Resonance Raman interrogation of the consequences of heme rotational disorder in myoglobin and its ligated derivatives.
Resonance Raman interrogation of the consequences of heme rotational disorder in myoglobin and its ligated derivatives.
复制标题
共振拉曼询问肌红蛋白及其连接衍生物中血红素旋转障碍的后果。
DOI：
10.1021/bi801779d
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发表时间：
2008
期刊：
影响因子：
2.9
通讯作者：
Kincaid,JamesR
中科院分区：
文献类型：
--
作者：
Rwere,Freeborn;Mak,PiotrJ;Kincaid,JamesR
利用共振拉曼光谱表征了脱氧Mb及其连接衍生物，即亚铁(MbCO)和氰化铁(MbCN)络合物的构象异质性引起的血红素中心结构的变化。从重组样品的光谱中提取了这些衍生物的反向形式的光谱。观察到低频光谱的戏剧性变化，其中新观察到的反转形式的RR模式是使用在四个甲基或四个甲基碳上选择性氢化的原血红素来指定的。有趣的是，虽然从光谱的显著变化中可以推断出外围乙烯基和丙酸基的配置发生了实质性的变化，但内部组氨酸咪唑配体以及Fe−CO和Fe−CN片段的键并没有受到血红素旋转的显著影响，这是由ν(Fe−NHIS)、ν(Fe−C)和ν(C−O)模式没有显著变化来判断的。事实上，Fe−NHI、Fe−CO和Fe−CN片段的这些关键振动参数明显缺乏影响，这与之前报道的平衡和动力学研究完全一致，这些研究记录了天然形式和反向形式几乎相同的功能性质。
Resonance Raman spectroscopy is employed to characterize heme site structural changes arising from conformational heterogeneity in deoxyMb and ligated derivatives, i.e., the ferrous CO (MbCO) and ferric cyanide (MbCN) complexes. The spectra for the reversed forms of these derivatives have been extracted from the spectra of reconstituted samples. Dramatic changes in the low-frequency spectra are observed, where newly observed RR modes of the reversed forms are assigned using protohemes that are selectively deuterated at the four methyl groups or at the four methine carbons. Interestingly, while substantial changes in the disposition of the peripheral vinyl and propionate groups can be inferred from the dramatic spectral shifts, the bonds to the internal histidyl imidazole ligand and those of the Fe−CO and Fe−CN fragments are not significantly affected by the heme rotation, as judged by lack of significant shifts in the ν(Fe−NHis), ν(Fe−C), and ν(C−O) modes. In fact, the apparent lack of an effect on these key vibrational parameters of the Fe−NHis, Fe−CO, and Fe−CN fragments is entirely consistent with previously reported equilibrium and kinetic studies that document virtually identical functional properties for the native and reversed forms.