Herskovits T T, Cavanagh S M, San George R C
Biochemistry. 1977 Dec 27;16(26):5795-801. doi: 10.1021/bi00645a024.
The effectiveness of various salts of the Hofmeister series as dissociating agents for human hemoglobin A tetramers has been investigated by light-scattering molecular-weight measurements. Dissociation of hemoglobin to half-molecules of alpha beta dimers follows the order of the series dictated predominantly by the sequence of the anions F- less than Cl- less than Br- less than ClO4- less than SCN-, I-, with the cations Na+ and K+ having relatively little effect on the observed dissociation. The use of equations derived for predicting the effects of dissociating reagents on the structure of subunit proteins [Herskovits, T. T., and Ibanez, V. S. (1976), Biochemistry 15, 5715] together with Setschenow constants based on the model amino acid data of Nandi and Robinson were found to give a satisfactory account of the dissociation behavior observed with many of the salts, giving reasonable estimates of the number of amino acids that form the smaller contact area of the alpha beta subunits of hemoglobin shown by the Perutz crystallographic model. The analysis of the dissociation data also extends the utility of the Setschenow constants tested for the characterization of the dissociation behavior of other subunit proteins.
通过光散射分子量测量，研究了霍夫迈斯特系列各种盐类作为人血红蛋白A四聚体解离剂的有效性。血红蛋白解离为αβ二聚体半分子的顺序遵循该系列顺序，主要由阴离子顺序决定：F⁻＜Cl⁻＜Br⁻＜ClO₄⁻＜SCN⁻、I⁻，阳离子Na⁺和K⁺对观察到的解离影响相对较小。使用基于Nandi和Robinson的模型氨基酸数据得出的用于预测解离试剂对亚基蛋白质结构影响的方程以及Setschenow常数，发现能够令人满意地解释许多盐类观察到的解离行为，对形成血红蛋白αβ亚基较小接触面积的氨基酸数量给出了合理估计，该接触面积由佩鲁茨晶体学模型显示。对解离数据的分析还扩展了用于表征其他亚基蛋白质解离行为的Setschenow常数的效用。
