Di Pisa Margherita, Pascarella Simona, Scrima Mario, Sabatino Giuseppina, Real-Fernández Feliciana, Chelli Mario, Renzi Daniela, Calabrò Antonio, D'Ursi Anna Maria, Papini Anna Maria, Rovero Paolo
Laboratory of Peptide and Protein Chemistry and Biology, University of Florence , I-50019 Sesto Fiorentino, Italy.
J Med Chem. 2015 Feb 12;58(3):1390-9. doi: 10.1021/jm5017126. Epub 2015 Jan 26.
Celiac disease (CD) patients usually present high levels of circulating IgA antibodies directed to different antigens, in particular tissue transglutaminase (tTG), gliadin (Glia), and endomysium. A series of synthetic peptide constructs containing cross-linked tTG and Glia deamidated peptides have been synthesized. Peptides were tested in enzyme-linked immunosorbent assays against celiac disease patients' sera versus normal blood donors, and their conformational features were evaluated by molecular modeling techniques. Four peptides were recognized as epitopes by autoantibodies (IgG class) circulating in CD patients' sera before gluten-free diet. The peptide II, containing Ac-tTG(553-564)-NH2 sequence cross-linked with deamidated Ac-α2-Glia(63-71)-NH2, was able to identify specific disease antibodies with a sensitivity of 50% and a specificity of 94.4%. Structural conformations of the linear fragments Ac-tTG(553-564)-NH2 and Ac-α2-Glia(63-71)-NH2 and the corresponding cross-linked peptide II were calculated by molecular modeling. Results showed that cross-linking is determinant to assume conformations, which are not accessible to the linear fragments.
乳糜泻（CD）患者通常呈现高水平的针对不同抗原的循环IgA抗体，尤其是组织转谷氨酰胺酶（tTG）、麦醇溶蛋白（Glia）和肌内膜。已经合成了一系列含有交联tTG和去酰胺化Glia肽的合成肽构建体。在酶联免疫吸附测定中，针对乳糜泻患者血清与正常献血者血清对这些肽进行了测试，并通过分子建模技术评估了它们的构象特征。在无麸质饮食之前，有四种肽被乳糜泻患者血清中循环的自身抗体（IgG类）识别为表位。包含与去酰胺化的Ac-α2-Glia(63-71)-NH2交联的Ac-tTG(553-564)-NH2序列的肽II能够以50%的敏感性和94.4%的特异性识别特定的疾病抗体。通过分子建模计算了线性片段Ac-tTG(553-564)-NH2和Ac-α2-Glia(63-71)-NH2以及相应的交联肽II的结构构象。结果表明，交联对于呈现线性片段无法获得的构象起着决定性作用。
