Zocher R, Weckwerth W, Hacker C, Kammer B, Hornbogen T, Ewald D
Institut für Biochemie und Molekulare Biologie, Technische Universität Berlin, Germany.
Biochem Biophys Res Commun. 1996 Dec 4;229(1):16-20. doi: 10.1006/bbrc.1996.1751.
The biosynthesis of taxol is a multistep process. One intermediate reaction is the acetylation of 10-deacetylbaccatin-III (10-DAB) to baccatin-III, an assumed precursor of taxol. Here we describe the cell free acetylation of 10-DAB in crude extracts from roots of Taxus baccata saplings using 14C-or 3H-labeled acetyl-coenzyme A as the acetyl donor. The reaction is strictly dependent on the addition of 10-DAB and is specific for the 10-hydroxyl group of the taxane ring. Formation of radiolabeled baccatin-III was confirmed by co-chromatography of the labeled product with authentic baccatin-III in different TLC-systems and HPLC. Furthermore, the acetylation product showed an identical UV spectrum as authentic baccatin-III. Crude extracts from cambium of stems yielded three- to fivefold lower activity. This is in agreement with our finding that the taxol titer in roots was considerably higher than that in cambium.
紫杉醇的生物合成是一个多步骤过程。其中一个中间反应是将10 - 去乙酰巴卡亭III（10 - DAB）乙酰化为巴卡亭III，巴卡亭III被认为是紫杉醇的前体。在此，我们描述了以14C或3H标记的乙酰辅酶A作为乙酰供体，在欧洲红豆杉幼苗根的粗提物中进行10 - DAB的无细胞乙酰化反应。该反应严格依赖于10 - DAB的添加，并且对紫杉烷环的10 - 羟基具有特异性。通过在不同的薄层色谱（TLC）系统和高效液相色谱（HPLC）中，将标记产物与 authentic baccatin - III进行共色谱分析，证实了放射性标记的巴卡亭III的形成。此外，乙酰化产物显示出与 authentic baccatin - III相同的紫外光谱。茎形成层的粗提物活性低三到五倍。这与我们的发现一致，即根中的紫杉醇含量显著高于形成层中的含量。
