Odani S, Ikenaka T
J Biochem. 1978 Mar;83(3):747-53. doi: 10.1093/oxfordjournals.jbchem.a131968.
Soybean Bowman-Birk inhibitor, a double-headed inhibitor of trypsin and alpha-chymotrypsin, was treated with cyanogen bromide and then pepsin to yield two inhibitory active fragments. Structural investigation showed that one of the fragments was derived from the trypsin inhibitory domain and the other from the chymotrypsin inhibitory domain of the inhibitor. In contrast to the unusual stability of the native inhibitor, the separated domains were less stable and could be inactivated with excess proteinases. These results suggest that the legume double-headed inhibitors acquired their unusual stability by duplicating an ancestral single-headed structure.
大豆鲍曼-伯克抑制剂是一种胰蛋白酶和α-糜蛋白酶的双头抑制剂，用溴化氰处理后再用胃蛋白酶处理，得到两个具有抑制活性的片段。结构研究表明，其中一个片段来源于抑制剂的胰蛋白酶抑制结构域，另一个来源于糜蛋白酶抑制结构域。与天然抑制剂不同寻常的稳定性相反，分离出的结构域稳定性较差，并且会被过量的蛋白酶灭活。这些结果表明，豆科植物的双头抑制剂通过复制祖先的单头结构而获得了不同寻常的稳定性。
