Stockley R A, Afford S C
Clin Sci (Lond). 1983 Oct;65(4):373-81. doi: 10.1042/cs0650373.
The quantification of alpha 1-antitrypsin (alpha 1AT) by standard immunological techniques is altered by interaction of the protein with leucocyte elastase. The results obtained for alpha 1-antitrypsin-leucocyte elastase mixtures in the presence of a functional excess of the inhibitor were relatively accurate for the first 6 h. However, continued incubation for more than 24 h led to a major overestimation of the alpha 1AT as the result of breakdown of the enzyme-inhibitor complex releasing a partially proteolysed form of the inhibitor. In the presence of excess enzyme up to a twofold overestimation of alpha 1AT occurred within 1 h and the degree of overestimation increased with time (up to threefold at 24 h). This was eventually associated with the presence of only a partially proteolysed form of alpha 1AT (mol wt. approximately equal to 50 000). Different results for each sample were obtained when different polyclonal antisera were used to quantify the alpha 1AT. Complete inactivation of alpha 1AT by oxidation resulted in little change in the immunological quantification of the protein. However, further addition of H2O2 led to a progressive underestimation of the alpha 1AT. The effect of physiochemical alteration on the immunological quantification of alpha 1AT by different antisera should be borne in mind for all studies assessing this protein in lung secretions.
通过标准免疫技术对α1 -抗胰蛋白酶（α1AT）进行定量时，该蛋白与白细胞弹性蛋白酶的相互作用会改变定量结果。在抑制剂功能过量的情况下，α1 -抗胰蛋白酶 - 白细胞弹性蛋白酶混合物在前6小时获得的结果相对准确。然而，持续孵育超过24小时会导致α1AT的严重高估，这是由于酶 - 抑制剂复合物分解，释放出部分被蛋白水解的抑制剂形式所致。在酶过量的情况下，1小时内α1AT会出现高达两倍的高估，且高估程度随时间增加（24小时时高达三倍）。这最终与仅存在部分被蛋白水解形式的α1AT（分子量约为50000）有关。当使用不同的多克隆抗血清对α1AT进行定量时，每个样品会得到不同的结果。α1AT通过氧化完全失活后，该蛋白的免疫定量变化不大。然而，进一步添加过氧化氢会导致α1AT逐渐被低估。在所有评估肺分泌物中该蛋白的研究中，都应考虑理化改变对不同抗血清免疫定量α1AT的影响。
