KappaSelect is an affinity medium that specifically binds to the constant region of the kappa light chain (LC). Obviously, KappaSelect can be used to separate antibody species containing the kappa LC constant region from those lacking that region. However, it is not clear whether this resin can readily separate species containing one kappa LC constant region from those containing two kappa LC constant regions although the former are assumed to bind weaker than the latter. In this work, we demonstrated that antibody species with two kappa LC constant regions binds to the KappaSelect resin much tighter than species with only one kappa LC constant region. Consequently, these two species can be readily separated using this resin. This information not only enriches our knowledge with KappaSelect but also has important practical value. In addition to the sample case used in the current study, there are other cases in which the target protein contains one kappa LC constant region whereas a byproduct contains two kappa LC constant regions. Our finding provides a convenient means for removing such two kappa LC binding site containing byproduct in these cases.

KappaSelect是一种亲和介质，可特异性结合至kappa轻链（LC）的恒定区。显然，KappaSelect可以用于将含有kappa LC恒定区的抗体与缺少该区的抗体区分开。但是，尚不清楚该树脂是否能容易地将包含一个κLC恒定区的物质与包含两个κLC恒定区的物质分离，尽管假定前者的结合力弱于后者。在这项工作中，我们证明了具有两个kappa LC恒定区的抗体与KappaSelect树脂的结合要比只有一个kappa LC恒定区的抗体更紧密。因此，使用该树脂可以容易地分离这两种物质。这些信息不仅使我们了解KappaSelect，而且具有重要的实用价值。除了当前研究中使用的样品外，还有其他情况下目标蛋白含有一个κLC恒定区，而副产物含有两个κLC恒定区。我们的发现为在这些情况下去除含有副产物的两个κLC结合位点提供了便利的方法。