Spectroscopic and computational studies of α-keto acid binding to Dke1: understanding the role of the facial triad and the reactivity of β-diketones.
Spectroscopic and computational studies of α-keto acid binding to Dke1: understanding the role of the facial triad and the reactivity of β-diketones.
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DOI：
10.1021/ja203005j
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发表时间：
2011-10-12
影响因子：
15
通讯作者：
Solomon, Edward I.
中科院分区：
文献类型：
--
作者：
Diebold, Adrienne R.;Straganz, Grit D.;Solomon, Edward I.
O2 激活单核非血红素铁酶通常具有共同的面部三联体（2 个组氨酸和 1 个羧酸盐（天冬氨酸或谷氨酸）残基），在活性位点连接 FeII。最近在非血红素酶中发现了该基序的例外情况，包括二酮裂解双加氧酶 Dke1 中的 3His 三联体。这种酶用于探索面部三联体在指导反应性中的作用。结合光谱研究（UV-vis 吸收、MCD 和共振拉曼）和 DFT 计算来定义 α-酮酸、4-羟基苯丙酮酸 (HPP) 与 Dke1 活性位点的结合性质，以及该酶在 α-酮酸与双氧反应中表现出的非典型裂解（C2-C3 而不是 C1-C2）模式的起源。 3His 三联体的电荷减少诱导 α-酮酸结合为烯醇化二阴离子，而不是酮单阴离子，发现 α-酮酸与 2His/1 羧酸盐面部三联体酶结合。然后，将从 Dke1 与 α-酮酸底物的反应性中获得的机理见解延伸到了解该酶与其天然底物 acac 的反应机制。这项研究定义了 2His/1 羧酸盐面部三联体在 α-酮酸依赖性单核非血红素铁酶中的关键作用，该酶将结合的 α-酮酸稳定为单阴离子，以进行脱羧，从而提供 O2 活化所需的两个额外电子。
The O2 activating mononuclear non-heme iron enzymes generally have a common facial triad (2 histidine and one carboxylate (Asp or Glu) residue) ligating FeII at the active site. Exceptions to this motif have recently been identified in non-heme enzymes, including a 3His triad in the diketone cleaving dioxygenase Dke1. This enzyme is used to explore the role of the facial triad in directing reactivity. A combination of spectroscopic studies (UV-vis absorption, MCD, and resonance Raman) and DFT calculations is used to define the nature of the binding of the α-keto acid, 4-hydroxyphenlpyruvate (HPP), to the active site in Dke1 and the origin of the atypical cleavage (C2–C3 instead of C1–C2) pattern exhibited by this enzyme in the reaction of α-keto acids with dioxygen. The reduced charge of the 3His triad induces α-keto acid binding as the enolate dianion, rather than the keto monoanion, found for α-keto acid binding to the 2His/1 carboxylate facial triad enzymes. The mechanistic insight from the reactivity of Dke1 with the α-keto acid substrate is then extended to understand the reaction mechanism of this enzyme with its native substrate, acac. This study defines a key role for the 2His/1 carboxylate facial triad in α-keto acid dependent mononuclear non-heme iron enzymes in stabilizing the bound α-keto acid as a monoanion for its decarboxylation to provide the two additional electrons required for O2 activation.
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影响因子：
15
作者：
Neidig, ML;Kavana, M;Solomon, EI
通讯作者：
Solomon, EI
影响因子：
2.9
作者：
Diebold, Adrienne R.;Neidig, Michael L.;Moran, Graham R.;Straganz, Grit D.;Solomon, Edward I.
通讯作者：
Solomon, Edward I.
影响因子：
15
作者：
Ho, RYN;Mehn, MP;Que, L
通讯作者：
Que, L
影响因子：
15
作者：
Neidig, Michael L.;Brown, Christina D.;Solomon, Edward I.
通讯作者：
Solomon, Edward I.
影响因子：
4.1
作者：
Straganz, GD;Glieder, A;Steiner, W
通讯作者：
Steiner, W