Cho Man-Ho, Moinuddin Syed G A, Helms Gregory L, Hishiyama Shojiro, Eichinger Dietmar, Davin Laurence B, Lewis Norman G
Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
Proc Natl Acad Sci U S A. 2003 Sep 16;100(19):10641-6. doi: 10.1073/pnas.1934562100. Epub 2003 Sep 5.
An enantio-specific polyphenol oxidase (PPO) was purified approximately 1,700-fold to apparent homogeneity from the creosote bush (Larrea tridentata), and its encoding gene was cloned. The posttranslationally processed PPO ( approximately 43 kDa) has a central role in the biosynthesis of the creosote bush 8-8' linked lignans, whose representatives, such as nordihydroguaiaretic acid and its congeners, have potent antiviral, anticancer, and antioxidant properties. The PPO primarily engenders the enantio-specific conversion of (+)-larreatricin into (+)-3'-hydroxylarreatricin, with the regiochemistry of catalysis being unambiguously established by different NMR spectroscopic analyses; the corresponding (-)-enantiomer did not serve as a substrate. This enantio-specificity for a PPO, a representative of a widespread class of enzymes, provides additional insight into their actual physiological roles that hitherto have been difficult to determine.
从石炭酸灌木（Larrea tridentata）中纯化出一种对映体特异性多酚氧化酶（PPO），纯化倍数约为1700倍，达到了表观均一性，并克隆了其编码基因。翻译后加工的PPO（约43 kDa）在石炭酸灌木8-8'连接木脂素的生物合成中起核心作用，其代表物如去甲二氢愈创木酸及其同系物具有强大的抗病毒、抗癌和抗氧化特性。PPO主要促使（+）-拉瑞三素对映体特异性转化为（+）-3'-羟基拉瑞三素，不同的核磁共振光谱分析明确确定了催化的区域化学；相应的（-）-对映体不作为底物。这种对PPO（一种广泛存在的酶类的代表）的对映体特异性，为迄今难以确定的其实际生理作用提供了更多见解。
