重原子同位素对来自Bacillus subtilis的氧酸盐脱碳酶催化反应的影响
Laurie A Reinhardt1, Drazenka Svedruzic, Christopher H Chang
1Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Journal of the American Chemical Society
|January 30, 2003
概括
氧沙酸脱碳酶 (OxDC) 使用和二氧化碳来切割氧沙酸,产生酸盐和二氧化碳. 动态同位素效应表明了涉及氧沙酸盐和甲酸盐中间体的激进机制.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 化学动力学 化学动力学
背景情况:
- 氧沙酸脱碳酶 (OxDC) 催化氧沙酸分裂成二氧化碳和甲酸盐.
- 来自Aspergillus niger和Bacillus subtilis的酶含有Mn (II) 并且需要氧气.
- 一个自由基的机制已经提出,但没有最终证明.
研究的目的:
- 用重原子动态同位素效应研究细菌OxDC的催化机制.
- 提供实验证据支持或反对激进的中间途径.
主要方法:
- 重原子动态同位素效应测量是在重组Bacillus subtilis OxDC.上进行的.
- 用同位素标记的酸盐用于在不同的pH值下测量 (13) C和 (18) O同位素的影响.
- 对正常同位素和逆同位素效应进行分析,以阐明反应步骤.
主要成果:
- 在pH值4.2和5.7.7时,观察到酸盐和二氧化碳生产的正常 (13) C同位素效应.
- 在两种pH值下观察到正常的 (18) O同位素效应来形成甲酸盐.
- 在pH值5.7的CO2形成中观察到一个反向的 (18) O同位素效应.
结论:
- 观察到的动态同位素效应支持涉及激素中间体的多步机制.
- 一个质子-合电子转移产生一个氧酸盐基,其次是去碳氧化到一个形式基.
- 随后的减少和质子化产生最终的成型产品.
相关概念视频
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