Biosynthesis of taxol: enzymatic acetylation of 10-deacetylbaccatin-III to baccatin-III in crude extracts from roots of Taxus baccata.
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.
Zocher
R
R
Institut für Biochemie und Molekulare Biologie, Technische Universität Berlin, Germany. razzo@chem.tu-berlin.de
Weckwerth
W
W
Hacker
C
C
Kammer
B
B
Hornbogen
T
T
Ewald
D
D
D000107:Acetylation; D000470:Alkaloids / Q000096:biosynthesis*; D000972:Antineoplastic Agents, Phytogenic / Q000096:biosynthesis*; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D017239:Paclitaxel / Q000096:biosynthesis*; D018517:Plant Roots / Q000378:metabolism*; D010946:Plants, Medicinal / Q000378:metabolism*; D043823:Taxoids; D014315:Triterpenes / Q000378:metabolism*
D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic; D043823:Taxoids; D014315:Triterpenes; C073950:baccatin III; C042213:10-deacetylbaccatine III; D017239:Paclitaxel