突变体Zα1-抗胰蛋白酶(E342K)积累在内质网(ER)聚合物诱发的肝病的肝细胞，而低水平的循环Zα1-抗胰蛋白酶引起的中性粒细胞弹性蛋白酶抑制损失肺气肿。理想的治疗应防止聚合物的形成，同时保持抑制活性。这里我们使用了单克隆抗体技术识别与Zα1-符合要求的团团员。我们报告一个单克隆抗体的产生(4B12)，体外阻断α1-聚合摩尔比为1:1，导致中性粒细胞弹性蛋白酶增加少量的抑制的化学计量。一个单链抗体(scFv)展示了基于mab4b12序列生成。在ER的表达(scfv4b12 scfv4b12kdel)和沿着分泌途径(scfv4b12)降低细胞内聚合Zα1- 60%。scfv4b12滞留的也增加了Zα1-保留抑制中性粒细胞弹性蛋白酶的分泌。mab4b12公认的不连续的抗原表位可能位于该地区的螺旋A / C / G / H /我似乎通过改变蛋白质的动态而不是优先地结合的原生状态。这种新颖的方法可以揭示新的靶点的小分子干预可能会阻止异常的聚合物转变不会影响Zα1-抗胰蛋白酶的抑制活性。—Ordó?ez, A., Pérez, J., Tan, L., Dickens, J. A., Motamedi-Shad, N., Irving, J. A., Haq, I., Ekeowa, U., Marciniak, S. J., Miranda, E., Lomas，D. A.单链滞留防止Zα1-抗胰蛋白酶的细胞内聚合而使其抗蛋白酶活性。

　　原文

　　A single-chain variable fragment intrabody prevents intracellular polymerization of Z α1-antitrypsin while allowing its antiproteinase activity

　　Abstract

　　Mutant Z α1-antitrypsin (E342K) accumulates as polymers within the endoplasmic reticulum (ER) of hepatocytes predisposing to liver disease, whereas low levels of circulating Z α1-antitrypsin lead to emphysema by loss of inhibition of neutrophil elastase. The ideal therapy should prevent polymer formation while preserving inhibitory activity. Here we used mAb technology to identify interactors with Z α1-antitrypsin that comply with both requirements. We report the generation of an mAb (4B12) that blocked α1-antitrypsin polymerization in vitro at a 1:1 molar ratio, causing a small increase of the stoichiometry of inhibition for neutrophil elastase. A single-chain variable fragment (scFv) intrabody was generated based on the sequence of mAb4B12. The expression of scFv4B12 within the ER (scFv4B12KDEL) and along the secretory pathway (scFv4B12) reduced the intracellular polymerization of Z α1-antitrypsin by 60%. The scFv4B12 intrabody also increased the secretion of Z α1-antitrypsin that retained inhibitory activity against neutrophil elastase. MAb4B12 recognized a discontinuous epitope probably located in the region of helices A/C/G/H/I and seems to act by altering protein dynamics rather than binding preferentially to the native state. This novel approach could reveal new target sites for small-molecule intervention that may block the transition to aberrant polymers without compromising the inhibitory activity of Z α1-antitrypsin.—Ordó?ez, A., Pérez, J., Tan, L., Dickens, J. A., Motamedi-Shad, N., Irving, J. A., Haq, I., Ekeowa, U., Marciniak, S. J., Miranda, E., Lomas, D. A. A single-chain variable fragment intrabody prevents intracellular polymerization of Z α1-antitrypsin while allowing its antiproteinase activity.