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相关概念视频

Cationic Chain-Growth Polymerization: Mechanism00:57

Cationic Chain-Growth Polymerization: Mechanism

The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
Ziegler–Natta Chain-Growth Polymerization: Overview01:17

Ziegler–Natta Chain-Growth Polymerization: Overview

Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
Anionic Chain-Growth Polymerization: Mechanism01:04

Anionic Chain-Growth Polymerization: Mechanism

The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael acceptor.
Radical Chain-Growth Polymerization: Mechanism01:09

Radical Chain-Growth Polymerization: Mechanism

The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this species into the...
Peptidoglycan Synthesis01:28

Peptidoglycan Synthesis

Structure of PeptidoglycanPeptidoglycan is a vital structural component of the bacterial cell wall, providing mechanical strength and shape to the cell. It consists of repeating units of two sugars—N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)—linked by β-1,4 glycosidic bonds. These sugar chains are cross-linked by short peptide chains, forming a mesh-like polymer that surrounds the bacterial plasma membrane.Cytoplasmic Phase – Precursor SynthesisPeptidoglycan biosynthesis begins in...
Radical Chain-Growth Polymerization: Overview01:10

Radical Chain-Growth Polymerization: Overview

Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...

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相关实验视频

Updated: Jul 10, 2026

From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028
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From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028

Published on: January 13, 2017

类似于GNAT的策略用于多基基链启动.

Liangcai Gu1, Todd W Geders, Bo Wang

  • 1Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.

Science (New York, N.Y.)
|November 10, 2007
PubMed
概括

研究人员发现了一种新的生物化学途径,用于在curacin A.中启动多基胺合成. 一个独特的与GCN5相关的N-乙转移酶域执行双重功能,使抗癌化合物库拉A的产生成为可能.

科学领域:

  • 生物化学 生物化学
  • 分子生物学分子生物学
  • 自然产品的合成自然产品的合成

背景情况:

  • 库拉A是一种来自Lyngbya majuscula的抗癌剂,其生物合成依赖于多基合成酶 (PKS).
  • 在此之前,PKS加载模块的链启动机制是未知的.

研究的目的:

  • 阐明在curacin A PKS中聚基酸链启动的生物化学策略.
  • 描述库拉A装载模块内的新型酶活性.

主要方法:

  • 生物化学测试以评估CurA加载三域的酶活性.
  • 进行X射线晶体学以确定GNAT (L) 域的结构.
  • 现场定向突变发生和计算建模,以调查关键残留物.

主要成果:

  • 一个与GCN5相关的N-乙转移酶 (GNAT) 域 (GNAT(L)) 呈现出前所未有的双功能脱碳酶/S-乙转移酶活性.
  • GNAT(L) 催化马洛尼尔-协酶A的脱碳化到乙-CoA,然后将S-乙转移到一种乙载体蛋白 (ACP(L)).
  • 晶体结构显示出明显的基质道,而突变发生识别出了关键残留物 (His389,Thr355),这些残留物参与了脱碳化.

结论:

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Last Updated: Jul 10, 2026

From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028
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From a Natural Product to Its Biosynthetic Gene Cluster: A Demonstration Using Polyketomycin from Streptomyces diastatochromogenes Tü6028

Published on: January 13, 2017

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly
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Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

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Monitoring GPCR-β-arrestin1/2 Interactions in Real Time Living Systems to Accelerate Drug Discovery

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  • 库拉A加载模块使用一个独特的GNAT域来启动链.
  • 马洛尼尔-CoA的脱碳化在乙基转移之前,产生了乙-ACP (L) 起始单元.
  • 这一发现揭示了GNAT超级家族中用于聚基化物合成的新生化学策略.