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首页> 外文期刊>Biochemistry >Structural Characterization of the Proximal and Distal Histidine Environment of Cytoglobin and Neuroglobin
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Structural Characterization of the Proximal and Distal Histidine Environment of Cytoglobin and Neuroglobin

机译：细胞球蛋白和神经球蛋白近端和远端组氨酸环境的结构表征

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摘要

Cytoglobin (Cgb) and neuroglobin (Ngb) are the first examples of hexacoordinated globins from humans and other vertebrates in which a histidine (His) residue at the sixth position of the heme iron is an endogenous ligand in both the ferric and ferrous forms.Static and time-resolved resonance Raman and FT-IR spectroscopic techniques were applied in examining the structures in the heme environment of these globins.Picosecond time-resolved resonance Raman (ps-TR~3) spectroscopy of transient five-coordinate heme species produced by the photolysis of carbon monoxide (CO) adducts of Cgb and Ngb showed Fe-His stretching (v_(Fe)-His) bands at 229 and 221 cm~(-1),respectively.No time-dependent shift in the v_(Fe-His) band of Cgb and Ngb was detected in the 20-1000 ps time domain,in contrast to the case of myoglobin (Mb).These spectroscopic data,combined with previously reported crystallographic data,suggest that the structure of the heme pocket in Cgb and Ngb is altered upon CO binding in a manner different from that of Mb and that the scales of the structural alteration are different for Cgb and Ngb.The structural property of the heme distal side of the ligand-bound forms was investigated by observing the sets of (v_(Fe-Co),V_(C-O),delta_(Fe-C-O)) and (v_(Fe-NO),V_(N-O),delta_(Fe-N-o) for the CO and nitric oxide (NO) complexes of Cgb and Ngb.A comparison of the spectra of some distal mutants of Cgb (H81A,H81V,R84A,R84K,and R84T) and Ngb (H64A,H64V,K67A,K67R,and K67T) showed that the CO adducts of Cgb and Ngb contained three conformers and that the distal His (His81 in Cgb and His64 in Ngb) mainly contributes to the interconversion of the conformers.These structural characteristics of Cgb and Ngb are discussed in relation to their ligand binding and physiological properties.
机译：细胞球蛋白（Cgb）和神经球蛋白（Ngb）是人类和其他脊椎动物的六配位球蛋白的首例，其中血红素铁第六位的组氨酸（His）残基是铁和亚铁形式的内源性配体。并利用时间分辨共振拉曼光谱和FT-IR光谱技术检查这些球蛋白在血红素环境中的结构。皮秒时间分辨共振拉曼光谱（ps-TR〜3）由瞬态五坐标血红素产生。 Cgb和Ngb的一氧化碳（CO）加合物的光解作用分别显示Fe-His拉伸（v_（Fe）-His）谱带分别在229和221 cm〜（-1）处.v_（Fe-与肌红蛋白（Mb）的情况相比，在20-1000 ps时域中检测到了Cgb和Ngb的His）谱带。这些光谱数据与先前报道的晶体学数据相结合，建议Cgb中的血红素袋结构一男一氧化碳会改变Ngb Cbb和Ngb的结构改变的尺度不同.Cbb和Ngb的结构变化的规模不同。通过观察（v_（Fe-Co）， Cgb和Ngb的CO和一氧化氮（NO）配合物的V_（CO），δ_（Fe-CO））和（v_（Fe-NO），V_（NO），δ_（Fe-No）。 Cgb（H81A，H81V，R84A，R84K和R84T）和Ngb（H64A，H64V，K67A，K67R和K67T）的一些远端突变体的光谱显示，Cgb和Ngb的CO加​​合物包含三个构象异构体，并且远端他的（Cgb中的His81和Ngb中的His64）主要有助于构象体的相互转化。讨论了Cgb和Ngb的这些结构特征，涉及它们的配体结合和生理特性。

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