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通过胰蛋白酶偶联的Ｓｅｐｈａｒｏｓｅ４Ｂ亲和柱，从苦豆子种子中分离纯化出一种胰蛋白酶抑制剂（ＳＡＴＩ）。该抑制剂在１２％的ＳＤＳ－聚丙烯酰胺凝胶电泳中显示单一蛋白带，是由一条Ｎ端为丙氨酸的多肽链组成，分子量为１８ｋＤ，等电点为９．３。结果还显示，抑制剂对胰蛋白酶的摩尔抑制比为１∶２，用氨基酸修饰法，进一步证明其两个活性中心分别是精氨酸和赖氨酸的残基。抗棉蚜的饲喂试验结果表明，该抑制剂对棉蚜有较强的抗性，饲喂１２０小时的半致死浓度为８７．２ｍｇ／Ｌ，半致死量约为（３２头蚜虫）６．７９６μｇ。
A trypsin inhibitor (SATI) was isolated and purified from Sophora alopecuroides seeds by trypsin-conjugated Sepharose 4B affinity column. The inhibitor shows a single protein band on a 12% SDS-polyacrylamide gel electrophoresis and consists of a polypeptide chain with an N-terminal alanine, a molecular weight of 18 kD and an isoelectric point of 9.3. The results also showed that the molar inhibition ratio of inhibitor to trypsin was 1: 2. Using amino acid modification method, it was further proved that the two active centers were residues of arginine and lysine respectively. The feeding test against cotton aphid showed that the inhibitor had stronger resistance to cotton aphid, with a lethal concentration of 87.2 mg / L at 120 hours and a lethal concentration of about 32 aphids. 796 μg.