Currell D L, Gattoni M, Chiancone E
Biochim Biophys Acta. 1986 Jun 23;871(3):316-8. doi: 10.1016/0167-4838(86)90214-1.
The binding of chloride ions to specific sites on the human hemoglobin molecule has well-known effects on the oxygen equilibrium and on the stability of the tetrameric structure. Several lines of evidence suggest that the oxygen-linked and the dissociation-linked chloride binding sites differ. Direct evidence for this difference has been obtained from the chloride dependence of the dimer-tetramer equilibrium of oxyhemoglobin modified with 4-isothiocyanatobenzenesulfonic acid, in which all the oxygen-linked chloride binding sites are blocked, or with 4-isothiocyanatobenzenesulfonamide, in which the linkage between chloride and oxygen is unperturbed. Thus, the chloride dependence of the dimer-tetramer assembly is unaffected by the chemical modification in both proteins and resembles that of unreacted hemoglobin. It is suggested that histidines alpha-103, alpha-122 and beta-97 may constitute, at least in part, the dissociation-linked chloride binding sites.
氯离子与人类血红蛋白分子上的特定位点结合，对氧平衡和四聚体结构的稳定性具有众所周知的影响。几条证据表明，与氧结合的氯离子结合位点和解离相关的氯离子结合位点有所不同。这种差异的直接证据来自于用4-异硫氰酸苯磺酸修饰的氧合血红蛋白（其中所有与氧结合的氯离子结合位点均被阻断）或用4-异硫氰酸苯磺酰胺修饰的氧合血红蛋白（其中氯离子与氧之间的联系未受干扰）的二聚体-四聚体平衡对氯离子的依赖性。因此，二聚体-四聚体组装对氯离子的依赖性在两种蛋白质中均不受化学修饰的影响，并且类似于未反应的血红蛋白。有人提出，α-103、α-122和β-97组氨酸可能至少部分构成了解离相关的氯离子结合位点。
