Ghirlando R, Lund J, Goodall M, Jefferis R
Department of Immunology, The Medical School Birmingham, UK.
Immunol Lett. 1999 May 3;68(1):47-52. doi: 10.1016/s0165-2478(99)00029-2.
Glycosylation of the Fc region of IgG (IgG-Fc) is essential for the full expression of Fc effector functions. The profound differences in functional activity observed between glycosylated and aglycosylated IgG have not previously been paralleled by the demonstration of large-scale structural changes. In the present study differential scanning microcalorimetry (DSMC) was used to investigate IgG-Fc glycoprotein stability and to determine the thermodynamic parameters for thermal unfolding, which will include a contribution from the intra-molecular oligosaccharide-protein interactions. The thermogram obtained for glycosylated IgG1-Fc yielded two clearly defined transitions whilst the glycosylated IgG4-Fc exhibited a single transition. The methodology was also able to reveal measurable differences in the stability of IgG4-Fc glycoforms differing by the presence or absence of terminal galactose residues; deglycosylated IgG4-Fc exhibited two transitions with evidence for destabilisation of the C(H)2 domain.
免疫球蛋白G（IgG）的Fc区域糖基化对于Fc效应功能的充分表达至关重要。此前，糖基化和去糖基化IgG之间观察到的功能活性的显著差异，并未伴随着大规模结构变化的证明。在本研究中，差示扫描量热法（DSMC）被用于研究IgG-Fc糖蛋白的稳定性，并确定热解折叠的热力学参数，其中将包括分子内寡糖-蛋白质相互作用的贡献。糖基化IgG1-Fc获得的热谱图产生了两个明确定义的转变，而糖基化IgG4-Fc表现出单一转变。该方法还能够揭示因存在或不存在末端半乳糖残基而不同的IgG4-Fc糖型在稳定性上的可测量差异；去糖基化的IgG4-Fc表现出两个转变，有证据表明C(H)2结构域不稳定。
