Regulation of Sesquiterpene Biosynthesis in Plants

甾醇和倍半萜类化合物的积累已被 与活动水平的变化相关， 异膜脂生物合成途径的分支点酶， 角鲨烯合成酶和倍半萜环化酶。 下一 一个明显的问题是，这些酶的活性是否 由酶蛋白的绝对量调节。 这两种酶都要纯化，每种酶的抗体探针 产生的，每种蛋白质的绝对量 测定 酶的亚细胞分布 两种途径共有的活性，3-羟基-3-甲基戊二酰 辅酶A还原酶，以及它们各自独特的活性， 角鲨烯合成酶和倍半萜环化酶， 在烟草细胞中测定， 生物化学方法 测量体内 放射性甲羟戊酸、异戊烯基掺入率 焦磷酸和焦磷酸法呢酯转化为甾醇， 倍半萜类化合物，随后的体外酶测定将 确定其他受监管的，因此可能限制的， 酶活性。% 植物类异戊二烯包含多种化合物， 生理重要性（即，植物生长激素），以及 农业（如。风味和香味成分）和 制药（即。口服避孕药）的兴趣。 我们 了解植物如何调节这些物质的产生 化合物仍然不完整。 拟议的工作是 检查3个假定的机制，调节生物合成的 两类类异戊二烯、甾醇和倍半萜。 这类信息应提供额外的战略 未来的基因和生物技术改进， 农业和工业用植物。**//

Accumulation of sterols and sesquiterpenoids have been correlated with changes in the activity level of particular branch point enzymes of the isopernoid biosynthetic pathway, squalene synthetase and sesquiterpene cyclase. The next obvious question is whether these enzyme activities are regulated by the absolute amounts of the enzyme proteins. Both enzymes are to be purified, antibody probes for each generated, and the absolute amount of each protein determined. The subcellular distribution of an enzyme activity common to both pathways, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and those activities unique to each, squalene synthetase and sesquiterpene cyclase, will be determined in tobacco cells fractionated by conventional biochemical methods. Experiments measuring the in vivo incorporation rate of radioactive mevalonate, isopentenyl pyrophosphate, and farnesyl pyrophosphate into sterols and sesquiterpenoids, and subsequent in vitro enzyme assays will identify other regulated, and thus potentially limiting, enzyme activities.%%% Plant isoprenoids comprise a wide range of compounds of physiological importance (ie. plant growth hormones), as well as of agricultural (ie. flavor and aroma constituents) and pharmaceutical (ie. oral contraceptives) interest. Our understanding of how plants regulate the production of these compounds is still incomplete. The proposed work is to examine 3 putative mechanisms regulating the biosynthesis of two classes of isoprenoids, sterols and sesquiterpenoids. Information of this type should provide additional strategies for the future genetic and biotechnological improvement of plants for agriculture and industry.***//