Enzymes are a promising alternative to traditional catalysts. However, their application is more complex than it seems. This chapter explores the complexit

Methylation going sour: The first uncoupled fluorescence-based assay was established to measure methyltransferase activity in a continuous fashion. Different use cases are presented, including the as...

The N-methyltransferase SgPsmC was characterised and applied in the kinetic resolution (KR) of easily obtainable pyrroloindolines. Substitution at 3a-position proved to be a principal determinant for....

The pyrroloindole (hexahydropyrrolo[2,3-b]indole, HPI) structural motif is present in a wide range of natural products with various biological activities, yet its chemical synthesis poses a challenge...

Prodigiosin is a potent cytotoxic alkaloid but lacks target selectivity. We advance functionalization of all three pyrrole rings of prodigiosin to enable site-specific conjugation via click chemistry...

Dimeric naphthopyranones are known to be biologically active, however, for the corresponding monomeric naphthopyranones this information is still elusive. Here the first enantioselective total synthesis of semi-viriditoxic acid as well as the synthesis of semi-viriditoxin and derivatives is reported …

MonocotJRLs are Poaceae-specific two-domain proteins that consist of a jacalin-related lectin (JRL) and a dirigent (DIR) domain which participate in multiple developmental processes, including disease resistance. For OsJAC1, a monocotJRL from rice, it has been confirmed that constitutive expression in transgenic rice or barley plants facilitates broad-spectrum disease resistance. In this process, both domains of OsJAC1 act cooperatively, as evidenced from experiments with artificially separated JRL- or DIR-domain-containing proteins. Interestingly, these chimeric proteins did not evolve in dicotyledonous plants. Instead, proteins with a single JRL domain, multiple JRL domains or JRL domains fused to domains other than DIR domains are present. In this study, we wanted to test if the cooperative function of JRL and DIR proteins leading to pathogen resistance was conserved in the dicotyledonous plant Arabidopsis thaliana. In Arabidopsis, we identified 50 JRL and 24 DIR proteins, respectively, from which seven single-domain JRL and two single-domain DIR candidates were selected. A single-cell transient gene expression assay in barley revealed that specific combinations of the Arabidopsis JRL and DIR candidates reduced the penetration success of barley powdery mildew. Strikingly, one of these pairs, AtJAX1 and AtDIR19, is encoded by genes located next to each other on chromosome one. However, when using natural variation and analyzing Arabidopsis ecotypes that express full-length or truncated versions of AtJAX1, the presence/absence of the full-length AtJAX1 protein could not be correlated with resistance to the powdery mildew fungus Golovinomyces orontii. Furthermore, an analysis of the additional JRL and DIR candidates in a bi-fluorescence complementation assay in Nicotiana benthamiana revealed no direct interaction of these JRL/DIR pairs. Since transgenic Arabidopsis plants expressing OsJAC1-GFP also did not show increased resistance to G. orontii, it was concluded that the resistance mediated by the synergistic activities of DIR and JRL proteins is specific for members of the Poaceae, at least regarding the resistance against powdery mildew. Arabidopsis lacks the essential components of the DIR-JRL-dependent resistance pathway.

Enzyme immobilization is a technology that enables (bio-)catalysts to be applied in continuous-flow systems. However, there is a plethora of immobilization methods available with individual advantages and disadvantages. Here, we assessed the influence of simple and readily available methods with respect to the performance of 2-deoxy-d-ribose-5-phosphate aldolase (DERA) in continuous-flow conditions. The investigated immobilization strategies cover the unspecific attachment to carriers via epoxides, affinity-based attachment via metal ion affinity, StrepTag™-StrepTactin™ interaction as well as the covalent affinity attachment of an enzyme to a matrix tethered by the HaloTag®. The metal-ion-affinity-based approach outperformed the other methods in terms of immobilized activity and stability under applied conditions. As most enzymes examined today already have a HisTag for purification purposes, effective immobilization may be applied, as simple as a standard purification, if needed.

Halogenating enzymes have evolved in considerable mechanistic diversity. The apparent need for secondary metabolism coincides with the current need to introduce halogens in synthetic products. The potential of halogenating enzymes and, especially, vanadate-dependent haloperoxidases has been insufficiently exploited for synthetic purposes. In this work, we identified potential halogenase sequences by screening algal, fungal, and protobacterial sequence databases, structural modeling of putative halogenases, and mapping and comparing active sites. In a final step, individual haloperoxidases were expressed and kinetically characterized. A vanadate-dependent haloperoxidase from Rhodoplanes roseus was heterologously expressible by E. coli and could be purified to homogeneity. The kinetic data revealed a higher turnover number than the known VClPO-CI and no inhibitory effect from bromide, rendering this enzyme a promising biocatalyst. Other predicted haloperoxidases were not expressed successfully yet but these enzymes were predicted to be present in a wide taxonomic variety.

Biocatalysis is constantly providing novel options for the synthesis of active pharmaceutical ingredients (APIs). In addition to drug development and manufacturing, biocatalysis also plays a role in drug discovery and can support many active ingredient syntheses at an early stage to build up entire scaffolds in a targeted and preparative manner. Recent progress in recruiting new enzymes by genome mining and screening or adapting their substrate, as well as product scope, by protein engineering has made biocatalysts a competitive tool applied in academic and industrial spheres. This is especially true for the advances in the field of nonribosomal peptide synthesis and enzyme cascades that are expanding the capabilities for the discovery and synthesis of new bioactive compounds via biotransformation. Here we highlight some of the most recent developments to add to the portfolio of biocatalysis with special relevance for the synthesis and late-stage functionalization of APIs, in order to bypass pure chemical processes.

Wir besetzen aktuell vier Doktorandenstellen in der (Bio)katalyse in der Durchfluss-Chemie (Flow-Chemie), der Natur- und Wirkstoffsynthese, Synthetische Enzymologie und Alkaloid-Semisynthese. Weitere Informationen gibt unter Stellenausschreibungen.

1,2,3,4-Tetrahydroisoquinolines form a valuable scaffold for a variety of bioactive secondary metabolites and commercial pharmaceuticals. Due to the harsh or complex conditions of the conventional chemical synthesis of this molecular motif, alternative mild reaction pathways are in demand. Here we present an easy-to-operate chemoenzymatic one-pot process for the synthesis of tetrahydroisoquinolines starting from benzylic alcohols and an amino alcohol. We initially demonstrate the oxidation of 12 benzylic alcohols by a laccase/TEMPO system to the corresponding aldehydes, which are subsequently integrated in a phosphate salt mediated Pictet–Spengler reaction with m-tyramine. The reaction conditions of both individual reactions were analyzed separately, adapted to each other, and a straightforward one-pot process was developed. This enables the production of 12 1,2,3,4-tetrahydroisoquinolines with yields of up to 87% with constant reaction conditions in phosphate buffer and common laboratory glass bottles without the supplementation of any additives.

Kooperationen bringen oft erfolgreiche Publikationen mit sich, so auch wieder die Zusammenarbeit mit unserem Nachbarinstitut IMET. Fabian Hogenkamp und Fabienne Hilgers aus dem IMET, gelang es, gemeinsam mit Kollegen aus beiden Instituten neue optochemische Werkzeuge für die Expressionskontrolle in E. coli zu synthetisieren, zu charakterisieren und anzuwenden. Die Ergebnisse wurden nun in ChemBioChem veröffentlicht. Wir freuen uns und gratulieren allen Beteiligten ganz herzlich.

In den zurückliegenden zwei Jahren wurden etliche Lehrveranstaltungen kurzfristig auf Onlinemodule umgestellt. Dieses Format war für uns alle neu aber mit viel Einsatz war es uns doch möglich, unseren Studierenden spannende Module anzubieten. Die Lehrpreisnominierung 2021 für Thomas Classen (Chemie für Mediziner) und Jörg Pietruszka (Enzymtechnologie I) freut uns umso mehr und macht uns unglaublich stolz. Wir möchten hiermit allen Mitwirkenden und natürlich den Studierenden ganz herzlich danken! Ohne Euren Einsatz und Eure Flexibilität wären die letzten zwei Jahre so nicht möglich gewesen.

Weitere Informationen zu unseren Aktivitäten in Forschung und Lehre finden Sie auf unserer Homepage unter https://www.iboc.hhu.de/. Wir freuen uns über Ihr Interesse zu Abschlussarbeiten, Modulen, Praktika oder Dissertationen. Kontaktieren Sie uns gerne über Sonja Meyer zu Berstenhorst via lehre-iboc@hhu.de - dann findet Ihre Mail den richtigen Weg, egal ob Sie sich für das Institut für Bioorganische Chemie oder auch für die Nachwuchsgruppe Sekundärmetabolismus-Enzymologie interessieren.

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For more than two decades, the development of potent acetylcholinesterase (AChE) inhibitors has been an ongoing task to treat dementia associated with Alzheimer’s disease and improve the pharmacokineticproperties of existing drugs. Recently, Benoit David, Pascal Schneider, Philipp Schäfer were able to identify 11 new acetylcholinesterase inhibitors with low IC50 values (as part of the joint project CKB), one of which has a 5-fold lower inhibitory concentration than the drug already in use, rivastigmine. To identify potential candidates, they used three docking-based screening methods and tested a total of 61 compounds. We express our warmest congratulations on this excellent work and the successful publication.