一种用于 (+) -δ-卡丁烯合成酶的1,6环闭合机制
Juan A Faraldos1, David J Miller, Verónica González
1School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom.
Journal of the American Chemical Society
|March 9, 2012
概括
树的 (+) -δ-卡丁烯合成酶 (DCS) 显示了机械的多功能性,可能利用1,6和1,10循环路来产生二. 这项研究使用了机械探头来研究DCS的催化机制.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 有机化学 有机化学
背景情况:
- 来自Gossypium arboreum的重组 (+) -δ-cadinene合成酶 (DCS) 合成 δ-cadinene,这是棉花植物的前体.
- DCS在将法尼西二酸盐 (FDP) 转化为δ-丁烯时表现出高保真度,留下最小的机械痕迹.
- 提出的δ-cadinene形成的机制包括通过 (3R) - 尼罗利二酸盐 (NDP) 或避免NDP的替代途径进行1,10-循环,以及通过bisabolyl离子进行1,6环闭合.
研究的目的:
- 为了研究来自Gossypium arboreum的重组 (+) -δ-cadinene合成酶 (DCS) 的催化机制.
- 阐明涉及Farnesyl diphosphate (FDP) 到 δ-cadinene 的循环转化过程中的机械路径.
- 使用机械探测器探索1,6和1,10循环化途径的潜在参与.
主要方法:
- 使用各种机械探针,包括化和化法二酸盐 (FDP) 类似物.
- 用修改的FDP基板化DCS并分析得到的基产品.
- 使用化FDP类似物 (2F-FDP,10F-FDP,6F-FDP) 和其他FDP衍生物 ((2Z,6E) -FDP,二,6,7-二-FDP,NDP) 来探测循环机制.
主要成果:
- 化FDP类似物在C2和C10处作为抑制剂,产生2F-germacrenes和10F-humulene,支持1,10和1,11循环.
- 用6F-FPP, (2Z,6E) -FDP,内二酸盐和NDP进行的化表明1,6环闭路的参与,由bisabolyl和terpinyl离子中间体表明.
- 乳标记 ([1-(2) H(1) ](1R) -FDP) 证实了通过 (3R) -NDP的1,6路径,与之前的发现相一致,并解释了卡迪尼尼尔六二烯的cis立体化学.
结论:
- DCS表现出机械的多功能性,能够使用多个循环路 (1,6-和1,10-).
- 这项研究强调了在基烯形成中的替代生物合成路径的潜力.
- 虽然没有明确偏好某一途径,但这些发现为DCS.的复杂催化机制提供了洞察力.
相关概念视频
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Diels–Alder Reaction: Characteristics of Dienes
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...


