Insight into the mechanism of an iron dioxygenase by resolution of steps following the FeIV=O species
Insight into the mechanism of an iron dioxygenase by resolution of steps following the FeIV=O species
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DOI：
10.1073/pnas.0911565107
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发表时间：
2010-03-02
影响因子：
11.1
通讯作者：
Proshlyakov, Denis A.
中科院分区：
文献类型：
--
作者：
Grzyska, Piotr K.;Appelman, Evan H.;Proshlyakov, Denis A.
铁加氧酶产生难以捉摸的瞬时氧物种，以催化底物在广泛的代谢过程中的氧化。在这里，我们解决的反应序列和结构的原型非血红素铁-II和α-酮戊二酸依赖性双加氧酶TauD这样的中间体。具有（OO）-O-16-O-18氧的初始物种的时间分辨拉曼光谱明确地建立了Fe-IV=O结构。H-1/H-2取代揭示了氧代基团与底物牛磺酸的C1质子之间的直接相互作用。两个新的瞬态物种被解决后，Fe-IV=O;一个被分配到一个Fe-III-O（H）物种的nu（FeO）模式，第二个可能是从金属配位的含氧产物，如Fe-II-O-C-1或Fe-II-OOCR的振动。这些结果提供了直接洞察底物氧化的机制，并提出了一种替代羟基自由基再结合的范例。
Iron oxygenases generate elusive transient oxygen species to catalyze substrate oxygenation in a wide range of metabolic processes. Here we resolve the reaction sequence and structures of such intermediates for the archetypal non-heme Fe-II and alpha-ketoglutarate-dependent dioxygenase TauD. Time-resolved Raman spectra of the initial species with (OO)-O-16-O-18 oxygen unequivocally establish the Fe-IV=O structure. H-1/H-2 substitution reveals direct interaction between the oxo group and the C1 proton of substrate taurine. Two new transient species were resolved following Fe-IV=O; one is assigned to the nu(FeO) mode of an Fe-III-O(H) species, and a second is likely to arise from the vibration of a metal-coordinated oxygenated product, such as Fe-II-O-C-1 or Fe-II-OOCR. These results provide direct insight into the mechanism of substrate oxygenation and suggest an alternative to the hydroxyl radical rebinding paradigm.