Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Mittersteiner, M.; Pereira, G. S.; Silva, Y.; Wessjohann, L. A.; Bonacorso, H. G.; Martins, M. A. P.; Zanatta, N.;Substituent-driven selective N-/O-alkylation of 4-(trihalomethyl)pyrimidin-2(1H)-ones using brominated enonesJ. Org. Chem.874590-4602(2022)DOI: 10.1021/acs.joc.1c02919
The selective N- or O-alkylation of 4-(trihalomethyl)-pyrimidin-2(1H)-ones, using 5-bromo enones/enaminones as alkylating agents, is reported. It was found that the selectivity toward the N-or O-regioisomer is driven by the substituent present at the 6-position of the pyrimidine ring, thus enabling the preparation of each isomer as the sole product, in 60−95% yields. Subsequent cyclocondensation of the enaminone moiety with nitrogen dinucleophiles led to pyrimidine−azole conjugates in 55−83% yields.
Publikation
Trempel, F.; Eschen‐Lippold, L.; Bauer, N.; Ranf, S.; Westphal, L.; Scheel, D.; Lee, J.;A mutation in Asparagine‐Linked Glycosylation 12 (ALG12) leads to receptor misglycosylation and attenuated responses to multiple microbial elicitorsFEBS Lett.5942440-2451(2020)DOI: 10.1002/1873-3468.13850
Changes in cellular calcium levels are one of the earliest signalling events in plants exposed to pathogens or other exogenous factors. In a genetic screen, we identified an Arabidopsis thaliana ‘changed calcium elevation 1 ’ (cce1 ) mutant with attenuated calcium response to the bacterial flagellin flg22 peptide and several other elicitors. Whole genome re‐sequencing revealed a mutation in ALG12 (Asparagine‐Linked Glycosylation 12 ) that encodes the mannosyltransferase responsible for adding the eighth mannose residue in an α‐1,6 linkage to the dolichol‐PP‐oligosaccharide N ‐glycosylation glycan tree precursors. While properly targeted to the plasma membrane, misglycosylation of several receptors in the cce1 background suggests that N ‐glycosylation is required for proper functioning of client proteins.
Publikation
Puentes, A. R.; Neves Filho, R. A. W.; Rivera, D. G.; Wessjohann, L. A.;Total Synthesis of Cordyheptapeptide ASynlett281971-1974(2017)DOI: 10.1055/s-0036-1588433
The first total synthesis of cordyheptapeptide A is described. The synthesis is accomplished by a convergent approach featuring a combination of peptide coupling and the Ugi reaction for the preparation of the main building blocks and the acyclic precursor. The assembly of an N-methylated fragment by the Ugi reaction comprised the utilization of a convertible isonitrile followed by activation of the C-terminal amide. Two different macrocyclization sites were evaluated, proving greater efficacy the macrolactamization at the site Ile-Tyr, likely due of a more suitable conformational bias of the acyclic precursor having an internal β-turn centered at the N-Me-d-Phe-Pro moiety.
Publikation
Wessjohann, L. A.; Morejon, M. C.; Ojeda, G. M.; Rhoden, C. R. B.; Rivera, D. G.;Applications of Convertible Isonitriles in the Ligation and Macrocyclization of Multicomponent Reaction-Derived Peptides and DepsipeptidesJ. Org. Chem.816535-6545(2016)DOI: 10.1021/acs.joc.6b01150
Peptide ligation and macrocyclization are among the most relevant approaches in the field of peptide chemistry. Whereas a variety of strategies relying on coupling reagents and native chemical ligation are available, there is a continuous need for efficient peptide ligation and cyclization methods. Herein we report on the utilization of convertible isonitriles as effective synthetic tools for the ligation and macrocyclization of peptides arising from isocyanide-based multicomponent reactions. The strategy relies on the use of convertible isonitriles—derived from Fukuyama amines—and peptide carboxylic acids in Ugi and Passerini reactions to afford N-alkylated peptides and depsipeptides, respectively, followed by conversion of the C-terminal amide onto either N-peptidoacyl indoles or pyrroles. Such activated peptides proved efficient in the ligation to peptidic, lipidic and fluorescently labeled amines and in macrocyclization protocols. As a result, a wide set of N-substituted peptides (with methyl, glycosyl and amino acids as N-substituents), cyclic N-methylated peptides and a depsipeptide were produced in good yields using conditions that involve either classical heating or microwave irradiation. This report improves the repertoire of peptide covalent modification methods by exploiting the synthetic potential of multicomponent reactions and convertible isonitriles.