Unprecedented Occurrence of Isoaspartic Acid in a Plant Cyclopeptide

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• 作者：Damien Lacroix ; Soizic Prado ; Dennis Kamoga ; John Kasenene ; S茅verine Zirah ; Bernard Bodo
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：January 20, 2012
• 年：2012
• 卷：14
• 期：2
• 页码：576-579
• 全文大小：229K
• 年卷期：v.14,no.2(January 20, 2012)
• ISSN：1523-7052

文摘

Three structurally related cycloheptapeptides, cyclocitropsides A鈥揅, have been isolated from a MeOH extract of the root bark of Citropsis articulata, a medicinal plant in Uganda. Their sequences were elucidated on the basis of their MS/MS fragmentation, extensive 2D-NMR, chemical degradation, and biochemical modifications. Surprisingly, the sequence of cyclocitropside C differed from that of cyclocitropside B only by an Asp<sup>5sup>/isoAsp<sup>5sup> substitution. This is the first report of an isoAsp residue in a plant cyclic peptide.