Isotopologue Profiling of Triterpene Formation under Physiological Conditions. Biosynthesis of Lupeol-3-(3鈥?R-hydroxy)-stearate in Pentalinon andrieuxii

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• 作者：Luis M. Pe帽a-Rodr铆guez ; Alejandro Yam-Puc ; Nihat Knispel ; Nicholas Schramek ; Claudia Huber ; Christoph Gra脽berger ; Fabiola G. Ram铆rez-Torres ; Fabiola Escalante-Erosa ; Karlina Garc铆a-Sosa ; Mickel R. Hiebert-Giesbrecht ; Manuel J. Chan-Bacab ; Gregorio Godoy-Hern谩ndez ; Adelbert Bacher ; Wolfgang Eisenreich
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：April 4, 2014
• 年：2014
• 卷：79
• 期：7
• 页码：2864-2873
• 全文大小：511K
• 年卷期：v.79,no.7(April 4, 2014)
• ISSN：1520-6904

文摘

The biosynthesis of lupeol-3-(3鈥?i>R-hydroxy)-stearate (procrim b, 1) was investigated in the Mexican medicinal plant Pentalinon andrieuxii by ¹³CO₂ pulse-chase experiments. NMR analyses revealed positional enrichments of ¹³C₂-isotopologues in both the triterpenoid and the hydroxystearate moieties of 1. Five of the six isoprene units reflected a pattern with [1,2-¹³C₂]- and [3,5-¹³C₂]-isotopologues from the respective C₅-precursors, IPP and DMAPP, whereas one isoprene unit in the ring E of 1 showed only the [3,5-¹³C₂]-connectivity of the original C₅-precursor, due to rearrangement of the dammarenyl cation intermediate during the cyclization process. The presence of ¹³C₂-isotopologues was indicative of [¹³C₂]acetyl-CoA being the precursor units in the formation of the fatty acid moiety and of the triterpene via the mevalonate route. The observed labeling pattern was in agreement with a chair-chair-chair-boat conformation of the (S)-2,3-oxidosqualene precursor during the cyclization process, suggesting that the lupeol synthase from P. andrieuxii is of the same type as that from Olea europea and Taraxacum officinale, but different from that of Arabidopsis thaliana. The study shows that ¹³CO₂ pulse-chase experiments are powerful in elucidating, under in vivo conditions and in a single experiment, the biosynthesis of complex plant products including higher terpenes.