氧化合成酶的基质和异型特定的二氧化复合物
David Li1, Mariam Kabir, Dennis J Stuehr
1Department of Physiology and Biophysics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.
Journal of the American Chemical Society
|May 10, 2007
概括
基质与氧化合成酶 (NOS) 的结合影响了氧-氧结合. 来自L-氨酸的键促进了NO的形成,而N--L-氨酸的结合则没有,这揭示了NOS催化过程中的机制差异.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 频谱学是一种光谱学.
背景情况:
- 氧化合成酶 (NOS) 通过两步反应产生氧化 (NO).
- 第一个步骤将L-氨酸 (Arg) 转化为N--L-氨酸 (NOHA),第二个步骤将NOHA转化为氨酸和NO.
- 了解这些步骤之间的机制差异对于酶功能至关重要.
研究的目的:
- 调查NOS的两个催化步骤中的机械差异.
- 研究可诱导的NOS氧化酶域 (iNOSoxy) 的二氧化物结合复合物的结构性质.
主要方法:
- 共振拉曼光谱法. 共振拉曼光谱法.
- 一个自制的连续流速快速溶液混合机.
- 研究了无基质和与基质结合的INOSoxy复合物.
主要成果:
- 在无基质的iNOSoxy中确定了1133cm-1的OO拉伸频率.
- 观察到L-氨酸结合时的转移到1126cm-1,表明H-结合与铁结合的二氧化物.
- 在NOHA结合时没有观察到O-O频率的变化,这表明缺乏直接的H-结合.
结论:
- 基质特定的结相互作用对NOS催化非常重要.
- 来自L-氨酸的H键促进了O-O键裂变以形成NO.
- 在NOHA结合过程中缺少H键,可以防止过早的O-O键裂变,从而允许核友性添加.
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