Occurrence of Cationic Intermediates and Deficient Control during the Enzymatic Cyclization of Squalene to Hopanoids.
Occurrence of Cationic Intermediates and Deficient Control during the Enzymatic Cyclization of Squalene to Hopanoids.
复制标题
角鲨烯酶促环化为藿香类化合物过程中阳离子中间体的出现和控制不足。
作者：
C. Pale;C. Feil;M. Rohmer;K. Poralla
四环三萜（例如，3）是角鲨烯(1)被角鲨烯/藿烯环化酶环化的次要产物；它们也在体内被发现。这些副产物的鉴定为藿烷骨架的复杂生物合成提供了新的见解，并证明酶对无环底物角鲨烯的构象没有绝对控制，而四环和五环碳阳离子中间体（例如，2）参与了环化过程。
Tetracyclic triterpenes (for example, 3) are formed as minor products of the cyclization of squalene (1) by squalene/hopene cyclase; they have also been found in vivo. The identification of these side products offers new insight into the complex biosynthesis of the hopane skeleton, and proves that the enzyme has no absolute control of the conformation of the acyclic substrate squalene and that tetra- and pentacyclic carbocationic intermediates are involved (for example, 2) in the cyclization process.