Tertiary dynamics of human adult hemoglobin fixed in R and T quaternary structures
Tertiary dynamics of human adult hemoglobin fixed in R and T quaternary structures
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DOI：
10.1039/c7cp06287g
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发表时间：
2018-02-07
影响因子：
3.3
通讯作者：
Mizutani, Yasuhisa
中科院分区：
文献类型：
--
作者：
Chang, Shanyan;Mizuno, Misao;Mizutani, Yasuhisa
用时间分辨共振拉曼光谱研究了配体光解后成人血红蛋白及其突变体R和T季态的蛋白质动力学。在时间分辨光谱中，我们观察了所有血红蛋白样品血红素的面内拉伸模式和铁组氨酸的Fe-His键拉伸模式的光谱变化。bD99N突变体在配体结合形式和脱氧形式下均采用R态，在时间分辨共振拉曼光谱中，直到10 μ s，其时间分辨行为与野生型重组血红蛋白相似，这与突变体在R态下只发生三级结构变化的事实一致。β N102T突变体在配体结合和脱氧形式下均采用T态，其三级结构变化要慢得多，这表明亚基间相互作用的改变减缓了EF螺旋运动。目前的数据表明，EF螺旋的螺旋间氢键与亚基间氢键之间的变构动力学响应是双向的。这些结果对理解Hb变构途径的意义进行了详细的讨论。
Protein dynamics of human adult hemoglobin and its mutants restricted in R and T quaternary states following ligand photolysis were studied by time-resolved resonance Raman spectroscopy. In the time-resolved spectra, we observed spectral changes of in-plane stretching modes of heme and the iron-histidine stretching mode of the Fe-His bond for all the hemoglobin samples. The bD99N mutant, which adopts the R state in both the ligand-bound and the deoxy forms, showed similar temporal behaviors in time-resolved resonance Raman spectra as wild-type recombinant hemoglobin until 10 mu s, consistent with the fact that the mutant undergoes only the tertiary structural changes in the R state. The beta N102T mutant, which adopts the T state in both the ligand-bound and the deoxy forms, showed much slower tertiary structural changes, suggesting that the EF helical motion is decelerated by the change of the intersubunit interactions. The present data indicate that the allosteric kinetic response between the interhelical hydrogen bonds of the EF helices and the intersubunit hydrogen bonds is bidirectional. The implications of these results for understanding the allosteric pathway of Hb are discussed in detail.