Scott J K, Loganathan D, Easley R B, Gong X, Goldstein I J
Division of Biological Sciences, University of Missouri, Columbia 65211.
Proc Natl Acad Sci U S A. 1992 Jun 15;89(12):5398-402. doi: 10.1073/pnas.89.12.5398.
The lectin concanavalin A (Con A) binds methyl alpha-D-mannopyranoside (Me alpha Man) as well as alpha-D-mannosyl groups at the nonreducing terminus of oligosaccharides. Ligand peptides that mimic the binding of Me alpha Man to Con A were identified from screening an epitope library composed of filamentous phage displaying random hexapeptides. A consensus sequence was identified among affinity-purified phage; Con A binds phage bearing this sequence and is inhibited from doing so by Me alpha Man. When tested for binding against a panel of lectins, phage bearing this sequence bind only weakly to a closely related D-mannose-binding lectin, indicating that binding to Con A is highly selective. A synthetic peptide bearing the consensus sequence blocks the precipitation of Con A by dextran with an inhibition strength equivalent to that of methyl alpha-D-glucopyranoside. These results demonstrate that the specificity of Con A is not limited to carbohydrates and that highly selective sugar-mimics for lectins of plant, animal, or bacterial origin may be identified from epitope libraries.
凝集素伴刀豆球蛋白A（Con A）可结合甲基α-D-甘露吡喃糖苷（MeαMan）以及寡糖非还原端的α-D-甘露糖基。通过筛选由展示随机六肽的丝状噬菌体组成的表位文库，鉴定出了模拟MeαMan与Con A结合的配体肽。在亲和纯化的噬菌体中鉴定出了一个共有序列；Con A可结合带有该序列的噬菌体，而MeαMan可抑制其结合。当测试带有该序列的噬菌体与一组凝集素的结合时，其仅与一种密切相关的D-甘露糖结合凝集素弱结合，这表明与Con A的结合具有高度选择性。带有共有序列的合成肽可阻断葡聚糖对Con A的沉淀作用，其抑制强度与甲基α-D-吡喃葡萄糖苷相当。这些结果表明，Con A的特异性并不局限于碳水化合物，并且可以从表位文库中鉴定出对植物、动物或细菌来源的凝集素具有高度选择性的糖模拟物。
