Stereochemistry of the Macrocyclization and Elimination Steps in Taxadiene Biosynthesis through Deuterium Labeling
作者:Qingwu Jin、David C. Williams、Mehri Hezari、Rodney Croteau、Robert M. Coates
DOI:10.1021/jo0502091
日期:2005.6.1
synthase catalyzes the cyclization of (E,E,E)-geranylgeranyl diphosphate (GGPP) to taxa-4(5),11(12)-diene (Scheme 1, 5 → 2) as the first committed step of Taxol biosynthesis. Deuterated GGPPs labeled stereospecifically at C-1, C-4, and C-16 were synthesized and incubated with recombinant taxadiene synthase from Taxus brevifolia to elucidate the stereochemistry of the cyclization reaction at these positions
紫杉二烯合酶催化将(E,E,E)-香叶基香叶基二磷酸(GGPP)环化为紫杉4(5),11(12)-二烯(方案1,5 → 2),这是紫杉醇生物合成的第一步。合成了在C-1,C-4和C-16立体标记的氘代GGPP,并与来自短叶红豆杉的重组紫杉二烯合酶一起孵育,以阐明这些位置上环化反应的立体化学。从(获得的氘标记taxadienes - [R [1- - )2 ħ 1 ] - ,(小号) - 〔1- 2 ħ 1 ] - ,和[16,16,16- 2ħ 3 ] GGPPS(9,10,和23B)被建立为具有在2α氘和2βCH 2点16CH 3的位置,分别由高场1 H NMR光谱(等式1-3)。(R)-[4- 2 H 1 ] GGPP(17)与重组酶的温育得到[5β- 2 H 1 ] taxa-3(4),11(12)-二烯的10:10:80混合物,[5β- 2 H 1根据产物的GC / MS分析(eq