The possibility of the double head of leguminous STI(Kunitz) family inhibitors.

1)用常规方法测定了四季豆凝乳蛋白酶抑制因子3(WCI-3)的氨基酸全序列。WCI-3由183个氨基酸残基组成，但在羧基末端是异质性的。WCI-3与STI(Kunitz)家族抑制剂的序列高度同源。2)用猪胰凝乳酶在pH 3.0条件下处理WCI-3。然而，胰凝乳酶只对第一个反应位点(Leu(65)-Ser(66))进行水解。在用几种胰凝乳酶家族酶、弹性酶、枯草杆菌酶、SGPS和SGPB切割WCI-3的第二反应位点的试验中，没有一种酶能切割第二反应位点的肽键。用大豆胰酶抑制剂(Kunitz)(STI)Ti^a进行了类似的研究，结果表明，Ti^a的第二反应中心可能位于Met(84)-Leu(85)或其附近。

1) The complete amino acid sequence of winged bean chymotrypsin inhibitor 3 (WCI-3) was determined by the conventional methods. WCI-3 consisted of 183 amino acid residues, but was heterogeneous in the carboxyl terminal region. The sequence of WCI-3 was highly homologous with those of STI(Kunitz) family inhibitors.2) WCI-3 was treated with porcine chymotrypsin at pH 3.0. Chymotrypsin, however, hydrolyzed only the first reactive site (Leu(65)-Ser(66)). Onthe trial to cleave the second reactive site oF WCI-3 using several chymotrypsin-family enzymes, elastase, subtilisin, SGPS and SGPB, no enzyme could cleave the peptide bond of the second reactive site. The similar studies were done using the soybean trypsin inhibitor (Kunitz) (STI) Ti^a. The results suggested that the second reactive site of Ti^a might be located at or near Met(84)-Leu(85).