Identification of the Fe-O-O bending mode in oxycytochrome P450cam by resonance Raman spectroscopy
Identification of the Fe-O-O bending mode in oxycytochrome P450cam by resonance Raman spectroscopy
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DOI：
10.1021/ja9810383
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发表时间：
1999-01-20
影响因子：
15
通讯作者：
Champion, PM
中科院分区：
文献类型：
--
作者：
Macdonald, IDG;Sligar, SG;Champion, PM
氧合野生型细胞色素P450 cam（oxyP 450 cam）在401 cm（-1）处观察到氧敏感模式，并根据O-16（2）、O-18（2）同位素位移（19 cm（-1））以及与Co-和Fe-氧卟啉络合物的比较，将其归属于δ（Fe-O-O）弯曲模式。这种Fe-O-O弯曲模式的检测具有酶功能的结构意义，因为其频率反映了与氧合血红素蛋白活性位点中的Fe-O-O扭曲相关的能量。三体法向坐标计算充分拟合了oxyP 450 cam中Fe-O-O键合的125-130度键角的实验数据集。低频同位素敏感的振动模式，其中一些假设是与平面外卟啉运动的观察也有报道。这些模式，结合这种弯曲模式的高频率和Fe-O-2伸缩模式的异常同位素位移，表明oxyP 450 cam中的“应变”Fe-O-O部分，具有与HbO（2）和MbO（2）相当的迁移率。讨论了这种“菌株”的可能来源以及对P450中催化分子氧活化的影响。
An oxygen-sensitive mode in oxygenated wild-type cytochrome P450cam (oxyP450cam) is observed at 401 cm(-1) and assigned to the delta(Fe-O-O) bending mode, based upon O-16(2),O-18(2) isotopic shifts (19 cm(-1)) and comparison with Co- and Fe-oxyporphyrin complexes. The detection of this Fe-O-O bending mode has structural implications for enzyme function since its frequency reflects the energies associated with Fe-O-O distortion in oxyhemeprotein active sites. Three body normal coordinate calculations adequately fit the experimental data set with a 125-130 degrees bond angle for the Fe-O-O linkage in oxyP450cam. Observation of low-frequency isotope-sensitive vibrational patterns, some of which an hypothesized to be associated with out-of-plane porphyrin motions are also reported. These patterns, in conjunction with the high frequency of this bending mode and the abnormal isotopic shift of the Fe-O-2 stretching mode, suggest a "strained" Fe-O-O moiety in oxyP450cam, with comparable mobility to HbO(2) and MbO(2). Possible sources of this "strain" and implications for catalytic dioxygen activation in P450cam an discussed.