使用单个残留开关的二二烯合成酶反应的复杂性越来越高
Dana Morrone1, Meimei Xu, D Bruce Fulton
1Iowa State University, Department of Biochemistry, Biophysics, and Molecular Biology, Ames, Iowa 50011, USA.
Journal of the American Chemical Society
|March 28, 2008
概括
在合成酶酶中改变单一的氨基酸会大大改变它们的反应复杂性. 这项研究揭示了特定的残留物替代如何改变产品结果,影响类天然产品的多样性.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 自然产品 化学 化学
背景情况:
- 合成酶 (TPS) 是产生各种类天然产品的关键酶.
- 这些酶通过碳基化中间体催化复杂反应,定义生物合成途径.
- 了解TPS产品的特异性是他们研究的关键.
研究的目的:
- 研究如何改变合成酶中的活性部位残留物影响反应复杂性和产品结果.
- 探索特定氨基酸替代在调节TPS催化通路中的作用.
主要方法:
- 一个本地皮马拉丁合成酶的局部定向突变发生.
- 对改变的酶活性和由此产生的烯产物的分析.
- 来自野生类型和突变酶的产品概况的比较.
主要成果:
- 在关键位置用异黄素 (Ile) 取代三素 (Thr) 极大地增加了反应的复杂性.
- 该产品从三环皮马拉迪因转变为重新排列的四环,阿菲迪科尔-15-.
- 这个单一的残留物作为一个开关,证明了酶的可塑性.
结论:
- 活性部位残留物的性质决定了合成酶产品的临界结果.
- 亚利法性残留物替代可以使更复杂的反应成为可能,突出显示了基质构成的重要性.
- 合成酶的可塑性支持自然产品代谢中的多样性导向假设.
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.
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...
[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.
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.
[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: Characteristics of Dienophiles
In a Diels–Alder reaction, the diene is usually an electron-rich system and acts as a nucleophile, whereas the dienophile is electron-deficient and functions as an electrophile. Much like the diene, the nature of the dienophile significantly impacts the outcome of the reaction.
Characteristics of Dienophiles
Generally, the best dienophiles are alkenes containing electron-withdrawing substituents such as carbonyl, nitrile, and nitro groups. The feasibility of a Diels–Alder reaction depends on...
Characteristics of Dienophiles
Generally, the best dienophiles are alkenes containing electron-withdrawing substituents such as carbonyl, nitrile, and nitro groups. The feasibility of a Diels–Alder reaction depends on...


