Reaction coordinate of a functional model of tyrosinase: spectroscopic and computational characterization.
Reaction coordinate of a functional model of tyrosinase: spectroscopic and computational characterization.
复制标题
DOI：
10.1021/ja807898h
复制
发表时间：
2009-05-13
影响因子：
15
通讯作者：
Solomon EI
中科院分区：
文献类型：
--
作者：
Op't Holt BT;Vance MA;Mirica LM;Heppner DE;Stack TD;Solomon EI
通过双二胺配体N，N′-二叔丁基乙二胺（DBED）与Cu（I）反应合成的μ-η2：η2-过氧二铜（II）配合物是偶联双核铜蛋白酪氨酸酶的功能和光谱模型。该络合物与2，4-二叔丁基苯酚盐在低温下反应以产生邻苯二酚和醌产物的混合物，其通过已经表征的三个中间体（A-C）进行。在153 K下稳定的A被表征为酚盐键合的双-μ-氧代二铜（III）物种，其在193 K下通过亲电芳香取代机制进行到B，推测为儿茶酚盐桥连的偶联双铜（II）物种，其中芳香环畸变是限速步骤。同位素标记表明，在羟基化过程中插入到芳香族底物中的氧来自分子氧，后期邻位H+转移到外源性碱基与C-O键形成有关。质子加到B产生C，从共振拉曼光谱确定为Cu（II）-半醌络合物。C的形成（儿茶酚的氧化和还原成Cu（I））受B的远端桥氧配体的质子化状态控制。平行和对比绘制之间的光谱和计算支持的DBED系统，在这里提出的机制，和实验衍生的耦合双核铜蛋白酪氨酸酶的机制。
The μ-η2:η2-peroxodicopper(II) complex synthesized by reacting the Cu(I) complex of the bis-diamine ligand N,N′-di-tert-butyl-ethylenediamine (DBED) with O2 is a functional and spectroscopic model of the coupled binuclear copper protein tyrosinase. This complex reacts with 2,4-di-tert-butylphenolate at low temperature to produce a mixture of the catechol and quinone products, which proceeds through three intermediates (A – C) that have been characterized. A, stabilized at 153K, is characterized as a phenolate-bonded bis-μ-oxo dicopper(III) species, which proceeds at 193K to B, presumably a catecholate-bridged coupled bis-copper(II) species via an electrophilic aromatic substitution mechanism wherein aromatic ring distortion is the rate-limiting step. Isotopic labeling shows that the oxygen inserted into the aromatic substrate during hydroxylation derives from dioxygen, and a late-stage ortho-H+ transfer to an exogenous base is associated with C-O bond formation. Addition of a proton to B produces C, determined from resonance Raman spectra to be a Cu(II)-semiquinone complex. The formation of C (the oxidation of catecholate and reduction to Cu(I)) is governed by the protonation state of the distal bridging oxygen ligand of B. Parallels and contrasts are drawn between the spectroscopically and computationally supported mechanism of the DBED system, presented here, and the experimentally-derived mechanism of the coupled binuclear copper protein tyrosinase.
登录
查看更多内容
影响因子：
2.8
作者：
Bauernschmitt, R;Ahlrichs, R
通讯作者：
Ahlrichs, R
影响因子：
15
作者：
Henson, MJ;Vance, MA;Solomon, EI
通讯作者：
Solomon, EI
影响因子：
4.4
作者：
BECKE, AD
通讯作者：
BECKE, AD
影响因子：
4.6
作者：
Casella, L;Monzani, E;Ugo, R
通讯作者：
Ugo, R
影响因子：
15
作者：
BALDWIN, MJ;ROOT, DE;SOLOMON, EI
通讯作者：
SOLOMON, EI