Here, we determined qualitative and quantitative characteristics of the chaperone and immunoglobulin-binding activities of recombinant Skp protein (rSkp) from Yersinia pseudotuberculosis using the methods of dynamic light scattering and surface plasmon resonance. Commercial human polyclonal IgG and Fc and Fab fragments of human IgG were used as substrate proteins. The activity of rSkp strongly depended on the medium pH. The most stable low-molecular-weight complexes with a hydrodynamic radius up to 10 nm were formed by rSkp and protein substrates at acidic pH values. Under these conditions, rSkp exhibited the lowest propensity to self-association and the highest affinity for human IgG and its Fc and Fab fragments, as well as prevented their aggregation most efficiently (i.e., demonstrated the maximal chaperone activity). As the medium pH increased, the affinity of rSkp for IgG and its fragments decreased; rSkp was not able to completely prevent the aggregation of protein substrates, but significantly slowed it down. The obtained information may be of practical interest, since the stability of therapeutic IgG preparations affects their safety and efficacy in medical applications.

中文翻译：

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假结核耶尔森氏菌Skp蛋白的分子伴侣和免疫球蛋白结合活性

在这里，我们使用动态光散射和表面等离子体共振的方法确定了来自假结核耶尔森氏菌的重组 Skp 蛋白 (rSkp) 的分子伴侣和免疫球蛋白结合活性的定性和定量特征。商业人多克隆 IgG 和人 IgG 的 Fc 和 Fab 片段用作底物蛋白。rSkp 的活性强烈依赖于培养基的 pH 值。最稳定的低分子量复合物的流体力学半径可达 10 nm，由 rSkp 和蛋白质底物在酸性 pH 值下形成。在这些条件下，rSkp 表现出最低的自结合倾向和对人 IgG 及其 Fc 和 Fab 片段的最高亲和力，并且最有效地阻止它们的聚集（即表现出最大的分子伴侣活性）。随着培养基 pH 值的增加，rSkp对IgG及其片段的亲和力降低；rSkp 不能完全阻止蛋白质底物的聚集，但可以显着减慢它的速度。获得的信息可能具有实际意义，因为治疗性 IgG 制剂的稳定性会影响其在医疗应用中的安全性和有效性。