Cupane A, Vitrano E, Cordone L
J Mol Biol. 1986 May 20;189(2):343-51. doi: 10.1016/0022-2836(86)90514-0.
We have studied the effect of organic co-solvents (monohydric alcohols and formamide) on the dimer-tetramer equilibrium of human haemoglobin by measuring the dependence of oxygen affinity upon haemoglobin concentration over a 100-fold concentration range and analysing the data with a modified Monod-Wyman-Changeux model in which the equilibrium (tetramer) in equilibrium with (dimer) + (dimer) was taken into account. This procedure enabled us to obtain the dimer-tetramer equilibrium constant and to find its dependence upon co-solvent concentration. Then by following the procedure already reported for the tense----relaxed state transition of haemoglobin, we separated the co-solvent effects into bulk electrostatic and non-bulk electrostatic (hydrophobic) contributions. We believe that our results demonstrate that during haemoglobin dissociation, just as we have already shown for the tense to relaxed state transition, both charged groups and hydrophobic surfaces became exposed to the solvent.
我们通过测量在100倍浓度范围内氧亲和力对血红蛋白浓度的依赖性，并使用修正的莫诺德-怀曼-尚热模型（该模型考虑了（四聚体）与（二聚体）+（二聚体）处于平衡状态）来分析数据，研究了有机共溶剂（一元醇和甲酰胺）对人血红蛋白二聚体-四聚体平衡的影响。该方法使我们能够获得二聚体-四聚体平衡常数，并找出其对共溶剂浓度的依赖性。然后，按照已报道的血红蛋白从紧张态到松弛态转变的方法，我们将共溶剂效应分为本体静电贡献和非本体静电（疏水）贡献。我们认为，我们的结果表明，在血红蛋白解离过程中，就如同我们已经证明的从紧张态到松弛态的转变一样，带电基团和疏水表面都暴露于溶剂中。
