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相关概念视频

Enzymes02:34

Enzymes

Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Enzymes and Activation Energy01:13

Enzymes and Activation Energy

The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H01:13

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H

All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for the...
Enzymes and Activation Energy01:13

Enzymes and Activation Energy

The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...

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A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments
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A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments

Published on: October 2, 2012

合成,结构和活动的增强启动器为氨酸转化酶.

Jennifer A Love1, Melanie S Sanford, Michael W Day

  • 1Arnold and Mabel Beckman Laboratories for Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.

Journal of the American Chemical Society
|August 14, 2003
PubMed
概括

催化剂与不同的素连接体加快了烯基甲解反应. 从这些催化剂中更快地分离素,可以提高环开转化聚合和环闭转化的启动率.

科学领域:

  • 有机金属化学 有机金属化学
  • 催化剂是一种催化剂.
  • 聚合物科学 聚合物科学

背景情况:

  • 基于的催化剂对于烯转化反应至关重要.
  • 结构和连接体环境显著影响催化剂活性.
  • 了解启动机制是优化催化性能的关键.

研究的目的:

  • 为了合成和描述新型的烯甲基解剖催化剂.
  • 为了研究素连接体对催化剂启动和活性的影响.
  • 为了将氨酸解离率与ROMP和RCM中的反应动力学相关联.

主要方法:

  • 有一般结构的鲁复合物的合成 (H(2) IMes) ((PR(3)) ((Cl) ((2) Ru=CHPh.
  • 测量氨酸解离速率常数的动力学研究 (k(1)).
  • 在环开转化聚合 (ROMP) 和环闭转化 (RCM) 中催化剂性能的评估.

主要成果:

  • 催化剂制备涉及从商业上可用的前体进行两步合成.
  • 随着氨酸供体强度的下降,氨酸解离率会增加.
  • 与PCy(3) 类似物相比,含有三基啡的复合物显示出明显改善的启动.
  • 氨酸再关联率与氨酸电子产品没有直接关联.

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Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
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  • 较快的氨酸解离通常会导致加速的氨酸转化反应速率.
  • 结论:

    • 催化剂的设计可以通过修改素连接物来调整,以控制启动速率.
    • 优化氨酸解离对于提高催化转化反应的效率至关重要.
    • 这些发现对有机合成和聚合物化学都有影响.