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相关概念视频

Thermal Sigmatropic Reactions: Overview01:16

Thermal Sigmatropic Reactions: Overview

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Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in...
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Valence Bond Theory02:45

Valence Bond Theory

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Overview of Valence Bond Theory
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Valence Bond Theory and Hybridized Orbitals02:38

Valence Bond Theory and Hybridized Orbitals

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According to valence bond theory, a covalent bond results when: (1) an orbital on one atom overlaps an orbital on a second atom, and (2) the single electrons in each orbital combine to form an electron pair. The strength of a covalent bond depends on the extent of overlap of the orbitals involved. Maximum overlap is possible when the orbitals overlap on a direct line between the two nuclei.
A σ bond (single bond in a Lewis structure) is a covalent bond in which the electron density is...
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Singularity Functions for Shear01:26

Singularity Functions for Shear

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In structural analysis, singularity functions are crucial in simplifying the representation of shear forces in beams under discontinuous loading. These functions describe discontinuous  variations in shear force across a beam with varying loads by using a single mathematical expression, regardless of the complexity of the loading conditions. The singularity functions are derived from creating a free-body diagram of the beam and then making conceptual cuts at specific points to examine the...
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Molecular Orbital Theory I02:35

Molecular Orbital Theory I

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MO Theory and Covalent Bonding02:40

MO Theory and Covalent Bonding

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The molecular orbital theory describes the distribution of electrons in molecules in a manner similar to the distribution of electrons in atomic orbitals. The region of space in which a valence electron in a molecule is likely to be found is called a molecular orbital. Mathematically, the linear combination of atomic orbitals (LCAO) generates molecular orbitals. Combinations of in-phase atomic orbital wave functions result in regions with a high probability of electron density, while...
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Involvement of a creBC-anmK-L1/L2 regulatory circuit in β-lactamase expression and β-lactam resistance of Stenotrophomonas maltophilia.

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相关实验视频

Updated: Jul 27, 2025

Sigma's Non-specific Protease Activity Assay - Casein as a Substrate
11:37

Sigma's Non-specific Protease Activity Assay - Casein as a Substrate

Published on: September 17, 2008

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这对 σ 的含义.

Ren-Hsuan Ku1, Li-Hua Li2,3, Yi-Fu Liu1

  • 1Department of Biotechnology and Laboratory Science in Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.

Microbiology spectrum
|June 7, 2023
PubMed
概括
此摘要是机器生成的。

失去了斯坦诺罗霍蒙纳斯 (Stenotrophomonas maltophilia) 的存在.

关键词:
这就是OmpaA.RpoN RpoN 是一个字符串.外膜蛋白质的外膜蛋白质.西格玛因子 (sigma factor) 是一个因子.

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相关实验视频

Last Updated: Jul 27, 2025

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科学领域:

  • 细菌外膜蛋白质的结构和功能
  • 微生物应激反应机制的微生物应激反应机制
  • 在细菌中进行基因组和转录组分析.

背景情况:

  • 外膜蛋白A (OmpA) 对于细菌细胞外的完整性至关重要.
  • 一种缺乏OmpA C终端域的Stenotrophomonas maltophilia突变 (KJΔOmpA299-356) 显示了对氧化应激的耐受性降低.
  • 这种降低耐受性背后的确切机制尚未完全阐明.

研究的目的:

  • 为了研究基底的分子机制降低梅纳介导氧化应激耐受性在Stenotrophomonas maltophilia KJΔOmpA299-356突变.
  • 为了确定关键的基因和参与压力反应路径中涉及的调节因素,受OmpA C-终端域损失的影响.
  • 阐明连接OmpA功能,σ因子活性和氧化应激耐受性的调节电路.

主要方法:

  • 野生类型和KJΔOmpA299-356 Stenotrophomonas maltophilia菌株的比较转录组分析.
  • 基因补充试验验证特定基因 (例如, ompO) 在应激耐受性中的作用.
  • 对响应OmpA突变的σ因子表达水平 (rpoN,rpoP,rpoE) 的分析.
  • 构建和描述突变菌株的单个 σ 因子,以评估它们对应力耐受性的贡献.

主要成果:

  • 在KJΔOmpA299-356突变体中,OmpO基因被显著降低调节,其补充恢复了男素耐受性.
  • 三个σ因子的表达,rpoN (下调),rpoP (上调) 和rpoE (上调),在突变者中发生了变化.
  • 确定rpoN的下调和rpoE的上调是减少氧化应激耐受性的关键贡献者.
  • OmpA C终端域的损失触发了外应激反应,导致 σE 激活,这反过来减少了 rpoN 和 ompO 表达.

结论:

  • OmpA C-终端域对于在Stenotrophomonas maltophilia中维持氧化应激耐受性至关重要.
  • 一个涉及ΔompA299-356突变体,rpoE和ompO的调节电路调节了氧化应激耐受性的变化.
  • 在观察到的应激反应表型中,rpoE和rpoN之间的交叉调节起着重要作用.
  • OmpA与糖层的相互作用对于包膜完整性和细菌应激耐受性至关重要.