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基质的扭曲有助于丁5'-单酸脱碳酶的催化
Masahiro Fujihashi1, Toyokazu Ishida, Shingo Kuroda
1Department of Chemistry, Graduate School of Science, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|October 25, 2013
概括
奥罗提丁5'-单酸脱碳酶 (ODCase) 加速一个关键反应超过1017倍. 新的晶体结构揭示了ODCase如何使用基质扭曲和过渡状态稳定来催化丁5'-单酸盐 (OMP) 脱碳化.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 结构生物学 结构生物学
背景情况:
- 五胺单酸脱碳酶 (ODCase) 催化了五胺单酸 (OMP) 到五胺单酸 (UMP) 的基本脱碳化.
- ODCase的精确反应机制仍然是争论的主题,特别是关于基质扭曲和过渡状态稳定作用.
研究的目的:
- 阐明奥罗提丁5-单酸脱碳酶 (ODCase) 的有争议的反应机制.
- 调查基质扭曲和过渡状态稳定在ODCase催化中的贡献.
主要方法:
- 获取和分析八个新的晶体结构的ODCase复合体与连接体类似物.
- 计算分析,包括分子动力学和量子力学/分子力学 (QM/MM) 方法,酶基质中间体和电子能量.
- 检查酶活性部位内的联结体诱导的结构变化.
主要成果:
- 晶体结构揭示了ODCase活性部位内对联体类似物 (如6-甲基-UMP,OMP Ester) 的显著扭曲.
- 计算研究表明,在酶基质复合体中,碳酸盐组与金胺环之间的键被扭曲.
- 发现这种扭曲会使激活自由能量 (ΔΔG()) 降低10-15%.
结论:
- ODCase采用了一种双重策略,涉及基质扭曲和催化过渡状态稳定.
- 通过稳定过渡状态,酶的催化效率得到了显著提高,其中素72 (K72) 起着主要的作用.
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