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氧气激活和电子转移在黄细胞染色体P450 BM3 BM3 中
Tobias W B Ost1, Jonathan Clark, Christopher G Mowat
1School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ. Simon.Daff@ed.ac.uk
Journal of the American Chemical Society
|December 5, 2003
概括
研究人员通过改变Phe393来调整血红降低潜力来修改P450 BM3的黄细胞染色体. 这种旋转状态的转变显著加速了血红素的减少,影响了酶.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 蛋白质工程是指蛋白质工程.
背景情况:
- 基P450 BM3是生物氧化还原反应中的关键酶.
- 在位置393 (Phe393) 的保存型氨酸靠近血红蛋白的活性部位.
- 调节血降低潜力是理解P450 BM3催化机制的关键.
研究的目的:
- 调查Phe393在调节P450 BM3的血降低潜力的作用.
- 阐明改变的还原潜力对酶的催化循环和电子转移步骤的影响.
- 分析P450 BM3突变体中氧铁复合物的稳定性.
主要方法:
- 用局部定向的突变发生法来替代Phe393用Ala,His,Tyr和Trp.
- 进行了动态分析,以确定血红素减少和氧铁复合体衰变的速率.
- 停止流动动力学和可见吸收光谱学被用来研究酶动力学.
主要成果:
- 在Phe393中发生的突变成功调节了的降解潜力,同时保持了结构完整性.
- 在基质结合时的自旋状态转移加速了200倍的缩,而减少电位转移的影响很小.
- 氧铁复合物表现出惊人的稳定性,稳定性与减少潜力正相关.
结论:
- 调节P450 BM3的还原潜力影响了相反方向的电子转移步骤.
- 野生类型酶的降解潜力似乎是针对最大的催化转换率而优化.
- 确定速率的步骤从血减少转移到后来的步骤,如氧铁复合物的减少或突变物中的质子化.
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