 1,2‐amino alcohols are widely represented in biologically active compounds from neurotransmitters to antivirals. While many synthetic methods have been developed for accessing amino alcohols, the direct aminohydroxylation of alkenes to unprotected, enantioenriched amino alcohols remains a challenge. Using directed evolution, we have engineered a hemoprotein biocatalyst based on a thermostable cytochromecthat directly transforms alkenes to amino alcohols with high enantioselectivity (up to 2500 TTN and 90 %ee) under anaerobic conditions withO‐pivaloylhydroxylamine as an aminating reagent. The reaction is proposed to proceed via a reactive iron‐nitrogen species generated in the enzyme active site, enabling tuning of the catalyst's activity and selectivity by protein engineering.

     
    more » « less
  5. Abstract

    Chiral 1,2‐amino alcohols are widely represented in biologically active compounds from neurotransmitters to antivirals. While many synthetic methods have been developed for accessing amino alcohols, the direct aminohydroxylation of alkenes to unprotected, enantioenriched amino alcohols remains a challenge. Using directed evolution, we have engineered a hemoprotein biocatalyst based on a thermostable cytochromecthat directly transforms alkenes to amino alcohols with high enantioselectivity (up to 2500 TTN and 90 %ee) under anaerobic conditions withO‐pivaloylhydroxylamine as an aminating reagent. The reaction is proposed to proceed via a reactive iron‐nitrogen species generated in the enzyme active site, enabling tuning of the catalyst's activity and selectivity by protein engineering.

     
    more » « less