咖啡碱合成N-甲基转移酶研究进展

Research Progress of N-methyltransferases Involved in Caffeine Biosynthesis

咖啡碱是茶叶、咖啡等饮料的主要品质成分及功能成分之一。在植物体内咖啡碱生物合成的核心途径为:黄嘌呤核苷→7-甲基黄嘌呤核苷→7-甲基黄嘌呤→可可碱→咖啡碱,其中包括3步由N-甲基转移酶催化的转甲基化反应和1步由核糖核苷水解酶催化的脱核苷反应。N-甲基转移酶是参与咖啡碱生物合成的关键酶类。介绍了植物中咖啡碱的基本情况及其生物合成途径,重点综述了咖啡碱合成N-甲基转移酶的酶学特性、NMTs的克隆、基因结构与功能的关系以及基因表达调控研究等方面国内外的研究进展,并对未来该领域的研究重点进行了探讨和展望。

Caffeine is one of the main quality and functional components in beverage such as tea, coffee, etc. At present, a xanthosine→7-methylxanthosine→7-methylxanthine→theobromine→caffeine pathway is supported as the major route to caffeine, and it is synthesized through three methylation reactions by N- methyltransferase and a nucleosidase reaction by nucleoside hydrolase. N- methyltransferases（NMTs） are important enzymes in caffeine synthesis process. In this paper, the profile of caffeine in plant and the pathway of caffeine synthesis were introduced, and the research progress on the enzymology properties, gene cloning and expression, the relationship of gene function and structure of NMTs involved in caffeine biosynthesis were mainly reviewed. Finally, the research emphasis in the field for the future was discussed and prospected.