Faculty of Chemistry

by S. Gergel, J. Soler, A. Klein, K. H. Schülke, B. Hauer, M. Garcia-Borràs and S. Hammer.

The direct regioselective oxidation of internal alkenes to ketones poses an important synthetic challenge. Now, directed evolution of a cytochrome P450 enzyme affords a ketone synthase that can efficiently oxidize internal arylalkenes directly to ketones with high chemo- and regioselectivity.

Nature Catalysis 2023

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

The paper "Prolinyl Nucleotides Drive Enzyme-Free Genetic Copying of RNA" from Prof. Richert was nominated for the cover of Angewandte (vide infra). It shows that long reads of mixed sequence RNA can be achieved with an amino acid as leaving group.

Angew. Chem. Int. Ed.2023, e202307591

For further information please contact:
Prof. Clemens Richert
Institute of Organic Chemistry
University of Stuttgart

by Shubhadeep Chandra, Dr. Arijit Singha Hazari, Dr. Qian Song, David Hunger, Dr. Nicolás I. Neuman, Prof. Dr. Joris van Slageren, Prof. Dr. Elias Klemm, Prof. Dr. Biprajit Sarkar.

For further information please contact:
Prof. Biprajit Sarkar
Institute of Inorganic Chemistry
University of Stuttgart

by Jona T. Schelle, William Lepottevin and Bernhard Hauer

Oxyfunctionalization reactions are of great interest in organic chemistry and industry. Rieske non-heme iron oxygenases, such as cumene dioxygenase, have shown significant potential for these reactions. However, scaling up oxygenase-catalyzed reactions can be challenging due to their reliance on molecular oxygen. In this study, we optimized the reaction set-up and oxygen uptake for cumene dioxygenase-catalyzed biotransformations and successfully scaled up the reaction volume from 1 mL to 200 mL. Our results demonstrate the applicability of our set-up for product isolation and characterization.

Chemie Ingenieur Technik 95,5: 607 – 611 (2023)

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Benjamin Aberle,  Daniel Kowalczyk,  Simon Massini,  Alexander-N. Egler-Kemmerer,  Sebastian Gergel,  Stephan Hammer,  Bernhard Hauer

Terpenes are natural compounds with diverse applications, but the available carbon scaffolds are limited by their biosynthesis from five carbon precursors. To gain access to non-natural terpenoids, we identified and engineered methyltransferases for late-stage C-methylation of unactivated alkenes. The engineering resulted in a 55-fold improvement of conversion of (E,E)-farnesol with > 99% selectivity. In total, five non-natural terpenoids were produced and isolated using this biocatalytic method. This opens new avenues for the modification of the carbon scaffold of terpenes.

Angewandte Chemie int. Ed.

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Andreas Schneider; Christian Curado; Thomas B. Lystbaek; Sílvia Osuna; Bernhard Hauer

Angewandte Chemie: DOI number​ 10.1002/anie.202301607

The synthetic power of terpene cyclases is of broad academic as well as industrial interest as it can cut down synthetic routes to complex cyclic terpenes to essentially one step. However, these enzymes usually lack catalytic turnovers and stability under the new-to-nature conditions. Teaming up with the BioCompLab, Girona of Silvia Osuna, we showcase the synergy of tailoring the active site and entrance tunnel of the squalene-hopene cyclase for the stereocontrolled cationic cyclization of E,E-homofarnesol to (–)-ambroxide with >100.000 total turnovers.

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Kristina Schell, Heng Li, Lukas Lauterbach, Kizerbo A. Taizoumbe, Jeroen S. Dickschat and Bernhard Hauer 

Enzyme active site confinement is important for efficient chemical reactions and catalysis. However, a strongly confined active site limits the range of substrates that can be used. In this study we developed a structure-guided strategy to create alternative confinement in the squalene-hopene cyclase enzyme, which aims to pre-organize geranyl acetone analogs with deviant isoprene patterns via proximity and substrate shape complementarity. The approach generated a final enzyme variant with significantly increased turnover number and catalytic efficiency, demonstrating potential to overcome limitations in biocatalyst engineering and generate interesting building blocks.

ACS Catalysis 2023, 13, 5073-5083

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Dongyang Chen, Francisco Tenopala-Carmona, Julius A. Knöller, Andreas Mischok, David Hall, Subeesh Madayanad Suresh, Tomas Matulaitis, Yoann Olivier, Pierre Nacke, Frank Gießelmann, Sabine Laschat, Malte C. Gather, Eli Zysman-Colman

The use of thermally activated delayed fluorescence (TADF) emitters and emitters that show preferential horizontal orientation of their transition dipole moment (TDM) are two emerging strategies to enhance the efficiency of OLEDs. We present the first example of a liquid crystalline multi-resonance TADF (MR-TADF) emitter, DiKTa-LC. The compound possesses a nematic liquid crystalline phase between 80 °C and 110 °C. Importantly, the TDM of the spin-coated film shows preferential horizontal orientation, with an anisotropy factor, a, of 0.28, which is preserved in doped poly(vinylcarbazole) films.  Green-emitting (λEL = 492 nm) solution-processed OLEDs based on DiKTa-LC showed an EQEmax of 13.6%. We thus demonstrate for the first time how self-assembly of a liquid crystalline TADF emitter can lead to the so-far elusive control of the orientation of the transition dipole in solution-processed films, which will be of relevance for high-performance solution-processed OLEDs.

Angew. Chem. Int. Ed. 2023, e202218911.

For further information please contact
Prof. Sabine Laschat
Institute of Organic Chemistry
University of Stuttgart

by Andreas Schneider, Jacqueline Ruppert, Thomas B. Lystbaek, Silke Bastian, Bernhard Hauer.

ACS Catal. 2023, 13, XXX, 1946–1951

Nature evolved the active site of the squalene-hopene cyclase (SHC) for perfectly aligned shape-complementary interactions with its substrate squalene. The resulting strong confinement is a prerequisite to guide the carbocationic intermediates of the Brønsted-acid catalyzed polycyclizations of terpenes. In contrast, however, this confined active site restricts the activation of deviant substrates. Writing in ACS Catalysis, we describe how to tailor the active site of the SHC for a highly enantioselective semipinacol rearrangement of bicyclic allylic alcohols. This work further highlights the general applicability of the SHC for stereoselective Brønsted acid catalysis.

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Simon Suhr, Robert Walter, Julia Beerhues, Uta Albold and Biprajit Sarkar

Chem. Sci., 2022, 13, 10532

For further information please contact:
Prof. Biprajit Sarkar
Institute of Inorganic Chemistry
University of Stuttgart

by Ana I. Benítez-Mateos, Andreas Schneider, Eimear Hegartry, Bernhard Hauer and Francesca Paradisi

Nature Communication: 10.1038/s41467-022-34030-0

Terpene cyclases are of great chemical interest due to their unique ability to forge chiral cyclic hydrocarbon scaffolds within a single cationic cyclization cascade. In our newest collaboration with the Paradisi Lab, Univ. Bern we describe a new method to boost the catalytic performance of the membrane-bound squalene-hopene cyclase. Using the enzyme in a spheroplast environment, we could overcome the diffusion barrier of the E. coli outer membrane and thus improve the catalytic cyclization of a broad substrate scope by up to 100-fold. 

For further information please contact:
Prof. Bernhard Hauer
Institute of Biochemistry and Technical Biochemistry,
Department Technical Biochemistry
University of Stuttgart

by Gabrielle Leveau, Daniel Pfeffer, Bernhard Altaner, Eric Kervio, Franziska Welsch, Ulrich Gerland and Clemens Richert

When dinucleotides were allowed to act as building blocks for enzyme-free genetic copying of RNA, sequences up to 12 bases in length were faithfully transmitted into the copy.

Angew. Chem. 2022, e202203067

For further information please contact:
Prof. Clemens Richert
Institute of Organic Chemistry
University of Stuttgart