Cupane A, Vitrano E
Biochim Biophys Acta. 1986 Sep 5;873(1):1-5. doi: 10.1016/0167-4838(86)90181-0.
We have studied the effect of sodium maleate on the reaction of haemoglobin with oxygen at various temperatures between 10 degrees C and 30 degrees C. At all the temperatures investigated, the presence of sodium maleate causes a significant increase of log p50. Analysis of the experimental data in terms of Wyman's linkage theory indicates that one oxygen-linked maleate molecule bound to the haemoglobin tetramer in the deoxy conformation is released when the tetramer is oxygenated. Further analysis within the framework of the Monod-Wyman-Changeux model, considering maleate as a classical allosteric inhibitor, enabled us to obtain the equilibrium constant for the binding of maleate to deoxyhaemoglobin at various temperatures and therefore the values of the standard binding entropy and enthalpy. These last values indicate that the binding of maleate to deoxyhaemoglobin is an exothermic enthalpy-driven process.
我们研究了马来酸钠在10℃至30℃之间的不同温度下对血红蛋白与氧气反应的影响。在所研究的所有温度下，马来酸钠的存在都会导致log p50显著增加。根据怀曼的连锁理论对实验数据进行分析表明，当四聚体被氧合时，一个与脱氧构象的血红蛋白四聚体结合的氧连接马来酸分子会被释放。在莫诺-怀曼-尚热模型的框架内进行进一步分析，将马来酸视为经典的别构抑制剂，使我们能够获得马来酸在不同温度下与脱氧血红蛋白结合的平衡常数，从而得到标准结合熵和焓的值。这些最后的值表明，马来酸与脱氧血红蛋白的结合是一个由焓驱动的放热过程。
