Department of Biochemistry, Saarland University, Saarbrücken, Germany.
Appl Microbiol Biotechnol. 2010 Sep;88(2):485-95. doi: 10.1007/s00253-010-2756-3. Epub 2010 Jul 20.
Sesquiterpenes are particularly interesting as flavorings and fragrances or as pharmaceuticals. Regio- or stereoselective functionalizations of terpenes are one of the main goals of synthetic organic chemistry, which are possible through radical reactions but are not selective enough to introduce the desired chiral alcohol function into those compounds. Cytochrome P450 monooxygenases are versatile biocatalysts and are capable of performing selective oxidations of organic molecules. We were able to demonstrate that CYP109D1 from Sorangium cellulosum So ce56 functions as a biocatalyst for the highly regioselective hydroxylation of norisoprenoids, alpha- and beta-ionone, which are important aroma compounds of floral scents. The substrates alpha- and beta-ionone were regioselectively hydroxylated to 3-hydroxy-alpha-ionone and 4-hydroxy-beta-ionone, respectively, which was confirmed by (1)H NMR and (13)C NMR. The results of docking alpha- and beta-ionone into a homology model of CYP109D1 gave a rational explanation for the regio-selectivity of the hydroxylation. Kinetic studies revealed that alpha- and beta-ionone can be hydroxylated with nearly identical V (max) and K (m) values. This is the first comprehensive investigation of the regioselective hydroxylation of norisoprenoids by CYP109D1.
倍半萜具有作为调味剂和香料或作为药物的特别有趣的性质。萜烯的区域或立体选择性官能化是合成有机化学的主要目标之一，可以通过自由基反应实现，但选择性不够，无法将所需的手性醇官能团引入这些化合物中。细胞色素 P450 单加氧酶是多功能的生物催化剂，能够对有机分子进行选择性氧化。我们能够证明，来自粘细菌 So ce56 的 CYP109D1 可以作为高度区域选择性羟化 norisoprenoids、α-和β-紫罗兰酮的生物催化剂，它们是花香的重要香气化合物。α-和β-紫罗兰酮被区域选择性地羟化为 3-羟基-α-紫罗兰酮和 4-羟基-β-紫罗兰酮，这通过（1）H NMR 和（13）C NMR 得到证实。将α-和β-紫罗兰酮对接入 CYP109D1 的同源模型的结果为羟化的区域选择性提供了合理的解释。动力学研究表明，α-和β-紫罗兰酮可以几乎相同的 V（max）和 K（m）值进行羟化。这是对 CYP109D1 对 norisoprenoids 的区域选择性羟化的首次全面研究。
