Spectroscopic characterization of the ferric states of Amphitrite ornata dehaloperoxidase and Notomastus lobatus chloroperoxidase: His-ligated peroxidases with globin-like proximal and distal properties.
Spectroscopic characterization of the ferric states of Amphitrite ornata dehaloperoxidase and Notomastus lobatus chloroperoxidase: His-ligated peroxidases with globin-like proximal and distal properties.
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Amphitrite ornata 脱卤过氧化物酶和 Notomastus lobatus 氯过氧化物酶的铁态光谱表征：具有珠蛋白样近端和远端特性的 His 连接过氧化物酶。
DOI：
10.1016/j.jinorgbio.2006.02.008
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Dawson,JohnH
中科院分区：
文献类型：
--
作者：
Osborne,RobertL;Sumithran,Suganya;Coggins,MichaelK;Chen,Yung-Pin;Lincoln,DavidE;Dawson,JohnH
双壳藻脱卤素过氧化物酶(DHP)和白念珠菌氯过氧化物酶(NCPO)分别催化依赖过氧化氢的卤代苯酚脱卤化和苯酚的卤化反应。这两种酶都以组氨酸(His)作为其近端的血红素铁配体。DHP的结晶学研究表明它具有珠蛋白折叠[M.W.LaCount，E.Zhang，Y.P.Chen，K.Han.，M.M.Whitton，D.E.林肯，S.A.Woodin，L.Lebioda，J.Biol]。化学。275(2000)18712-18716]，动力学研究证实DHP铁是活性状态[R.L.奥斯本，L.O.泰勒，K.han，B.Ely，J.H.Dawson，Biochem]。生物群落。[中英文摘要]Re.Commun.324(2004)1194-1198]。NCPO很可能具有这些相同的特性。以前对组氨酸连接的血红素蛋白的研究已经揭示了氧结合珠蛋白和过氧化氢激活的过氧化物酶之间的特征光谱差异。由于DHP和可能的NCPO是一种过氧化氢激活的珠蛋白，我们在目前的研究中试图确定这两种新的含血红素的酶的铁休止状态是肌红蛋白样还是过氧化物酶样。为此，我们用紫外可见吸收光谱和磁性圆二色光谱研究了它们的外源无配体铁态以及它们的叠氮、咪唑和无结合铁加合物(以及亚铁-NO络合物)。我们还将每个衍生物与马心脏肌红蛋白(Mb)和辣根过氧化物酶(HRP)的类似状态进行了比较。观察到的平行形式的DHP和NCPO的光谱几乎彼此相同，也与相同Mb态的光谱相同，而与相应的HRP衍生物的光谱不太相似。根据这些数据，我们推测外源无配体的DHP和NCPO与水是六配位的，中性的组氨酸是配体。这种配位结构明显不同于组氨酸连接的过氧化物酶的铁静息状态，表明DHP和NCPO不是通过典型的血红素过氧化物酶的机制激活结合的过氧化氢，这种机制依赖于部分电离的组氨酸近端给予的推动效应。
Amphitrite ornata dehaloperoxidase (DHP) and Notomastus lobatus chloroperoxidase (NCPO) catalyze the peroxide-dependent dehalogenation of halophenols and halogenation of phenols, respectively. Both enzymes have histidine (His) as their proximal heme iron ligand. Crystallographic examination of DHP revealed that it has a globin fold [M.W. LaCount, E. Zhang, Y.-P. Chen, K. Han, M.M. Whitton, D.E. Lincoln, S.A. Woodin, L. Lebioda, J. Biol. Chem. 275 (2000) 18712–18716] and kinetics studies established that ferric DHP is the active state [R.L. Osborne, L.O. Taylor, K. Han, B. Ely, J.H. Dawson, Biochem. Biophys. Res. Commun. 324 (2004) 1194–1198]. NCPO likely has these same properties. Previous work with His-ligated heme proteins has revealed characteristic spectral distinctions between dioxygen binding globins and peroxide-activating peroxidases. Since DHP, and likely NCPO, is a peroxide-activating globin, we have sought to determine in the present investigation whether the ferric resting states of these two novel heme-containing enzymes are myoglobin-like or peroxidase-like. To do so, we have examined their exogenous ligand-free ferric states as well as their azide, imidazole and NO bound ferric adducts (and ferrous–NO complexes) with UV–Visible absorption and magnetic circular dichroism spectroscopy. We have also compared each derivative to the analogous states of horse heart myoglobin (Mb) and horseradish peroxidase (HRP). The spectra observed for parallel forms of DHP and NCPO are virtually identical to each other as well as to the spectra of the same Mb states, while being less similar to the spectra of corresponding HRP derivatives. From these data, we conclude that exogenous ligand-free ferric DHP and NCPO are six-coordinate with water and neutral His as ligands. This coordination structure is distinctly different from the ferric resting state of His-ligated peroxidases and indicates that DHP and NCPO do not activate bound peroxide through a mechanism dependent on a push effect imparted by a partially ionized proximal His as proposed for typical heme peroxidases.
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影响因子：
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作者：
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DOI：
--
发表时间：
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