Metabolism of Isoleucine to Insect Juvenile Hormone II via Propionyl-Coenzyme A

研究表明，异亮氨酸和缬氨酸提供丙酸单位，专门用于乙基分枝保幼激素(JHS)的生物合成。不容易代谢的昆虫小体(鳞翅目的小体)分泌丙酸和乙基支链的JHS。这项研究将扩展这些研究，并确定是什么允许CA违反倍半萜类化合物的生物合成规则，并将丙酰辅酶A结合到这一途径中。ıU-14c！异亮氨酸将在昆虫的几个组织中进行检测，这些组织产生乙基分支的JHS与只产生JH III的组织。这些数据对于解释物种之间的新陈代谢差异很重要。此外，ıU-14c！分离的线粒体中的异亮氨酸也将被研究。这项工作将确定是否存在从线粒体输出丙酰辅酶A的有效运输系统。肉碱丙酰转移酶和柠檬酸甲酯的形成将被视为丙酰辅酶A转运的可能可能性。如果丙酸转运的独特系统不能解释这种现象，将调查某些酶可能位于不同的亚细胞细胞器中，而不是通常认为存在的那些亚细胞细胞器。保幼激素是昆虫纲成员分泌的一组结构相关的化合物，具有形态发生和促性腺活性。重要的是要了解有关代谢途径的基本知识，以了解昆虫为什么以及如何能够合成这些荷尔蒙。了解这一途径的生化细节可以为合成专门抑制它的化学物质指明方向。对于包括飞蛾在内的昆虫来说，这些化学物质将是抗荷尔蒙(因此，也可能是特定的杀虫剂)，而飞蛾是最具破坏性的农作物害虫之一。

It has been shown that isoleucine and valine supply propionate units used specifically for the biosynthesis of the ethyl-branched juvenile hormones (JHs). Insect corpora allata (CA) which do not metabolize them readily (the CA of Lepidoptera) secrete propionate and ethyl-branched JHs. This research will extend these studies and determine what allows the CA to violate the rules of sesquiterpenoid biosynthesis and to incorporate propionyl-CoA into this pathway. The metabolism of ıU-14c! isoleucine will be examined in several tissues of insects which make the ethyl-branched JHs vs. those that produce only JH III. These data are important for interpreting metabolic differences between species. In addition, the metabolism of ıU-14c! isoleucine in isolated mitochondria will also be studied. This work will determine whether or not there is an efficient transport system for exporting propionyl-CoA from the mitochondria. Carnitine propionyl transferase and methyl citrate formation will be examined as likely possibilities for propionyl CoA transport. If this phenomenon cannot be explained by a unique system for propionate transport, the possibility will be investigated that certain enzymes might be located in different subcellular organelles than those in which they are generally held to exist. Juvenile hormones are a group of structurally related compounds secreted by members of the class Insecta and which possess morphogenetic and gonadotropic activity. It is important to have a basic knowledge of the metabolic pathways involved to understand why and how insects are able to synthesize these hormones. Knowledge of the biochemical details of this pathway could point the way towards synthesis of chemicals which specifically inhibit it. These chemicals would be antihormones (and probably, therefore, specific insecticides) to the order of insects that includes moths, which are some of the most damaging of crop pests.