胰蛋白酶对苯甲酰-dl-精氨酸-p-硝基酰替苯胺盐酸盐(BAPA)水解的催化作用受到胰蛋白酶抑制剂的抑制效应而使水解反应产物在410 nm波长处的吸收减弱,其减弱程度反映了有关胰蛋白酶抑制剂的活性.基础于此原理建立了测定胰蛋白酶抑制剂活性的紫外分光光度法.用大豆标准品验证了所提出方法的可行性和准确度,10次测定结果的标准偏差值为3.0%.分析了一件大豆样品,10次测定结果的平均值为2 527 TIU/g,RSD值为1.2%.

UV-spectrophotometry was applied to the measurement of trypsin inhibitor activity of soya-bean products,based on the inhibitory effect of trypsin inhibitors on the catalytic action of trypsin on the hydrolysis of benzoyl-dl-arginine-p-nitroanilide hydrochloride (BAPA),the product of which showed an UV-absorption at 410 nm.The magnitude of the decrease of absorbance at 410 nm is a measure of trypsin inhibitor activity.The proposed method was checked for its feasibility and accuracy by standard sample of soyabean containing trypsin inhibitor,giving value of RSD′s (n=10) of 3.0%.In analyzing a substantial soya-bean sample for 10 determinations,an average value of TIU/g obtained was 2 527,with a RSD value of 1.2%.