Wilson I A, Stanfield R L, Rini J M, Arevalo J H, Schulze-Gahmen U, Fremont D H, Stura E A
Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.
Ciba Found Symp. 1991;159:13-28; discussion 28-39. doi: 10.1002/9780470514108.ch3.
The structures of several Fab fragments and Fab-antigen complexes have now been solved at high resolution. These structures of antibodies in complex with proteins, peptides and various other haptens have enabled us to gain insights into the structural basis of immune recognition. Early structures of Fab fragments with and without bound haptens showed the antibody combining sites to be pockets or grooves. More recent Fab-protein complex structures have shown the antibody-antigen interactions to be more extensive with flatter, more undulating binding surfaces. We have solved the structures of three Fab fragments in their native form and as complexes with their respective antigens. Two of these are anti-peptide Fab fragments, the other an anti-progesterone Fab. Comparison of the free and bound structures indicates small but significant changes in the antibody on ligand binding. An analysis of the Fab complexes solved so far indicates that the antibodies can have very differently shaped binding sites, depending on the antigen.
目前，几个Fab片段以及Fab-抗原复合物的结构已得到高分辨率解析。这些抗体与蛋白质、肽及各种其他半抗原形成复合物的结构，使我们得以深入了解免疫识别的结构基础。有结合半抗原和无结合半抗原的Fab片段早期结构显示，抗体结合位点为口袋或凹槽。最近的Fab-蛋白质复合物结构表明，抗体-抗原相互作用在更平坦、更起伏的结合表面上更为广泛。我们解析了三个Fab片段的天然形式及其与各自抗原形成复合物的结构。其中两个是抗肽Fab片段，另一个是抗孕酮Fab。游离和结合结构的比较表明，配体结合时抗体发生了微小但显著的变化。对目前已解析的Fab复合物的分析表明，根据抗原不同，抗体可具有形状差异很大的结合位点。
