Set of Fe(II)-3-Hydroxyflavonolate Enzyme−Substrate Model Complexes of Atypically Coordinated Mononuclear Non-Heme Fe(II)-Dependent Quercetin 2,4-Dioxygenase
Set of Fe(II)-3-Hydroxyflavonolate Enzyme−Substrate Model Complexes of Atypically Coordinated Mononuclear Non-Heme Fe(II)-Dependent Quercetin 2,4-Dioxygenase
复制标题
Fe(II)-3-羟基黄酮酸酶 — 非典型协调单核非血红素 Fe(II) 依赖性槲皮素 2,4-双加氧酶的底物模型复合物组
DOI：
10.1021/acsomega.7b00927
复制
发表时间：
2017
期刊：
影响因子：
4.1
通讯作者：
Jian-Jun Zhang
中科院分区：
文献类型：
--
作者：
Ying-Ji Sun;Qian-Qian Huang;Jian-Jun Zhang
目的是揭示催化剂的催化作用，（3 His-1Glu）活性位点单核非血红素Fe（II）依赖性槲皮素2，4-双加氧酶（Fe-2，4-QD）和模型配体对分子氧反应性的电子效应，一组p/m-R-取代的含羧酸配体的Fe（II）-3-羟基黄酮配合物[FeIILR（弗拉）]（LRH：2-{[双（吡啶-2-基甲基）氨基]甲基}-p/m-R-苯甲酸; R：p-OMe（1），p-Me（2），m-Br（4），和m-NO2（5）;弗拉：3-羟基黄酮），并作为Fe-2，4-QD的ES（酶-底物）络合物的结构和功能模型进行了表征。[FeIILR（弗拉）]在低温（30-65 °C）下显示出相对高的酶型反应性（配位底物弗拉的双氧开环，单翻转反应）。反应呈现线性Hammett曲线（ρ = −1.21），供电子基团提高了反应速率。反应活性的显著差异可以从配体中取代基的电子性质来解释，其可以通过调节Fe（II）离子的刘易斯酸性、电子密度和弗拉的氧化还原电位来调节反应活性。弗拉的λ max或E1/2与反应速率常数k之间呈近似线性关系。这不仅有助于理解配体的电子效应和性质-反应性关系，而且有助于理解Fe-2，4-QD在催化反应中的作用。
With the aim of revealing the catalytic role of atypically coordinated (3His-1Glu) active site mononuclear non-heme Fe(II)-dependent quercetin 2,4-dioxygenase (Fe-2,4-QD) and the electronic effects of the model ligands on the reactivity toward dioxygen, a set of p/m-R-substituted carboxylate-containing ligand-supported Fe(II)-3-hydroxyflavonolate complexes, [FeIILR(fla)] (LRH: 2-{[bis(pyridin-2-ylmethyl)amino]methyl}-p/m-R-benzoic acid; R:p-OMe (1),p-Me (2),m-Br (4), andm-NO2(5); fla: 3-hydroxyflavonolate), were synthesized and characterized as structural and functional models for the ES (enzyme–substrate) complexes of Fe-2,4-QD. [FeIILR(fla)] show relatively high enzyme-type reactivity (dioxygenative ring opening of the coordinated substrate fla, single-turnover reaction) at low temperatures (30–65 °C). The reaction shows a linear Hammett plot (ρ = −1.21), and electron donating groups enhance the reaction rates. The notable difference on the reactivity can be rationalized from the electronic nature of the substituent in the ligands, which could tune the reactivity via tuning Lewis acidity of the Fe(II) ion, electron density, and the redox potential of fla. The properties and the reactivity show approximately linear correlations between λmaxorE1/2of fla and the reaction rate constantk. This work sheds light not only on understanding of electronic effects of the ligands and the property–reactivity relationship but also on the role of the catalytic reaction by Fe-2,4-QD.