用水辅助的氧化机制用于血代谢
Takashi Kamachi1, Kazunari Yoshizawa
1Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 812-8581, Japan.
Journal of the American Chemical Society
|July 28, 2005
概括
血红素氧酶 (HO) 使用水辅助的氧机制进行血红素代谢. 计算研究表明,桥梁水分子显著降低了血红素氧化激活屏障,从而实现了高效的酶活性.
科学领域:
- 生物化学 生物化学
- 计算化学的计算化学
- 酶学 是一种酶学.
背景情况:
- 血红素氧酶 (HO) 对于血红素代谢至关重要.
- 以前的研究表明,铁-氧物种缺乏足够的氧化能力来进行血氧化.
- 了解HO介导的血氧化过程的精确机制至关重要.
研究的目的:
- 通过使用计算方法,通过血氧酶 (HO) 调查血红素代谢的机制.
- 阐明铁氧物种和蛋白质环境在血氧化中的作用.
- 为HO催化氧化提出详细的机制.
主要方法:
- 使用B3LYP密度函数理论计算.
- 模型包括完整的原氨酸IX和氨酸系统.
- 量子力学/分子力学 (QM/MM) 计算用于整个酶模型.
主要成果:
- 铁-氧物种被证实不足以进行血氧化.
- 由于氨酸的扭曲,直接的氧攻击机制具有很高的激活屏障 (49.8 kcal/mol).
- 一个桥梁水分子通过最大限度地减少氨酸扭曲,使激活屏障大幅降低到13.9kcal/mol.
- 使用全酶模型进行的QM/MM计算证实了水分子在蛋白质环境中的重要性.
结论:
- 建议使用水辅助的氧化机制来通过血氧酶氧化血.
- 蛋白质环境,特别是一个关键的水分子,对于促进低屏障和区域选择性血氧化至关重要.
- 计算研究为血液氧化酶的酶机制提供了重要的见解.
相关概念视频
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Oxymercuration–reduction of alkenes is one of the major reactions converting alkenes to alcohols. It involves the hydration of alkenes with mercuric acetate in a mixture of tetrahydrofuran and water, forming an organomercury adduct. This is followed by a demercuration step in which the adduct is reduced to an alcohol using sodium borohydride.
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Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
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The process of oxidation in a chemical reaction is observed in any of the three forms:
The process of oxidation in a chemical reaction is observed in any of the three forms:
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Radical Autoxidation
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...


