Haire R N, Hedlund B E
Biochemistry. 1983 Jan 18;22(2):327-34. doi: 10.1021/bi00271a015.
The effects of ethylene glycol (EG) on the oxygen binding properties of human hemoglobin are described in this report. Under the conditions used, the hemoglobin molecule remains in the intact tetrameric form in up to 70% (w/w) EG, corresponding to a mole fraction of EG of 0.4. Interaction between the cosolvent and the hemoglobin is quite weak. Only at high concentrations of EG are the effects on the oxygen binding curve detectable. In the range of mole fraction of EG up to 0.2, oxygen affinity is decreased. In the range of mole fraction of EG between 0.2 and 0.4 (corresponding to molar concentrations of 8-12 M EG), hemoglobin oxygen affinity increases, eventually becoming higher than the value obtained in the absence of EG. Experiments were carried out in the presence of 0.013, 0.10, and 1.0 M NaCl to evaluate the linkage between EG and chloride as allosteric effectors and the possible general effect of ionic strength on oxygen binding properties of hemoglobin in the presence of cosolvent. The effects of EG on hemoglobin ligation are discussed in terms of a model in which EG interacts with hemoglobin in a weak allosteric fashion at the lower concentration range (less than mole fraction of 0.2) while at the higher range (mole fraction of 0.2-0.4) perturbations of protein hydration lead to stabilization of the high-affinity form of hemoglobin.
本报告描述了乙二醇（EG）对人血红蛋白氧结合特性的影响。在所使用的条件下，血红蛋白分子在高达70%（w/w）的EG中保持完整的四聚体形式，对应EG的摩尔分数为0.4。助溶剂与血红蛋白之间的相互作用相当弱。只有在高浓度的EG下，对氧结合曲线的影响才能检测到。在EG摩尔分数高达0.2的范围内，氧亲和力降低。在EG摩尔分数为0.2至0.4的范围内（对应于8 - 12 M EG的摩尔浓度），血红蛋白氧亲和力增加，最终高于在无EG时获得的值。实验在0.013、0.10和1.0 M NaCl存在下进行，以评估EG与氯离子作为变构效应剂之间的联系以及离子强度对在有助溶剂存在下血红蛋白氧结合特性的可能总体影响。根据一个模型讨论了EG对血红蛋白连接的影响，在该模型中，EG在较低浓度范围（小于摩尔分数0.2）以弱变构方式与血红蛋白相互作用，而在较高范围（摩尔分数0.2 - 0.4）蛋白质水合作用的扰动导致血红蛋白高亲和力形式的稳定。
