Ascenzi P, Coletta M, Desideri A, Polizio F, Condò S G, Giardina B
Department of Biochemical Sciences, University of Rome La Sapienza, Italy.
J Inorg Biochem. 1990 Oct;40(2):157-62. doi: 10.1016/0162-0134(90)80049-4.
The effect of inositol hexakisphosphate (IHP) on the spectroscopic (EPR and absorbance) properties of the nitric oxide derivative of ferrous horse and bovine hemoglobin (Hb) has been investigated. In the absence of IHP, the nitric oxide derivative of ferrous horse Hb shows spectroscopic properties similar to those of the corresponding derivative of ferrous human Hb that are generally taken as typical of the high affinity state of tetrametric hemoproteins. Similar to human Hb, the addition of IHP to the nitric oxide derivative of ferrous horse Hb induces a transition toward a species characterized by spectral properties typical of the low affinity state of hemoglobins. Nevertheless, the equilibrium constant for IHP binding to the nitric oxide derivative of ferrous horse Hb (= 1.5 x 10(2) M-1) is much lower than that reported for the association of the polyphosphate to the same derivative of ferrous human Hb (greater than 3 x 10(5) M-1). Conversely, the spectroscopic properties of the nitric oxide derivative of ferrous bovine Hb are characteristic of the low affinity state of tetrameric hemoproteins, both in the absence and in the presence of IHP. These results, taken together with the behavior of the nitric oxide derivative of ferrous human Hb, provide further evidence for the peculiar oxygen binding properties of horse and bovine Hb.
已研究了肌醇六磷酸（IHP）对亚铁马血红蛋白和牛血红蛋白（Hb）一氧化氮衍生物的光谱性质（电子顺磁共振和吸光度）的影响。在不存在IHP的情况下，亚铁马Hb的一氧化氮衍生物显示出与亚铁人Hb相应衍生物相似的光谱性质，这些性质通常被视为四聚体血红蛋白高亲和力状态的典型特征。与人类Hb相似，向亚铁马Hb的一氧化氮衍生物中添加IHP会诱导向一种具有血红蛋白低亲和力状态典型光谱性质的物种转变。然而，IHP与亚铁马Hb一氧化氮衍生物结合的平衡常数（= 1.5 x 10² M⁻¹）远低于报道的多磷酸盐与亚铁人Hb相同衍生物缔合的平衡常数（大于3 x 10⁵ M⁻¹）。相反，无论有无IHP，亚铁牛Hb一氧化氮衍生物的光谱性质都是四聚体血红蛋白低亲和力状态的特征。这些结果与亚铁人Hb一氧化氮衍生物的行为一起，为马和牛Hb独特的氧结合特性提供了进一步的证据。
