Timberlake J W, Wong R B, Poretz R D
Prep Biochem. 1980;10(2):173-90. doi: 10.1080/00327488008061733.
The affinity purified Sophora japonica lectin exhibits an anomalous behavior on polyacrylamide gel electrophoresis (PAGE). Electrophoresis at pH 8.9 produces three protein staining bands. Extraction and re-electrophoresis of the fastest and slowest migrating components demonstrates that the lectin solution is an equilibrium mixture of interconvertible forms. Addition of a bindable saccharide, D-galactose, during PAGE causes the equilibrium to be shifted toward a single form. As indicated by analytical gel filtration, sedimentation velocity ultracentrifugation and ion-exchange chromatography experiments, the equilibrium mixture consists of charge and not molecular weight variants of the native molecule of 132,800 g/m. Results from end-group and cysteine analyses and PAGE in sodium dodecyl sulfate indicate that the native lectin is composed of the non-covalent association of two dissimilar subunits. One subunit consists of two identical polypeptide chains attached by two disulfide bonds and the other subunit of two identical polypeptide chains stabilized by a single cysteine bridge.
亲和纯化的槐豆凝集素在聚丙烯酰胺凝胶电泳（PAGE）中表现出异常行为。在pH 8.9条件下进行电泳会产生三条蛋白质染色带。对迁移最快和最慢的组分进行提取并重新电泳表明，凝集素溶液是可相互转化形式的平衡混合物。在PAGE过程中加入可结合的糖类D-半乳糖会使平衡朝着单一形式移动。如分析凝胶过滤、沉降速度超速离心和离子交换色谱实验所示，平衡混合物由132,800 g/m天然分子的电荷变体而非分子量变体组成。端基分析、半胱氨酸分析以及十二烷基硫酸钠中的PAGE结果表明，天然凝集素由两个不同亚基的非共价缔合组成。一个亚基由通过两个二硫键连接的两条相同多肽链组成，另一个亚基由通过单个半胱氨酸桥稳定的两条相同多肽链组成。
