Resonance Raman spectroscopy of oxoiron(IV) porphyrin pi-cation radical and oxoiron(IV) hemes in peroxidase intermediates.
Resonance Raman spectroscopy of oxoiron(IV) porphyrin pi-cation radical and oxoiron(IV) hemes in peroxidase intermediates.
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过氧化物酶中间体中氧铁 (IV) 卟啉阳离子自由基和氧铁 (IV) 血红素的共振拉曼光谱。
DOI：
10.1016/j.jinorgbio.2006.01.008
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Hosten,CharlesM
中科院分区：
文献类型：
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作者：
Terner,James;Palaniappan,Vaithianathan;Gold,Avram;Weiss,Raymond;Fitzgerald,MelissaM;Sullivan,AnnM;Hosten,CharlesM
血红素过氧化物酶的催化循环中间体，称为化合物I和II，作为血红素蛋白质的中间体，如末端氧化酶和细胞色素P450酶，以及非血红素铁酶的模型，一直受到人们的长期关注。氧代-铁（IV）卟啉π-阳离子自由基类型的化合物I中间体的共振拉曼信号的报道有时是矛盾的，这是由于光致性引起的并发症，导致化合物I信号看起来与化合物II或其他形式的那些类似。然而，合成系统的研究表明，基于蛋白质的氧代铁（IV）卟啉π-阳离子自由基类型的化合物I中间体应该表现出与非自由基形式不同的振动特征。事实上，来自Caldariomyces fumago的辣根过氧化物酶（HRP）和氯过氧化物酶（CPO）的化合物I中间体确实表现出独特的特征振动光谱。过氧化物酶中间体中假定的氧合铁（IV）键的性质在最近的文献中一直在讨论中，建议FeIVO单元可能更好地描述为FeIV-OH。一般低FeIVO伸缩频率观察到的蛋白质已难以模拟在合成铁基卟啉通过电子捐赠从transaxial配体单独。共振拉曼研究的铁-氧振动的蛋白质物种，是敏感的pH值，氘代，和溶剂氧交换，表明氢键的氧代铁（IV）组内的蛋白质环境有助于显着降低FeIVO频率相对于那些合成的模型化合物。
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin π-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin π-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the FeIVO unit might be better described as FeIV–OH. The generally low FeIVO stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron–oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of FeIVO frequencies relative to those of synthetic model compounds.