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…
Zanatta, N.; Mittersteiner, M.; Aquino, E. C.; Budragchaa, T.; Wessjohann, L. A.; Bonacorso, H. G.; Martins, M. A. P.;Synthesis of methylene-bridged trifluoromethyl azoles using 5-(1,2,3-Triazol-1-yl)enonesSynthesis54439-450(2022)DOI: 10.1055/s-0040-1719837
A protocol for synthesizing triazole-containing pyrazolines and pyrazoles selectively using trifluoromethylated 5-(1,2,3-triazol-1-yl)enones as starting materials, is reported. The selectivity of the reaction was controlled by the nature of the hydrazine or derivative used: free hydrazines furnished the 1,5-regiosiomer exclusively in yields up to 98%, whereas protected hydrazines provided the 1,3-regioisomer in yields up to 77%. To demonstrate the synthetic versatility of the triazole-based enone, reactions with other unsymmetrical dinucleophiles (hydroxylamine hydrochloride and S-methyl isothiourea sulfates) allowed the selective preparation of triazole-containing isoxazoline and pyrimidine rings.
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
Ruttkies, C.; Schymanski, E. L.; Strehmel, N.; Hollender, J.; Neumann, S.; Williams, A. J.; Krauss, M.;Supporting non-target identification by adding hydrogen deuterium exchange MS/MS capabilities to MetFragAnal. Bioanal. Chem.4114683-4700(2019)DOI: 10.1007/s00216-019-01885-0
Liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) is increasingly popular for the non-targeted exploration of complex samples, where tandem mass spectrometry (MS/MS) is used to characterize the structure of unknown compounds. However, mass spectra do not always contain sufficient information to unequivocally identify the correct structure. This study investigated how much additional information can be gained using hydrogen deuterium exchange (HDX) experiments. The exchange of “easily exchangeable” hydrogen atoms (connected to heteroatoms), with predominantly [M+D]+ ions in positive mode and [M-D]− in negative mode was observed. To enable high-throughput processing, new scoring terms were incorporated into the in silico fragmenter MetFrag. These were initially developed on small datasets and then tested on 762 compounds of environmental interest. Pairs of spectra (normal and deuterated) were found for 593 of these substances (506 positive mode, 155 negative mode spectra). The new scoring terms resulted in 29 additional correct identifications (78 vs 49) for positive mode and an increase in top 10 rankings from 80 to 106 in negative mode. Compounds with dual functionality (polar head group, long apolar tail) exhibited dramatic retention time (RT) shifts of up to several minutes, compared with an average 0.04 min RT shift. For a smaller dataset of 80 metabolites, top 10 rankings improved from 13 to 24 (positive mode, 57 spectra) and from 14 to 31 (negative mode, 63 spectra) when including HDX information. The results of standard measurements were confirmed using targets and tentatively identified surfactant species in an environmental sample collected from the river Danube near Novi Sad (Serbia). The changes to MetFrag have been integrated into the command line version available at http://c-ruttkies.github.io/MetFrag and all resulting spectra and compounds are available in online resources and in the Electronic Supplementary Material (ESM).
Publikation
Hu, M.; Müller, E.; Schymanski, E. L.; Ruttkies, C.; Schulze, T.; Brack, W.; Krauss, M.;Performance of combined fragmentation and retention prediction for the identification of organic micropollutants by LC-HRMSAnal. Bioanal. Chem.4101931-1941(2018)DOI: 10.1007/s00216-018-0857-5
In nontarget screening, structure elucidation of small molecules from high resolution mass spectrometry (HRMS) data is challenging, particularly the selection of the most likely candidate structure among the many retrieved from compound databases. Several fragmentation and retention prediction methods have been developed to improve this candidate selection. In order to evaluate their performance, we compared two in silico fragmenters (MetFrag and CFM-ID) and two retention time prediction models (based on the chromatographic hydrophobicity index (CHI) and on log D). A set of 78 known organic micropollutants was analyzed by liquid chromatography coupled to a LTQ Orbitrap HRMS with electrospray ionization (ESI) in positive and negative mode using two fragmentation techniques with different collision energies. Both fragmenters (MetFrag and CFM-ID) performed well for most compounds, with average ranking the correct candidate structure within the top 25% and 22 to 37% for ESI+ and ESI− mode, respectively. The rank of the correct candidate structure slightly improved when MetFrag and CFM-ID were combined. For unknown compounds detected in both ESI+ and ESI−, generally positive mode mass spectra were better for further structure elucidation. Both retention prediction models performed reasonably well for more hydrophobic compounds but not for early eluting hydrophilic substances. The log D prediction showed a better accuracy than the CHI model. Although the two fragmentation prediction methods are more diagnostic and sensitive for candidate selection, the inclusion of retention prediction by calculating a consensus score with optimized weighting can improve the ranking of correct candidates as compared to the individual methods.