Subunit composition of hinokiresinol synthase controls enantiomeric selectivity in hinokiresinol formation
作者:Masaomi Yamamura、Shiro Suzuki、Takefumi Hattori、Toshiaki Umezawa
DOI:10.1039/b918656e
日期:——
Asparagus officinalis hinokiresinol synthase (HRS) is composed of two subunits, HRSα and HRSβ. Individually, each subunit forms (E)-hinokiresinol (EHR) from 4-coumaryl 4-coumarate, whereas a mixture of both subunits forms (Z)-hinokiresinol (ZHR) from the same substrate. In this study, we analyzed the enantiomeric compositions of ZHR and EHR formed after incubation of 4-coumaryl 4-coumarate with recombinant subunit proteins, recHRSα and/or recHRSβ, and with naturally occurring A. officinalis ZHR. The enantiomeric composition of ZHR formed by the mixture of recHRSα and recHRSβ was (+)-100% enantiomer excess (e.e.), identical to that of A. officinalis ZHR. In contrast, the enantiomeric compositions of EHR formed by recHRSα and recHRSβ, individually, were (−)-20.6 and (−)-9.0% e.e., respectively. These results clearly demonstrate that the subunit composition of A. officinalis HRS controls not only cis/trans isomerism but also enantioselectivity in hinokiresinol formation.
天门冬桧醚合成酶(HRS)由 HRSα 和 HRSβ 两个亚基组成。每个亚基单独从 4-香豆酰 4-香豆酸酯中生成(E)-桧烯二酚(EHR),而两个亚基的混合物则从相同的底物中生成(Z)-桧烯二酚(ZHR)。在本研究中,我们分析了 4-香豆素与重组亚基蛋白 recHRSα 和/或 recHRSβ 以及天然 A. officinalis ZHR 培养后形成的 ZHR 和 EHR 的对映体组成。由 recHRSα 和 recHRSβ 混合物形成的 ZHR 对映体组成为对映体过量 (+)-100% (e.e.),与 A. officinalis ZHR 的对映体组成相同。相比之下,recHRSα 和 recHRSβ 分别形成的 EHR 对映体组成分别为 (-)-20.6% 和 (-)-9.0% e.e.。这些结果清楚地表明,A. officinalis HRS 的亚基组成不仅控制着顺式/反式异构体,还控制着桧脂醇形成过程中的对映体选择性。