动态同位素效应涉及两个电友性氧化剂在细胞染色体p450催化氧化中
Martin Newcomb1, David Aebisher, Runnan Shen
1Department of Chemistry, University of Illinois at Chicago, 60607, USA. men@uic.edu
Journal of the American Chemical Society
|June 6, 2003
概括
在研究P450 (P450) 酶时,这项研究使用了动态同位素效应来揭示多个基化途径. 这些发现支持"两氧化剂"模型,而不是P450催化剂的"两状态"模型.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 有机化学 有机化学
背景情况:
- 细胞P450酶催化了关键的氧化反应.
- 了解P450催化酸化的精确机制是复杂的.
- 动态同位素效应 (KIE) 是探测反应机制的宝贵工具.
研究的目的:
- 为了研究转基因-2-phenylcyclopropylmethane的细胞染色体P450催化氧化酶的分子内KIEs.
- 区分P450基化所提出的机制模型,特别是"两氧化剂"和"两态"模型.
主要方法:
- 通过使用甲基二化转基-2-cyclopropylmethane-d2.d2.的分子内KIEs的确定.
- 从与各种P450酶 (CYP2B1,CYPDelta2E1,CYPDelta2E1 T303A) 的反应中产生的产品比率的分析 (trans-2-phenylcyclopropylmethanol和1-phenyl-3-buten-1-ol).
- 较量KIE和产品比率的脱和非脱基板.
主要成果:
- 显而易见的分子内KIEs因不同的产品和酶基质组合而异.
- 两种观察到的产品的比率 (2/3) 随着三二甲基的替代而下降,这表明了显著的C-H键裂变同位素效应.
- 观察到的KIEs和产品分布与"两个状态"模型不一致,但与"两个氧化剂"模型保持一致.
结论:
- 这些结果要求P450催化氧化有多个途径.
- 这些发现强烈支持"两氧化剂"模型,在氧化过程中涉及氧铁和铁氧氧物种.
- 这项研究提供了对细胞染色体P450酶复杂反应性的关键机理见解.
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