Alexander H, Alexander S, Getzoff E D, Tainer J A, Geysen H M, Lerner R A
Division of Biological Sciences, University of Missouri, Columbia 65211.
Proc Natl Acad Sci U S A. 1992 Apr 15;89(8):3352-6. doi: 10.1073/pnas.89.8.3352.
To better understand the binding interaction between antigen and antibody we need to distinguish protein residues critical to the binding energy and mechanism from residues merely localized in the interface. By analyzing the binding of monoclonal antibodies to recombinant wild-type and mutant myohemerythrin (MHr) proteins, we were able to test the role of individual critical residues at the highly antigenic site MHr-(79-84), within the context of the folded protein. The results directly show the existence of antigenically critical residues, whose mutations significantly reduce antibody binding to the folded protein, thus verifying peptide-based assignments of these critical residues and demonstrating the ability of buried side chains to influence antigenicity. Taken together, these results (i) distinguish the antigenic surface from the solvent-exposed protein surface before binding, (ii) support a two-stage interaction mechanism allowing inducible changes in protein antigens by antibody binding, and (iii) show that protein antigenicity can be significantly reduced by alteration of single critical residues without destroying biological activity.
为了更好地理解抗原与抗体之间的结合相互作用，我们需要区分对结合能量和机制至关重要的蛋白质残基与仅位于界面处的残基。通过分析单克隆抗体与重组野生型和突变型肌红蛋白（MHr）蛋白的结合情况，我们能够在折叠蛋白的背景下测试高度抗原性位点MHr-(79-84)处单个关键残基的作用。结果直接表明存在抗原性关键残基，其突变会显著降低抗体与折叠蛋白的结合，从而验证了这些关键残基基于肽段的归属，并证明了埋藏侧链影响抗原性的能力。综上所述，这些结果（i）在结合前将抗原表面与溶剂暴露的蛋白表面区分开来，（ii）支持一种两阶段相互作用机制，该机制允许抗体结合诱导蛋白抗原发生变化，（iii）表明通过改变单个关键残基可显著降低蛋白抗原性，而不破坏其生物活性。
