Nitric Oxide Dioxygenation Reaction by Oxy-Coboglobin Models: In-situ Low-Temperature FTIR Characterization of Coordinated Peroxynitrite
Nitric Oxide Dioxygenation Reaction by Oxy-Coboglobin Models: In-situ Low-Temperature FTIR Characterization of Coordinated Peroxynitrite
复制标题
DOI：
10.1021/ja305774v
复制
发表时间：
2012-08-22
影响因子：
15
通讯作者：
Goodwin, John A.
中科院分区：
文献类型：
--
作者：
Kurtikyan, Tigran S.;Eksuzyan, Shahane R.;Goodwin, John A.
通过NH_3和分子氧与钴卟啉微孔膜的连续低温相互作用，构建了通式为（NH_3）Co（Por）（O-2）（Por = meso-四苯基和meso-四对甲苯基卟啉）的氧钴珠蛋白模型.在低温下，将少量的NO引入低温恒温器中，并在缓慢升温期间通过FTIR和UV-可见光谱监测以下反应。在将层从80 K加热到120 K时，一组新的IR带随着nu（O-2）带的消耗而沿着相关强度生长。O-18（2）、（NO）-N-15和（NO）-O-18的同位素标记实验沿着密度泛函理论计算为将它们归属于六配位过氧亚硝酸根配合物（NH_3）Co（Por）（OONO）提供了基础。在变暖的过程中，从140至170 K的层，这些复合物分解，并有光谱特征表明二氧化氮NO2的形成。在180-210 K的温度下，NO2谱带的强度逐渐降低，新谱带在1480、1270和980 cm（-1）的范围内增长。当在实验中使用（NO）-N-15、O-18（2）和（NO）-O-18时，这些谱带具有它们的同位素对应物，并且肯定属于6配位硝酸根络合物（NH3）Co（Por）（eta（1）-ONO 2），这证明了氧血红蛋白模型促进与氧血红素类似的一氧化氮双氧化（NOD）反应的能力。与IIb、Mb和模型铁卟啉的情况一样，六配位硝酸根配合物在室温下不稳定，并且解离为硝酸根阴离子和氧化的阳离子配合物Co（III）（Por）（NH3）（1，2）。
The oxy-cobolglobin models of the general formula (NH3)Co(Por)(O-2) (Por = meso-tetra-phenyl and meso-tetra-p-tolylpoiphyrinato dianions) were constructed by sequential low temperature interaction of NH3 and dioxygen with microporous layers of Co-porphyrins. At cryogenic temperatures small increments of NO were introduced into the cryostat and the following reactions were monitored by the FTIR and UV-visible spectroscopy during slow warming. Upon warming the layers from 80 to 120 K a set of new IR bands grows with correlating intensities along with the consumption of the nu(O-2) band. Isotope labeling experiments with O-18(2), (NO)-N-15 and (NO)-O-18 along with DFT calculations provides a basis for assigning them to the six-coordinate peroxynitrite complexes (NH3)Co(Por)(OONO). Over the course of warming the layers from 140 to 170 K these complexes decompose and there are spectral features suggesting the formation of nitrogen dioxide NO2. Upon keeping the layers at 180-210 K the bands of NO2 gradually decrease in intensity and the set of new bands grows in the range of 1480, 1270, and 980 cm(-1). These bands have their isotopic counterparts when (NO)-N-15, O-18(2) and (NO)-O-18 are used in the experiments and certainly belong to the 6-coordinate nitrato complexes (NH3)Co(Por)(eta(1)-ONO2) demonstrating the ability of oxy coboglobin models to promote the nitric oxide dioxygenation (NOD) reaction similar to oxy-hemes. As in the case of lib, Mb and model iron-porphyrins, the six-coordinate nitrato complexes are not stable at room temperature and dissociate to give nitrate anion and oxidized cationic complex Co(III)(Por)(NH3)(1,2).