目的  验证优化的α₁-抗胰蛋白酶（α₁-antitrypsin，α₁-AT）生物活性测定方法。方法  用发色底物法测定α₁-AT活性，以牛胰蛋白酶替换冻干正常人血清来优化先前建立的方法，验证优化方法的准确性、重复性，并观察不同物质对优化方法的影响。结果  优化方法在胰蛋白酶质量浓度为0.01~0.05 g/L时线性关系良好，相关系数>0.99。优化方法具有良好的准确性和重复性，当采用优化方法测定质量浓度为0.01、0.03、0.05 g/L胰蛋白酶时，胰蛋白酶的回收率分别为99.33%、94.44%和92.67%，变异系数分别为3.79%、1.66%和1.02%。在一定范围内，聚乙二醇、蔗糖、枸橼酸钠、人白蛋白浓度变化对优化方法测定α₁-AT生物活性没有影响。 结论  以牛胰蛋白酶作为参考标准品的优化α₁-AT生物活性测定方法可用于α₁-AT制备工艺中的常规质量控制。

 Objective  To validate an optimized method for determination of α₁-antitrypsin (α₁-AT) activity. Methods  The chromogenic substrate method was used for determination of α₁-AT activity. The previous established method was optimized by substitution of bovine trypsin for lyophilized normal human serum as reference standard. The accuracy and repeatability of the optimized method were validated, and effects of different substances on the optimized method were observed. Results  When trypsin concentrations were in a range of 0.01-0.05 g/L, the optimized method showed a good linearity, and the correlation coefficient was >0.99. The optimized method had a good accuracy and repeatability. When 0.01, 0.03 and 0.05 g/L trypsin were detected by the optimized method, recovery rates of trypsin were 99.33%, 94.44% and 92.67% and the variable coefficients were 3.79%, 1.66% and 1.02%, respectively. Concentration changes of polyethylene glycol, sucrose, sodium citrate and human albumin in a certain range did not influence determination of α₁-AT activity by the optimized method . Conclusion  The optimized method for determination of α₁-AT activity with bovine trypsin as reference standard can be used for the routine quality control in α₁-AT preparation process.