Schreiber R D, Noble R W, Reichlin M
J Immunol. 1975 Jan;114(1 Pt 1):170-5.
Previously, we had reported the isolation of an antibody population (termed antiVal antibody) specific for the site of difference between human hemoglobin S(HbS)(beta-6Val) and hemoglobin A-1(BbA)(beta-6 glu). This population has a stoichiometry of reaction of unity in combining with HbS (alpha-beta-dimer) and shows no reaction with HbA. The combination of antiVal Fab fragments with HbS was found to be kinetically homogeneous and had a second order rate constant of 0.58 times 10-6M-1 sec-1 at 20 degrees C. In this report we have studied other properties of the antiVal population. These antibodies are restricted to only one of the two heavy chain subclasses of goat IgG. Electrophoresis experiments indicated that the antiVal population is much less polydisperse than the total antiHbS response. A method was developed to measure the dissociation kinetics of antiVal-HbS complexes. This dissociation was also found to be kinetically homogeneous and could be described by a single first order rate constant of 2.67 times 10-5 sec-1 at 20 degrees C. With homogeneous association and dissociation rate constants, an affinity constant of 2.1 times 10-10M-1 at 20 degrees C was calculated. It appears, then, that this population of antibodies, which are directed toward a single antigenic determinant on a globular protein, exhibit limited structural heterogeneity associated with great functional homogeneity.
此前，我们曾报道过分离出了一群针对人类血红蛋白S（HbS）（β-6缬氨酸）和血红蛋白A-1（HbA）（β-6谷氨酸）之间差异位点的抗体（称为抗缬氨酸抗体）。这群抗体与HbS（α-β二聚体）结合时反应化学计量比为1，且与HbA无反应。发现抗缬氨酸Fab片段与HbS的结合在动力学上是均一的，在20℃时二级速率常数为0.58×10⁻⁶M⁻¹秒⁻¹。在本报告中，我们研究了抗缬氨酸抗体群的其他特性。这些抗体仅局限于山羊IgG的两个重链亚类中的一个。电泳实验表明，抗缬氨酸抗体群的多分散性远低于总的抗HbS反应。开发了一种方法来测量抗缬氨酸-HbS复合物的解离动力学。还发现这种解离在动力学上是均一的，在20℃时可用单一的一级速率常数2.67×10⁻⁵秒⁻¹来描述。根据均一的缔合和解离速率常数，计算出在20℃时的亲和常数为2.1×10⁻¹⁰M⁻¹。那么，看来这群针对球状蛋白上单一抗原决定簇的抗体表现出有限的结构异质性，同时具有高度的功能同质性。
