CIRCULAR-DICHROISM STUDIES OF LOW-SPIN FERRIC CYTOCHROME-P-450CAM LIGAND COMPLEXES
CIRCULAR-DICHROISM STUDIES OF LOW-SPIN FERRIC CYTOCHROME-P-450CAM LIGAND COMPLEXES
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DOI：
10.1016/0167-4838(83)90178-4
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
DAWSON, JH
中科院分区：
文献类型：
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作者：
ANDERSSON, LA;SONO, M;DAWSON, JH
利用圆二色光谱法研究了恶臭假单胞菌P-450 CAM铁细胞色素的活性部位。血红素Fe的内源性第6配体被广泛的一系列外源性O，N，S和其他中性和阴离子供体配体取代，试图系统地研究影响血红素发色团与其蛋白质环境偶联的空间和电子因素。每个配体类的一般趋势的报告和讨论。CD谱带的波长和强度随配体类型和结构而变化。除了1个复合物外，所有复合物在其δ和Soret带中均表现出负CD最大值。与铁肌红蛋白-硫醇盐复合物的比较表明，细胞色素P-450光谱观察到的负号不是硫醇盐第5配体的性质，而是由细胞色素P-450血红素与其蛋白质环境的不同相互作用引起的。与中性O捐助者的复合物显示CD光谱，最接近的本地低自旋酶的光谱。超卟啉（分裂Soret）细胞色素P-450与硫醇盐、膦和氰化物反式至半胱氨酸盐的复合物具有复杂的CD光谱，反映了Soret π-的固有非简并性。圆周率 *过渡。本文提出的广泛的工作提供了一个经验的基础，用于分析血红素发色团与其蛋白质周围的相互作用，不仅为细胞色素P-450单加氧酶，但也为血红素蛋白一般。
Circular dichroism (CD) spectroscopy was used to probe the active site of bacterial (Pseudomonas putida) ferric cytochrome P-450CAM. The endogenous 6th ligand to the heme Fe was displaced by an extensive series of exogenous O, N, S and other neutral and anionic donor ligands in an attempt to examine systematically the steric and electronic factors that influence the coupling of the heme chromophore to its protein environment. General trends for each ligand class are reported and discussed. Both the wavelengths and the intensities of the CD bands vary with ligand type and structure. All but 1 of the complexes exhibit negative CD maxima in their delta and Soret bands. Comparison to ferric myoglobin-thiolate complexes indicates that the negative sign observed for the cytochrome P-450 spectra is not a property of the thiolate 5th ligand, but arises from a different interaction of the cytochrome P-450 heme with its protein environment. Complexes with neutral O donors display CD spectra that most closely resemble the spectrum of the native low-spin enzyme. Hyperporphyrin (split Soret) cytochrome P-450 complexes with thiolates, phosphines and cyanide trans to cysteinate have complex CD spectra, reflecting the intrinsic non-degeneracy of the Soret .pi.-.pi.* transitions. The extensive work presented herein provides an empirical foundation for use in analyzing the interaction of heme chromophores with their protein surroundings, not only for the cytochrome P-450 monooxygenases but also for heme proteins in general.