通过非血二铁酶CmlI进行六电子烯氧化的机制
Anna J Komor, Brent S Rivard, Ruixi Fan1
1Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
Journal of the American Chemical Society
|May 21, 2016
概括
氨基醇 (CAM) 生物合成包括由CmlI催化的多步氧化. 一个拟议的催化循环解释了酶如何使用氧和中间体来实现CAM生产的最终六电子氧化.
科学领域:
- 生物化学
- 酵素学
- 有机化学
背景情况:
- 氨基醇 (CAM) 生物合成的高潮是在氨基胺前体 (NH2-CAM) 的六电子氧化到氨基基组.
- 这种反应由非血红二铁氧化酶CmlI催化,在与O2反应时形成过氧中间体 (P).
研究的目的:
- 阐明CAM生物合成中的六电子氧化机制.
- 确定CmlI过氧中间体 (P) 的作用,并确定其他潜在的氧化剂或中间体.
主要方法:
- 在不同的氧同位素条件下使用质谱分析反应产物 ((18) O2和 (16) O2).
- 为了研究NH2-CAM及其中间体的CmlI催化氧化,进行了单次转换反应.
主要成果:
- 质谱测试证实CAM团中的两个氧原子都来自O2.
- 在特定条件下,CAM中存在 (18) O和 (16) O,表明过氧中间体 (P) 的重构.
- 介质NH-OH-CAM被确定为负责CmlI差异性聚合物的减少剂.
结论:
- 一个催化循环被提出,其中NH2-CAM被氧化为NH-OH-CAM,然后再减少CmlI,允许P重构.
- 然后,改造后的P将NH-OH-CAM氧化为NO-CAM,然后再氧化为CAM,并加入第二个O2原子.
- 完全的六电子氧化发生在活性位点内,只需要两个外源电子.
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