Szabo A, Karplus M
Biochemistry. 1976 Jun 29;15(13):2869-77. doi: 10.1021/bi00658a026.
The interaction of organic phosphates with hemoglobin is studied by use of a simple thermodynamic approach. A model-independent analysis is employed to evaluate the accuracy of Adair constants determined in the presence of 2,3-diphosphoglycerate (DPG). The change of oxygen affinity in the presence of phosphates is related to the macroscopic phosphate binding constants of oxy- and deoxyhemoglobin and used to extract such binding constants from oxygen equilibrium measurements. The change of the Bohr effect in the presence of phosphates and the competitive binding of carbon dioxide and DPG are treated quantitatively. The binding of organic phosphates is incorporated into an allosteric model, in which the effect of phosphate on both tertiary and quaternary structure changes is included. By use of this model, the factors which can be responsible for the increased functional heterogeneity of alpha and beta chains in the presence of phosphates are clarified.
采用一种简单的热力学方法研究有机磷酸盐与血红蛋白的相互作用。运用与模型无关的分析方法来评估在2,3-二磷酸甘油酸（DPG）存在下测定的阿代尔常数的准确性。磷酸盐存在时氧亲和力的变化与氧合血红蛋白和脱氧血红蛋白的宏观磷酸盐结合常数相关，并用于从氧平衡测量中提取此类结合常数。定量处理了磷酸盐存在时玻尔效应的变化以及二氧化碳和DPG的竞争性结合。将有机磷酸盐的结合纳入一个变构模型，其中包括了磷酸盐对三级和四级结构变化的影响。通过使用该模型，阐明了在磷酸盐存在下可能导致α链和β链功能异质性增加的因素。
