通过素合成酶 (FtmOx1) 在内氧化物安装过程中提供气,但不通过素 (Y68) 提取
Journal of the American Chemical Society
|May 24, 2019
概括
氧酶FtmOx1使用直接的原子转移 (HAT) 来进行白原体内氧化. 一个关键的氨酸残留物,Y68,作为最后一步的供体,挑战了以前的模型.
科学领域:
- 生物化学
- 酵素学
- 有机化学
背景情况:
- 在酶反应中,从碳转移到铁中的原子转移 (HAT) 是至关重要的.
- 防止氧气反弹对于除化以外的反应至关重要.
- 之前认为FtmOx1是一种真菌氧酶,可以将Tyr 224作为verruculogen生物合成中的HAT中间体.
研究的目的:
- 重新研究FtmOx1催化原体内氧化的机制.
- 为了确定最终的原子转移阶段所涉及的特定氨酸残留物.
- 提出一个对酶基质复合体对接的修订模型.
主要方法:
- 针对FtmOx1的基因突变,用氨酸替代候选氨酸残留物.
- 在不同氧度下分析反应产物.
- 对基质中间体进行光谱监测.
主要成果:
- 从C21到费里尔中间体的直接HAT发生,具有竞争性氧气反弹.
- 低氧度有利于氧化,而高度则有利于内氧化.
- 突变基因鉴定出Tyr 68是C26基的重要 donor,而不是Tyr 224.
结论:
- 该机制涉及C21的直接HAT,并在最后一步确定Tyr 68为关键的H原子供体.
- 一个新的对接模型将C21放在铁辅因子附近,C26在Tyr68附近.
- 亚酸盐可以抑制短暂的铁基,而不会抑制酶循环.
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