The development of potent adjuvants is an important step for improving the performance of subunit vaccines. CD1d agonists, such as the prototypical α‐galactosyl ceramide (α‐GalCer), are of special interest due to their ability to activate iNKT cells and trigger rapid dendritic cell maturation and B‐cell activation. Herein, we introduce a novel derivatization hotspot at the α‐GalCer skeleton, namely the N‐substituent at the amide bond. The multicomponent diversification of this previously unexplored glycolipid chemotype space permitted the introduction of a variety of extra functionalities that can either potentiate the adjuvant properties or serve as handles for further conjugation to antigens toward the development of self‐adjuvanting vaccines. This strategy led to the discovery of compounds eliciting enhanced antigen‐specific T cell stimulation and a higher antibody response when delivered by either the parenteral or the mucosal route, as compared to a known potent CD1d agonist. Notably, various functionalized α‐GalCer analogues showed a more potent adjuvant effect after intranasal immunization than a PEGylated α‐GalCer analogue previously optimized for this purpose. Ultimately, this work could open multiple avenues of opportunity for the use of mucosal vaccines against microbial infections.

Fungal unspecific peroxygenases (UPOs) have gained substantial attention for their versatile oxyfunctionalization chemistry paired with impressive catalytic capabilities. A major drawback, however, remains their sensitivity towards their co‐substrate hydrogen peroxide, necessitating the use of smart in situ hydrogen peroxide generation methods to enable efficient catalysis setups. Herein, we introduce flavin‐containing protein photosensitizers as a new general tool for light‐controlled in situ hydrogen peroxide production. By genetically fusing flavin binding fluorescent proteins and UPOs, we have created two virtually self‐sufficient photo‐enzymes (PhotUPO). Subsequent testing of a versatile substrate panel with the two divergent PhotUPOs revealed two stereoselective conversions. The catalytic performance of the fusion protein was optimized through enzyme and substrate loading variation, enabling up to 24300 turnover numbers (TONs) for the sulfoxidation of methyl phenyl sulfide. The PhotUPO concept was upscaled to a 100 mg substrate preparative scale, enabling the extraction of enantiomerically pure alcohol products.Graphical Abstract Unspecific peroxygenases (UPOs) have recently gained attraction as versatile oxyfunctionalization catalysts. One shortcoming, however, is their susceptibility towards the co-substrate hydrogen peroxide. As a solution, the concept of light-dependent UPO biocatalysis with genetically encoded flavin-containing photosensitizer proteins for in situ hydrogen peroxide production is introduced.

Research data management (RDM) is needed to assist experimental advances and data collection in the chemical sciences. Many funders require RDM because experiments are often paid for by taxpayers and the resulting data should be deposited sustainably for posterity. However, paper notebooks are still common in laboratories and research data is often stored in proprietary and/or dead-end file formats without experimental context. Data must mature beyond a mere supplement to a research paper. Electronic lab note-books (ELN) and laboratory information managementsystems (LIMS) allow researchers to manage data better and they simplify research and publication. Thus, an agreement is needed on minimum information standards for data handling to support structured approaches to data reporting. As digitalization becomes part of curricular teaching, future generations of digital native chemists will embrace RDM and ELN as an organic part of their research.

’Candidatus Phytoplasma mali’, is a bacterial pathogen associated with the so-called apple proliferation disease in Malus × domestica. The pathogen manipulates its host with a set of effector proteins, among them SAP11CaPm, which shares similarity to SAP11AYWB from ’Candidatus Phytoplasma asteris’. SAP11AYWB interacts and destabilizes the class II CIN transcription factors of Arabidopsis thaliana, namely AtTCP4 and AtTCP13 as well as the class II CYC/TB1 transcription factor AtTCP18, also known as BRANCHED1 being an important factor for shoot branching. It has been shown that SAP11CaPm interacts with the Malus × domestica orthologues of AtTCP4 (MdTCP25) and AtTCP13 (MdTCP24), but an interaction with MdTCP16, the orthologue of AtTCP18, has never been proven. The aim of this study was to investigate this potential interaction and close a knowledge gap regarding the function of SAP11CaPm. A Yeast two-hybrid test and Bimolecular Fluorescence Complementation in planta revealed that SAP11CaPm interacts with MdTCP16. MdTCP16 is known to play a role in the control of the seasonal growth of perennial plants and an increase of MdTCP16 gene expression has been detected in apple leaves in autumn. In addition to this, MdTCP16 is highly expressed during phytoplasma infection. Binding of MdTCP16 by SAP11CaPm might lead to the induction of shoot proliferation and early bud break, both of which are characteristic symptoms of apple proliferation disease.

In contrast to the myriad of methods available to produce α‐helices and antiparallel β‐sheets in synthetic peptides, just a few are known for the construction of stable, non‐cyclic parallel β‐sheets. Herein, we report an efficient on‐resin approach for the assembly of parallel β‐sheet peptides in which the N‐alkylated turn moiety enhances the stability and gives access to a variety of functionalizations without modifying the parallel strands. The key synthetic step of this strategy is the multicomponent construction of an N‐alkylated turn using the Ugi reaction on varied isocyano‐resins. This four‐component process assembles the orthogonally protected turn fragment and incorporates handles serving for labeling/conjugation purposes or for reducing peptide aggregation. NMR and circular dichroism analyses confirm the better‐structured and more stable parallel β‐sheets in the N‐alkylated peptides compared to the non‐functionalized variants.

Atypical myopathy (AM) in horses is caused by ingestion of seeds of the Acer species (Sapindaceae family). Methylenecyclopropylacetyl-CoA (MCPA-CoA), derived from hypoglycin A (HGA), is currently the only active toxin in Acer pseudoplatanus or Acer negundo seeds related to AM outbreaks. However, seeds or arils of various Sapindaceae (e.g., ackee, lychee, mamoncillo, longan fruit) also contain methylenecyclopropylglycine (MCPG), which is a structural analogue of HGA that can cause hypoglycaemic encephalopathy in humans. The active poison formed from MCPG is methylenecyclopropylformyl-CoA (MCPF-CoA). MCPF-CoA and MCPA-CoA strongly inhibit enzymes that participate in β-oxidation and energy production from fat. The aim of our study was to investigate if MCPG is involved in Acer seed poisoning in horses. MCPG, as well as glycine and carnitine conjugates (MCPF-glycine, MCPF-carnitine), were quantified using high-performance liquid chromatography-tandem mass spectrometry of serum and urine from horses that had ingested Acer pseudoplatanus seeds and developed typical AM symptoms. The results were compared to those of healthy control horses. For comparison, HGA and its glycine and carnitine derivatives were also measured. Additionally, to assess the degree of enzyme inhibition of β-oxidation, several acyl glycines and acyl carnitines were included in the analysis. In addition to HGA and the specific toxic metabolites (MCPA-carnitine and MCPA-glycine), MCPG, MCPF-glycine and MCPF-carnitine were detected in the serum and urine of affected horses. Strong inhibition of β-oxidation was demonstrated by elevated concentrations of all acyl glycines and carnitines, but the highest correlations were observed between MCPF-carnitine and isobutyryl-carnitine (r = 0.93) as well as between MCPA- (and MCPF-) glycine and valeryl-glycine with r = 0.96 (and r = 0.87). As shown here, for biochemical analysis of atypical myopathy of horses, it is necessary to take MCPG and the corresponding metabolites into consideration.

For the first time, the Petasis (borono‐Mannich) reaction is employed for the multicomponent labeling and stapling of peptides. The report includes the solid‐phase derivatization of peptides at the N‐terminus, Lys, and Nϵ‐MeLys side‐chains by an on‐resin Petasis reaction with variation of the carbonyl and boronic acid components. Peptides were simultaneously functionalized with aryl/vinyl substituents bearing fluorescent/affinity tags and oxo components such as dihydroxyacetone, glyceraldehyde, glyoxylic acid, and aldoses, thus encompassing a powerful complexity‐generating approach without changing the charge of the peptides. The multicomponent stapling was conducted in solution by linking Nϵ‐MeLys or Orn side‐chains, positioned at i, i+7 and i, i+4, with aryl tethers, while hydroxy carbonyl moieties were introduced as exocyclic fragments. The good efficiency and diversity oriented character of these methods show prospects for peptide drug discovery and chemical biology.

The functionalization of C−H bonds with non‐precious metal catalysts is an important research area for the development of efficient and sustainable processes. Herein, we describe the development of iron porphyrin catalyzed reactions of diazoacetonitrile with N‐heterocycles yielding important precursors of tryptamines, along with experimental mechanistic studies and proof‐of‐concept studies of an enzymatic process with YfeX enzyme. By using readily available FeTPPCl, we achieved the highly efficient C−H functionalization of indole and indazole heterocycles. These transformations feature mild reaction conditions, excellent yields with broad functional group tolerance, can be conducted on gram scale, and thus provide a unique streamlined access to tryptamines.

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Glucosinolates, a group of sulfur-rich thioglucosides found in plants of the order Brassicales, have attracted a lot of interest as chemical defenses of plants and health promoting substances in human diet. They are accumulated separately from their hydrolyzing enzymes, myrosinases, within the intact plant, but undergo myrosinase-catalyzed hydrolysis upon tissue disruption. This results in various biologically active products, e.g. isothiocyanates, simple nitriles, epithionitriles, and organic thiocyanates. While formation of isothiocyanates proceeds by a spontaneous rearrangement of the glucosinolate aglucone, aglucone conversion to the other products involves specifier proteins under physiological conditions. Specifier proteins appear to act with high specificity, but their exact roles and the structural bases of their specificity are presently unknown. Previous research identified the motif EXXXDXXXH as potential iron binding site required for activity, but crystal structures of recombinant specifier proteins lacked the iron cofactor. Here, we provide experimental evidence for the presence of iron (most likely Fe2+) in purified recombinant thiocyanate-forming protein from Thlaspi arvense (TaTFP) using a Ferene S-based photometric assay as well as Inductively Coupled Plasma-Mass Spectrometry. Iron binding and activity depend on E266, D270, and H274 suggesting a direct interaction of Fe2+ with these residues. Furthermore, we demonstrate presence of iron in epithiospecifier protein and nitrile-specifier protein 3 from Arabidopsis thaliana (AtESP and AtNSP3). We also present a homology model of AtNSP3. In agreement with this model, iron binding and activity of AtNSP3 depend on E386, D390, and H394. The homology model further suggests that the active site of AtNSP3 imposes fewer restrictions to the glucosinolate aglucone conformation than that of TaTFP and AtESP due to its larger size. This may explain why AtNSP3 does not support epithionitrile or thiocyanate formation, which likely requires exact positioning of the aglucone thiolate relative to the side chain.