二等级的烯循环:结构,机制和工程
Xingming Pan1, Jeffrey D Rudolf2, Liao-Bin Dong1
1State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 211198, China. ldong@cpu.edu.cn.
Natural product reports
|December 18, 2023
概括
第二类烯循环酶 (TCs) 启动复杂的天然产品生物合成. 了解它们的机制是酶工程和创造新 terpenoids 的关键.
科学领域:
- 生物化学 生物化学
- 自然产品生物合成 自然产品生物合成
- 酵素工程是什么意思 酵素工程
背景情况:
- 烯循环酶 (TCs) 是关键的酶,负责合成已知超过95,000种类天然产物.
- 规范性TC根据结构,功能和反应机制被分为两种类型.
- 第二类TC单独调解各种异oprenoid基质的酸启动的循环反应.
研究的目的:
- 审查在自然界中发现的多样化的II类烯环酸.
- 探索它们在重要自然产品如植物激素和真菌美类物质的生物合成中的作用.
- 突出它们在酶工程中的潜力,以发现新型分子.
主要方法:
- 在2023年7月之前对II类TC进行全面的文献审查.
- 对各种II类TC的序列,结构和反应机制的分析.
- 检查结构引导的工程研究.
主要成果:
- 在生物活性化合物的早期生物合成步骤中,II类TC至关重要.
- 这些酶在产生吉伯雷林和真菌美洛特类物质方面起着重要作用.
- 它们的催化机制和生物催化潜力具有重大意义.
结论:
- 对II类TC的彻底理解对于扩大类结构多样性至关重要.
- 工程II类TC为创造新型生物活性分子提供了令人兴奋的前景.
- 对它们机制的进一步研究将推动生物合成和有机化学方面的创新.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
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.
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01:17Pericyclic Reactions: Introduction
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Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
8.3K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.3K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
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01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
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Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
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01:16Cycloaddition Reactions: Overview
2.6K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
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