Stereochemistry of eudesmane cation formation during catalysis by aristolochene synthase from Penicillium roqueforti
作者:David J. Miller、Jiali Gao、Donald G. Truhlar、Neil J. Young、Veronica Gonzalez、Rudolf K. Allemann
DOI:10.1039/b804198a
日期:——
D(2)O. The results reveal proton loss from C12 during the reaction and incorporation of another proton from the solvent. Incubation of with PR-AS in D(2)O led to the production of (6R)-[6-(2)H] aristolochene, indicating that protonation occurs from the face of the 10-membered germacrene ring opposite the isopropylidene group. Hence these results firmly exclude proton transfer from C12 to C6 of germacryl
据推测,马兜铃酸合酶催化的法呢基二磷酸环化反应(1)通过(S)-germacrene A(3)进行。但是,迄今为止,证明该中性中间体质子化的活性位点酸很难鉴定,并且基于高水平的从头算分子轨道和密度泛函理论计算,最近提出了质子转移机制,其中质子从C12的C12转移。细菌丙烯酸阳离子与细菌丙烯酸阳离子(2)的C6,C7-双键直接或通过紧密结合的水分子进行。在这项工作中,通过分析1和[12,12,12,13,13,13-(2)H(6)]-法呢基二磷酸酯(15)与马氏青霉素合酶从罗氏青霉(PR-AS)在H(2)O和D(2)O中的合成。结果表明,在反应过程中C12失去了质子,并从溶剂中引入了另一个质子。PR-AS在D(2)O中的孵育导致(6R)-[6-(2)H]马兜铃的产生,表明质子化是从与异亚丙基相反的10元胚芽环的表面发生的。因此,这些结果完全排除了质子丙烯酸阳离子从C12到C6的质子转移。我们在这里提出Lys