Fuh Germaine, Wu Ping, Liang Wei-Ching, Ultsch Mark, Lee Chingwei V, Moffat Barbara, Wiesmann Christian
Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080, USA.
J Biol Chem. 2006 Mar 10;281(10):6625-31. doi: 10.1074/jbc.M507783200. Epub 2005 Dec 22.
In the quest to discover new research tools and to develop better agents in the fight against cancer, two antibodies, G6 and B20-4, were isolated from synthetic antibody phage libraries. Unlike the AVASTINtrade mark antibody, a recently approved agent for the treatment of patients with colorectal cancer, B20-4 and G6 bind and block both human and murine vascular endothelial growth factor (VEGF). Here we have analyzed and compared the binding epitopes on VEGF for these three antibodies using alanine-scanning mutagenesis and structural analyses. The epitopes recognized by both synthetic antibodies are conserved between human and mouse VEGF, and they match closely to the receptor epitopes both structurally and functionally. In contrast, the Avastin epitope overlaps minimally with the receptor binding surface and centers around a residue that is not conserved in mouse. Our structural and functional analyses elucidate the cross-species reactivity of all three antibodies and emphasize the potential advantages of antibody generation using phage display as the resulting antibodies do not depend on sequence differences across species and preferentially target natural protein-protein interaction surfaces.
在探索发现新的研究工具以及开发对抗癌症的更有效药物的过程中，从合成抗体噬菌体文库中分离出了两种抗体，即G6和B20 - 4。与阿瓦斯汀（AVASTIN）商标抗体（一种最近被批准用于治疗结直肠癌患者的药物）不同，B20 - 4和G6能结合并阻断人类和小鼠的血管内皮生长因子（VEGF）。在这里，我们使用丙氨酸扫描诱变和结构分析，对这三种抗体在VEGF上的结合表位进行了分析和比较。两种合成抗体识别的表位在人类和小鼠VEGF之间是保守的，并且在结构和功能上都与受体表位紧密匹配。相比之下，阿瓦斯汀的表位与受体结合表面的重叠最小，且集中在小鼠中不保守的一个残基周围。我们的结构和功能分析阐明了所有三种抗体的跨物种反应性，并强调了使用噬菌体展示产生抗体的潜在优势，因为所产生的抗体不依赖于物种间的序列差异，并且优先靶向天然的蛋白质 - 蛋白质相互作用表面。
