Biosynthesis of Germacrene A Carboxylic Acid in Chicory Roots. Demonstration of a Cytochrome P450 (+)-Germacrene A Hydroxylase and NADP+-Dependent Sesquiterpenoid Dehydrogenase(s) Involved in Sesquiterpene Lactone Biosynthesis
作者:Jan-Willem de Kraker、Maurice C. R. Franssen、Marcella C. F. Dalm、Aede de Groot、Harro J. Bouwmeester
DOI:10.1104/pp.125.4.1930
日期:2001.4.1
Sprouts of chicory (Cichorium intybus), a vegetable grown in the dark, have a slightly bitter taste associated with the presence of guaianolides, eudesmanolides, and germacranolides. The committed step in the biosynthesis of these compounds is catalyzed by a (+)-germacrene A synthase. Formation of the lactone ring is the postulated next step in biosynthesis of the germacrene-derived sesquiterpene lactones
菊苣芽(Cichorium intybus)是一种在黑暗中生长的蔬菜,其味道略带苦味,与愈创木酚内酯、eudesmanolides 和 Germacranolides 的存在有关。这些化合物生物合成的关键步骤是由 (+)-germacrene A 合酶催化的。内酯环的形成是假设的衍生于锗烯的倍半萜内酯生物合成的下一步。本研究通过从菊苣根中分离酶活性证实了这一假设,该酶活性在germacrene A异丙烯基侧链中引入了羧酸功能,这对于内酯环的形成是必需的。 (+)-germacrene A 通过细胞色素 P450 酶羟基化为 germacra-1(10),4,11(13)-trien-12-ol,随后氧化为 germacra-1(10),4,11( 13)-trien-12-oic 酸通过 NADP+ 依赖性脱氢酶产生。两种氧化的锗烯均被检测为它们的 Cope 重排产物 elema-1,3,11(13)-trien-12-ol