White S L
J Biol Chem. 1976 Aug 10;251(15):4763-9.
The results of a series of light scattering experiments of the reaction of inositol hexaphosphate (at pH 7.0) over 6 orders of magnitude of concentration (10(-8) to 10(-2) M) with carboxyhemoglobin indicates that there is a shift in the tetramer-dimer equilibrium towards the tetramer, reaching a maximum effect at 0.1 mM inositol hexaphosphate. Raising the phosphate concentration beyond this latter value promotes dissociation to dimers. However, in this range some of the dissociation of carboxyhemoglobin was undoubtedly due to the increase in ionic strength from the inositol hexaphosphate ion. If the effect of ionic strength is allowed for by classical Debye-Hückel theory, one- and possibly two-phosphate binding sites per dimer can be detected. (Approximate association constant is 8000 M-1 for a single site at 0.1 ionic strength). The location of such sites is considered to lie near the dissociable plane of the hemoglobin tetramer and possibly to include half of the residues that bind inositol hexaphosphate in the tetramer.
对肌醇六磷酸（在pH 7.0条件下）与羧基血红蛋白在6个数量级浓度范围（10⁻⁸至10⁻² M）内反应进行的一系列光散射实验结果表明，四聚体 - 二聚体平衡向四聚体方向移动，在0.1 mM肌醇六磷酸时达到最大效应。将磷酸盐浓度提高到超过该值会促使其解离为二聚体。然而，在此范围内，羧基血红蛋白的一些解离无疑是由于肌醇六磷酸离子导致的离子强度增加。如果根据经典的德拜 - 休克尔理论考虑离子强度的影响，则每个二聚体可检测到一个且可能两个磷酸结合位点。（在0.1离子强度下，单个位点的近似缔合常数为8000 M⁻¹）。这些位点的位置被认为位于血红蛋白四聚体的可解离平面附近，并且可能包括四聚体中结合肌醇六磷酸的一半残基。
