Relationship of function and higher order structure of abnormal hemoglobin.

为了探讨氧结合功能(变构)与血红蛋白A(Hb A)四级结构变化的关系，我们用紫外圆二色谱(CD)和紫外共振拉曼光谱(UVRR)研究了异常血红蛋白的结构和功能。研究结果如下：(1)Hb四级结构变化的紫外光CD研究：我们研究了α1-β2亚基界面氨基酸取代的异常血红蛋白的UVCD谱(参考文献1，2)：(1)用紫外可见共振拉曼光谱研究了Hb岩手酸和Hb M Boston的血红素和蛋白质结构(参考文献3，4)。(2)用紫外光共振拉曼光谱研究了Hb的结构和功能关系：在235 nm激发下，TYR和Trp RR谱带在脱氧-GT和CO结构转变时发生了变化。我们利用异常的血红蛋白、NO和金属杂合型Hb阐明了哪些酪氨酸或色氨酸残基导致了这些变化(参考文献5-7)。从这些结果中，我们阐明了α1-β2亚基界面上的酪氨酸和/或色氨酸残基对血红蛋白异构化至关重要。这些芳香族残基对血红蛋白的高阶蛋白质结构转变不是独立的，而是协同作用的。

In order to address the relationship between oxygen binding function (allostery) and quaternary structure changes of hemoglobin A (Hb A), we have studied on structure and function of abnormal hemoglobin by ultraviolet (UV) circular dichroism (CD) and UV resonance Raman (UVRR) spectroscopy. The results were summarized as follows :(1) A study of quaternary structure change of Hb by UVCD : We examined UVCD spectra of abnormal hemoglobin with amino acid substitution at α1-β2 subunit interface (References, 1, 2).(1) Heme and protein structure of Hb M Iwate and Hb M Boston characterized by UV and visible resonance Raman study (References, 3, 4).(2) Structural and functional relationship of hemoglobin by UVRR : Tyr and Trp RR bands excited with 235nm changed upon deoxy->oxy(or CO) structure transition. We clarified which Tyr or Trp residue contributed to these changes using abnormal hemoglobin, NO and metal-hybrid Hb (References, 5-7).From these results, we have elucidated that Tyr and/or Trp residues at α1-β2 subunit interface are critically important for hemoglobin allostery. These aromatic residues contribute not independently but cooperatively to higher order protein structure transition of hemoglobin.