EPR和红外光谱证据表明,当乙-共酶A合成酶与CO反应时,会形成一种动力学上有能力的磁性中间体
Simon J George1, Javier Seravalli, Stephen W Ragsdale
1Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|September 30, 2005
概括
一氧化碳脱酶/乙-CoA合成酶 (CODH/ACS) 对于自生长至关重要. 这项研究确定了NiFeC物种是ACS与一氧化碳 (CO) 反应时的主要形式.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 生物有机化学 生物有机化学
背景情况:
- 一氧化碳脱酶/乙-CoA合成酶 (CODH/ACS) 通过伍德-卢恩达尔通路促进微生物的自营生长.
- 碳化合物被引导到乙-甲酸合成酶 (ACS) 活性部位,用于乙-甲酸合成.
- 该ACS活性位点有一个 [4Fe-4S] 集群和一个双核中心 (近端和远端Ni位点).
研究的目的:
- 来自C.hydrogenoformans*的单体ACS的碳化形式的特征.
- 阐明与一氧化碳 (CO) 反应时形成的占主导地位的磁性物种.
主要方法:
- 在大肠杆菌中*C.hydrogenoformans*ACS的异质表达.
- 快速结灭电子偏磁共振 (RFQ-EPR) 光谱学. 快速结灭电子偏磁共振 (RFQ-EPR) 光谱.
- 停止流的红外光谱学 (SF-IR). 停止流的红外光谱学.
主要成果:
- ACS与CO的反应形成了一个单一的金属碳烯物种.
- 通过SF-IR测量的这种物种的形成速度与RFQ-EPR观察到的偏磁NiFeC物种的形成速度相关.
- 溶液中占主导地位的NiFeC物种含有近接Ni在+1氧化还原状态和2+状态的4Fe-4S集群.
结论:
- 在与CO反应时,NiFeC物种是ACS的主要形式.
- 在酶的活性碳化形式中没有证据表明Ni(0) 或Ni(II) 状态.
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