O-H Activation by an Unexpected Ferryl Intermediate during Catalysis by 2-Hydroxyethylphosphonate Dioxygenase.
O-H Activation by an Unexpected Ferryl Intermediate during Catalysis by 2-Hydroxyethylphosphonate Dioxygenase.
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DOI：
10.1021/jacs.6b12147
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发表时间：
2017-02-08
影响因子：
15
通讯作者：
van der Donk WA
中科院分区：
文献类型：
--
作者：
Peck SC;Wang C;Dassama LM;Zhang B;Guo Y;Rajakovich LJ;Bollinger JM Jr;Krebs C;van der Donk WA
无机金属-氧代络合物对O-H键的活化已有文献记载，但没有已知的同源酶促过程。我们对2-羟乙基膦酸酯双加氧酶（HEPD）的机理分析揭示了这种O-H-键断裂事件的一个实例，所述2-羟乙基膦酸酯双加氧酶（HEPD）在商业除草剂膦丝菌素的生物合成途径上切割其底物的C1-C2键以提供羟甲基膦酸酯。停流紫外-可见吸收和冷冻猝灭穆斯堡尔实验确定了一个瞬态铁（IV）-氧代（ferryl）复合物。中间体的最大积累需要在底物中存在氘，重要的是，使用2 H2O作为溶剂。铁基复合物的形成和衰变足够快，足以在催化途径。为了解释这些意想不到的结果，提出了一种新的机制，该机制涉及由铁基复合物激活O-H键。该机制适应关于HEPD反应的所有可用数据。
Activation of O–H bonds by inorganic metal-oxo complexes has been documented, but no cognate enzymatic process is known. Our mechanistic analysis of 2-hydroxyethylphosphonate dioxygenase (HEPD), which cleaves the C1–C2 bond of its substrate to afford hydroxymethylphosphonate on the biosynthetic pathway to the commercial herbicide phosphinothricin, uncovered an example of such an O–H-bond-cleavage event. Stopped-flow UV–visible absorption and freeze-quench Mössbauer experiments identified a transient iron(IV)-oxo (ferryl) complex. Maximal accumulation of the intermediate required both the presence of deuterium in the substrate and, importantly, the use of 2H2O as solvent. The ferryl complex forms and decays rapidly enough to be on the catalytic pathway. To account for these unanticipated results, a new mechanism that involves activation of an O–H bond by the ferryl complex is proposed. This mechanism accommodates all available data on the HEPD reaction.