抗体-抗原结合免疫图

一张免疫学讲义风格的 IgG 抗体结合抗原示意图。深钴蓝重链与天蓝轻链构成经典 Y 形，Fab 区末端与病原体（棕褐色粗糙衣壳弧面）上的表位形成锁-钥结合。Fc 区底部微发光暗示补体激活。右下角圆形插图以 ribbon-diagram 风格展示一个结合口袋的分子互补性。白色背景，金色高亮结合区，细灰色领线标注，整洁无坐标轴版式。

A clean scientific illustration of an IgG antibody binding to a surface antigen on a pathogen, suitable for an immunology lecture slide. The antibody is rendered in a semi-3D ribbon-cartoon style: two heavy chains in deep cobalt blue, two light chains in sky blue, forming the classic Y shape. The antigen-binding sites (Fab regions) at the top prongs show a lock-and-key fit with two matching epitope protrusions on the pathogen surface, which is depicted as a tan curved surface with a rough texture like a viral capsid. The Fc region at the base glows faintly to indicate complement activation potential. A zoomed circular inset at lower-right shows the molecular complementarity of one binding pocket in ribbon-diagram style (alpha helices as coiled ribbons, beta sheets as arrows). Palette: cobalt and sky-blue antibody, tan pathogen surface, muted gold highlights for binding regions, white background. Clean axis-free layout with minimal grey leader-line annotations.