Institute of Biological Chemistry and M. J. Murdock Metabolomics Laboratory, Washington State University, Pullman, WA, 99164-7411, USA.
Physical and Computational Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
Plant J. 2024 Jul;119(1):28-55. doi: 10.1111/tpj.16743. Epub 2024 Apr 2.
Monoterpene synthases (MTSs) catalyze the first committed step in the biosynthesis of monoterpenoids, a class of specialized metabolites with particularly high chemical diversity in angiosperms. In addition to accomplishing a rate enhancement, these enzymes manage the formation and turnover of highly reactive carbocation intermediates formed from a prenyl diphosphate substrate. At each step along the reaction path, a cationic intermediate can be subject to cyclization, migration of a proton, hydride, or alkyl group, or quenching to terminate the sequence. However, enzymatic control of ligand folding, stabilization of specific intermediates, and defined quenching chemistry can maintain the specificity for forming a signature product. This review article will discuss our current understanding of how angiosperm MTSs control the reaction environment. Such knowledge allows inferences about the origin and regulation of chemical diversity, which is pertinent for appreciating the role of monoterpenoids in plant ecology but also for aiding commercial efforts that harness the accumulation of these specialized metabolites for the food, cosmetic, and pharmaceutical industries.
单萜合酶（MTS）催化单萜类化合物生物合成的第一步，单萜类化合物是一类在被子植物中具有特别高的化学多样性的特殊代谢物。除了实现速率增强外，这些酶还管理着从 prenyl diphosphate 底物形成的高反应性碳正离子中间体的形成和转化。在反应路径的每一步，阳离子中间体都可能经历环化、质子、氢化物或烷基的迁移，或淬灭以终止序列。然而，酶对配体折叠的控制、特定中间体的稳定以及定义明确的淬灭化学可以保持形成标志性产物的特异性。本文综述讨论了我们目前对被子植物 MTS 如何控制反应环境的理解。这种知识允许对化学多样性的起源和调节进行推断，这对于理解单萜类化合物在植物生态学中的作用很重要，也有助于商业努力，利用这些特殊代谢物的积累，为食品、化妆品和制药行业服务。
