LaFever R E, Croteau R
Institute of Biological Chemistry, Washington State University, Pullman 99164-6340.
Arch Biochem Biophys. 1993 Mar;301(2):361-6. doi: 10.1006/abbi.1993.1156.
The biosynthesis of several monoterpenes from the acyclic precursor geranyl pyrophosphate requires the migration of positive charge from the isopropyl side chain into the cyclohexenoid ring of the universal alpha-terpinyl cation intermediate of the reaction. The hydride shifts responsible for charge migration in the formation of three p-menthane olefin isomers were examined in a range of plant species: alpha-terpinene in American wormseed, gamma-terpinene in thyme, and (-)-beta-phellandrene in lodgepole pine. The experimental approach utilized soluble cell-free enzyme systems and specifically labeled geranyl substrates, with the determination of the labeling patterns in the resulting cyclic products. The results were consistent with stereoelectronic features of the cyclization and support the general model for monoterpene formation.
从无环前体香叶基焦磷酸生物合成几种单萜，需要正电荷从异丙基侧链迁移到反应通用α-萜品基阳离子中间体的环己烯环中。在一系列植物物种中研究了在形成三种对薄荷烷烯烃异构体时负责电荷迁移的氢化物转移：美洲土荆芥中的α-萜品烯、百里香中的γ-萜品烯和黑松中的(-)-β-水芹烯。实验方法利用可溶性无细胞酶系统和经过特殊标记的香叶基底物，测定所得环状产物中的标记模式。结果与环化的立体电子特征一致，并支持单萜形成的一般模型。
