STEREOCHEMICAL STUDIES OF ISOPRENOID BIOSYNTHESIS

类异戊二烯生物合成的立体化学研究

• 批准号: 3277941
• 负责人: DAVID E CANE
• 金额: $ 15.75万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1982
• 资助国家: 美国
• 起止时间: 1982-01-01 至 1988-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3277941
• 关键词: allyl compound; cyclization; farnesyl compound; geranyl compound; isomerase; isoprenoid; ligase; monoterpenes; pyrophosphates; sesquiterpenes; stereochemistry; steroid biosynthesis

The allylic pyrophosphates, farnesyl geranyl pyrophosphate, are the universal acyclic procursors of sesquiterpenes and monoterpenes, respectively. Using a number of monoterpene and sesquiterpene synthetases isolated from fungi and higher plants, we plan to study the key cyclization reactions by which these widely occurring classes of isoprenoid natural products are biosynthesized. A proposed stereochemical model for the formation of six-membered ring-containing sesquiterpenes, involving the intermediacy of the tertiary allylic pyrophosphate nerolidyl pyrophosphate will be tested by the use of trichodiene synthetase and appropriately 3H- and 14C-labeled farnesyl and nerolidyl pyrophosphate substrates, allowing us to define the conformation of the cyclizing substrates as well as the role played by the pyrophosphate ion. The mechanism of the proposed isomerization--cyclization sequence leading to formation of trichodiene will be further investigated by comparing the mechanism of action of trichodiene synthetase with that of farnesyl pyrophosphate isomerase. The latter enzyme catalyzes the isomerization of farnesyl of nerolidyl pyrophosphate. By using a series of selected substrate analogs, we will attempt to factor the trichodiene synthetase reaction into its component transformations of isomerization and cyclization. We plan to study the stereochemical details of a second cyclization reaction, the enzymatic transformation of farnesyl pyrophosphate to the sequiterpene humulene, catalyzed by a cyclase isolated from sage. We have been testing a stereochemical model of monoterpene biosynthesis, using a variety of monoterpene synthetases. Incorporations of various labeled precursors, including linalyl pyrophosphate, are planned which will allow us to elucidate the detailed structure and conformation of the reactive intermediates of monoterpene biosynthesis. It is expected that the work proposed will lead to the development of new techniques for the study of natural products biosynthesis and that the information gained from these studies will be applicable to an understanding of the catalysis of biological carbon-carbon bond formation in general.

焦磷酸烯丙酯，即焦磷酸法呢基香叶基酯， 倍半萜和单萜的通用无环前体， 分别 使用许多单萜和倍半萜合成酶 从真菌和高等植物中分离，我们计划研究关键环化 这些广泛存在的类异戊二烯天然产物的反应 产品是生物合成的。 六元环生成的立体化学模型 含环的倍半萜，涉及三级结构的中间性 烯丙基焦磷酸橙花苷焦磷酸将通过使用 β-二烯合成酶和适当的3 H-和14 C-标记的法呢基， 橙花苷焦磷酸底物，使我们能够定义构象 以及焦磷酸盐所起的作用 离子。 提出的异构化-环化序列的机制 将通过以下方法进一步研究导致形成顺丁烯二烯的反应： 比较了双烯合成酶与 法呢焦磷酸异构酶。 后一种酶催化 橙花苷焦磷酸法呢基异构化。 通过使用一系列 选择底物类似物，我们将尝试因子β-二烯 合成酶反应转化成异构化的组分， 环化反应 我们计划研究第二个 环化反应，法呢基的酶促转化 焦磷酸的sequiterpene蛇麻烯，催化的环化酶分离 来自Sage 我们一直在测试单萜的立体化学模型 生物合成，使用多种单萜合成酶。 立案法 各种标记的前体，包括焦磷酸芳樟酯， 这将使我们能够阐明的详细结构和构象的 单萜生物合成的活性中间体。 预计 建议的工作将导致新技术的发展， 研究天然产物的生物合成， 从这些研究将适用于理解的催化 生物碳-碳键形成的关键。