一个超氧铁态在一个减少的氧铁血蛋白和模型化合物的超氧铁态
Roman Davydov1, James D Satterlee, Hiroshi Fujii
1Department of Chemistry, Northwestern University, 2156 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Journal of the American Chemical Society
|December 25, 2003
概括
氧的冷还原产生超氧铁 ([FeO2]sup7) 状态,与之前假定的过氧铁 ([FeO2]per7) 形式不同. 这种超氧铁中间体是主要的还原产品,在加热后转化为氧/氧铁态.
科学领域:
- 生物化学 生物化学
- 生物有机化学 生物有机化学
- 频谱学是一种光谱学.
背景情况:
- 许多研究已经将[FeO2]7中心描述为氧铁基 ([FeO2]per7),其中一个铁结合了二离子氧联结体.
- 如果将[FeO2]6母体视为一个超氧铁中心,并将添加的电子定位在O-O部分,那么这种过氧铁态状态可以在启发式上理解.
研究的目的:
- 为了研究各种 oxy-heme 复合物的冷还原产生的 [FeO2]7 中心的特性.
- 为了确定这些减少的氧-海姆中间体的电子结构和自旋密度定位.
- 阐明初级还原产品及其后续的转化.
主要方法:
- 进行了电子磁共振 (EPR) 和电子核双共振 (ENDOR) 实验.
- 在77K的低温降温被用来产生减少的氧-海姆物种.
- 对单体氧血球蛋白 (oxy-GMH3),氧铁性八甲基氨酸和一种血红蛋白模型 (cyclidene) 进行了研究.
主要成果:
- EPR/ENDOR的实验显示,产生的[FeO2]7中心是"超氧铁" ([FeO2]sup7),而不是氧铁.
- 几乎单位的自旋密度被定位在一个超氧子部分上,其端与低自旋铁离子协调.
- [FeO2]sup7物种在150K以上的回火时转化为氧/氧-铁 ([FeO2H]7) 中介物.
结论:
- 氧冷降解的主要降解产物是超氧铁 ([FeO2]sup7) 种.
- 内部氧化还原转换到氧/氧-铁态受环境因素的影响,如H键和质子捐赠.
- 这些发现挑战了以前的表征,并提供了对血红素还原中间体的新理解.
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