Electrostatic effects in hemoglobin: electrostatic energy associated with allosteric transition and effector binding.
Electrostatic effects in hemoglobin: electrostatic energy associated with allosteric transition and effector binding.
复制标题
血红蛋白中的静电效应：与变构转变和效应器结合相关的静电能。
作者：
J. B. Matthew;S. Friend;F. Gurd
脱氧和配位血红蛋白的总静电稳定的pH依赖性计算几个离子强度值。计算的2，3-二磷酸甘油酸在β裂隙中的结合对脱氧血红蛋白稳定性的贡献与人血红蛋白A0和血红蛋白F的实验结合行为进行了比较。对于血红蛋白A0和F，正确计算了二磷酸甘油酸结合对碱性玻尔效应的贡献。计算出的同时结合二磷酸甘油酸和形成瓦尔-1 β氨基甲酸加合物的效应表明这些效应物之间存在竞争。在这两种效应物之间形成直接竞争，延伸至包括简单阴离子，例如与二磷酸甘油酸竞争结合的氯离子或碳酸氢根，但不与瓦尔-1 β氨基甲酸形成竞争。发现该模型在pH 7.3-7.4下在所涉及的效应物的浓度范围内保持不变，并预测在pH 7.0-8.0范围内形成瓦尔-1 β氨基甲酸酯的pH依赖性。计算的配体与未配体血红蛋白A的微分稳定性的pH依赖性与观察结果相比很好。
The pH dependence of the summed electrostatic stabilization for deoxy- and liganded hemoglobin was computed for several ionic strength values. The computed contribution to the stabilization of deoxyhemoglobin by binding of 2,3-diphosphoglycerate in the beta cleft compared well with experimental binding behavior for human hemoglobin A0 and hemoglobin F. The contribution of diphosphoglycerate binding to the alkaline Bohr effect was computed correctly for both hemoglobins A0 and F. The computed effects of simultaneous binding of diphosphoglycerate and formation of Val-1 beta carbamino adducts suggested a competition between these effectors. A direct competition was formulated between these two effectors, with extension to include a simple anion such as chloride or bicarbonate binding in competition with diphosphoglycerate but not with Val-1 beta carbamino formation. This model was found to hold at pH 7.3-7.4 over a range of concentrations of the effectors involved and to predict the pH dependence of Val-1 beta carbamino formation over the pH range 7.0-8.0. The pH dependence of the computed differential stability of liganded vs. unliganded hemoglobin A compared well with observation.