Weitz J I, Landman S L, Crowley K A, Birken S, Morgan F J
J Clin Invest. 1986 Jul;78(1):155-62. doi: 10.1172/JCI112545.
Leukocyte extracts contain enzymes that digest fibrinogen and release a fibrinopeptide A-containing fragment. This study was undertaken to identify the responsible proteinase and to characterize the fibrinopeptide A-containing fragment so that it could be used as an index of enzyme activity. Both the fibrinogenolytic activity and the release of the fibrinopeptide A-containing fragment mediated by the leukocyte extracts were shown to be due to human neutrophil elastase (HNE) by the following criteria: activity was completely blocked by a specific HNE inhibitor or by adsorbing HNE from the extracts with a monospecific antibody and reconstitution with purified HNE restored the ability to release the fibrinopeptide A-containing fragment. This fragment was not released by a variety of other proteinases or by HNE-inhibitor complexes indicating that, at least with respect to the enzymes tested, it is a specific product of HNE and its release requires the free enzyme. By separating the products of HNE digestion of fibrinogen using high performance liquid chromatography, identifying the immunoreactive fractions and subjecting them to amino acid analysis, the fragment was identified as A alpha 1-21, indicating an HNE cleavage site at the Val(A alpha 21)-Glu(A alpha 22) bond. The mean plasma A alpha 1-21 level was markedly higher in patients with alpha 1-proteinase inhibitor deficiency as compared to healthy controls (0.2 nM vs. 7.9 nM; P less than 0.0001), consistent with increased in vivo HNE activity in these individuals.
白细胞提取物含有能消化纤维蛋白原并释放含纤维蛋白肽A片段的酶。本研究旨在鉴定相关蛋白酶，并对含纤维蛋白肽A的片段进行特性分析，以便将其用作酶活性的指标。通过以下标准表明，白细胞提取物介导的纤维蛋白原分解活性和含纤维蛋白肽A片段的释放均归因于人类中性粒细胞弹性蛋白酶（HNE）：活性被特异性HNE抑制剂完全阻断，或通过用单特异性抗体从提取物中吸附HNE，并用纯化的HNE重构后恢复了释放含纤维蛋白肽A片段的能力。该片段不会被多种其他蛋白酶或HNE抑制剂复合物释放，这表明，至少就所测试的酶而言，它是HNE的特异性产物，其释放需要游离酶。通过使用高效液相色谱法分离HNE消化纤维蛋白原的产物，鉴定免疫反应性组分并对其进行氨基酸分析，该片段被鉴定为Aα1 - 21，表明HNE在Val（Aα21）-Glu（Aα22）键处有切割位点。与健康对照相比，α1 - 蛋白酶抑制剂缺乏患者的血浆Aα1 - 21平均水平明显更高（0.2 nM对7.9 nM；P小于0.0001），这与这些个体体内HNE活性增加一致。
