Huang Tao, Chen Xueling, Gu Huan, Zhao Conghui, Liu Xingmu, Yan Meiling, Deng Xiaodong, Zhang Zaiping, Gu Jiang
Department of Pathology and Provincial Key Laboratory of Infectious Diseases and Immunopathology, Collaborative and Creative Center, Molecular Diagnosis and Personalized Medicine, Shantou University Medical College, Shantou, Guangdong, 515041, China.
Department of Oral Pathology, Beijing Stomatological Hospital, Capital Medical University, Beijing, 100050, China.
Oncotarget. 2016 May 24;7(21):31166-76. doi: 10.18632/oncotarget.9085.
Concanavalin A (ConA) chromatography has been extensively used to separate asymmetric Immunoglobulin G (IgG), which possesses oligosaccharide attached to one of the two F(ab')2 arms, from symmetric IgG with no glycan attached to Fab fragments. In this study, applying affinity chromatography, silver stain, Western blot and lectin stain techniques, N- linked oligosaccharide attached to Fab fragment was demonstrated to be exposed on the surface of the protein and be accessible by ConA. In contrast, N- linked oligosaccharide attached to asparagine (Asn) 297 of IgG Fc was located in the inside of the natural protein and was inaccessible by ConA. In addition to asymmetric IgG, there are also detectable level of IgG with both F(ab')2 arms glycosylated that has not been reported previously. The discoveries of new basic molecular structure of IgG would have implications in understanding the function and properties of this important immune molecule with clinical applications.
伴刀豆球蛋白A（ConA）色谱法已被广泛用于分离不对称免疫球蛋白G（IgG），这种IgG在两个F(ab')2臂之一上连接有寡糖，与Fab片段上未连接聚糖的对称IgG相区分。在本研究中，应用亲和色谱、银染、蛋白质印迹和凝集素染色技术，证明连接到Fab片段上的N-连接寡糖暴露于蛋白质表面且可被ConA识别。相比之下，连接到IgG Fc的天冬酰胺（Asn）297上的N-连接寡糖位于天然蛋白质内部，不能被ConA识别。除了不对称IgG外，还可检测到两个F(ab')2臂均糖基化的IgG水平，这是以前未报道过的。IgG新基本分子结构的发现对于理解这种重要免疫分子的功能和特性及其临床应用具有重要意义。
