Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
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…
Stehle, F.; Götsch, F.; Wray, V.; Schmidt, J.; Strack, D.; Brandt, W.;Snap-shot of Serine Carboxypeptidase-like Acyltransferase Evolution: The Loss of Conserved Disulphide Bridge is Responsible for the Completion of Neo-functionalizationJ. Phylogenet. Evol. Biol.1115(2013)DOI: 10.4172/2329-9002.1000115
In this work, it is shown that the At2g23010 gene product encodes 1-O-sinapoyl-β-glucose:1-O-sinapoyl-β-glucose sinapoyltransferase (SST). In contrast to all other functional characterized acyltransferases, the SST protein is highly specific towards this reaction only, and the substrate specificity was correlated to one amino acid substitution. Detailed sequence analysis revealed the lack of the disulphide bond S1 (C78 and C323 in the SMT (sinapoylglucose:malate sinapoyltransferase), that is in SST C80 and D327). The reconstitution of this disulphide bond led to an enzyme accepting many different substrates including disaccharides. Interestingly, the overall changes within the model structures are not very dramatic, but nevertheless, the enzyme models provide some explanations for the broadened substrate specificity: the reconstitution of the disulphide bond provoked more space within the substrate binding pocket simultaneously avoiding electrostatic repulsion. As the SST sequence of A. lyrata also showed the same mutation, the loss of the disulphide bond should has arisen at least 10 mya ago. A Ka/Ks ratio ≤ 1 supports the hypothesis that the loss of this disulphide bond was rather a specification towards a certain reaction than the beginning of a gene death. At the same time, this is also associated with the fixation in the genome.
Publikation
Kolbe, A.; Porzel, A.; Schmidt, J.; Adam, G.;A new synthesis of [26,28-2H6]brassinolide and [26,28-2H6]castasterone via an unusual methyl migrationJ. Label. Compd. Rad.46231-242(2003)DOI: 10.1002/jlcr.662
Deuterium‐labelled brassinosteroids, namely [26,28‐2H6]castasterone, 8 , and [26,28‐2H6]brassinolide, 9 , were synthesized starting from 6,6‐ ethylenedioxy‐20‐formyl‐2α,3α‐isopropylidenedioxy‐5α‐pregnane, 1 , and 3‐[2H3]methyl‐but‐1‐yne‐[4,4,4‐2H3], 11 . Upon alkylating cleavage of the epoxide 6 with trimethylaluminium‐n‐butyllithium an unusual migration of a neighbouring [2H3]methyl group takes place to afford deuteriation at positions 26 and 28.