Li R, Nagai Y, Nagai M
School of Health Sciences, Kanazawa University Faculty of Medicine, Kanazawa, Japan.
Chirality. 2000 May;12(4):216-20. doi: 10.1002/(SICI)1520-636X(2000)12:4<216::AID-CHIR8>3.0.CO;2-4.
The CD band of human adult hemoglobin (Hb A) at 280 approximately 290 nm shows a pronounced change from a small positive band to a definite negative band on the oxy (R) to deoxy (T) structural transition. This change has been suggested to be due to environmental alteration of Tyrs (alpha42, alpha140, and beta145) or beta37 Trp residues located at the alpha1beta2 subunit interface by deoxygenation. In order to evaluate contributions of alpha140Tyr and beta37Trp to this change of CD band, we compared the CD spectra of two mutant Hbs, Hb Rouen (alpha140Tyr-->His) and Hb Hirose (beta37Trp-->Ser) with those of Hb A. Both mutant Hbs gave a distinct, but smaller negative CD band at 287nm in the deoxy form than that of deoxyHb A. Contributions of alpha140Tyr and beta37Trp to the negative band at the 280 approximately 290 nm region were estimated from difference spectra to be 30% and 26%, respectively. These results indicate that the other aromatic amino acid residues, alpha42Tyr and beta145Tyr, at the alpha1beta2 interface, are also responsible for the change of the CD band upon the R-->T transition of Hb A.
成人血红蛋白（Hb A）在280至290纳米处的圆二色（CD）谱带显示，在从氧合（R）结构向脱氧（T）结构转变时，有一个明显变化，即从小的正峰变为明确的负峰。有人认为这种变化是由于脱氧作用导致位于α1β2亚基界面的酪氨酸残基（α42、α140和β145）或β37色氨酸残基的环境改变所致。为了评估α140酪氨酸和β37色氨酸对CD谱带这一变化的贡献，我们将两种突变血红蛋白Hb Rouen（α140酪氨酸→组氨酸）和Hb Hirose（β37色氨酸→丝氨酸）的CD光谱与Hb A的CD光谱进行了比较。两种突变血红蛋白在脱氧形式下于287纳米处均给出了一个明显但较小的负CD谱带，比脱氧Hb A的负CD谱带小。根据差示光谱估计，α140酪氨酸和β37色氨酸对280至290纳米区域负谱带的贡献分别为30%和
