Sumathi S, Pattabiraman T N
Biochim Biophys Acta. 1979 Jan 12;566(1):115-27. doi: 10.1016/0005-2744(79)90254-7.
A trypsin inhibitor was purified from the tubers of Colocasia antiquorum. The inhibitor acted on bovine trypsin, human trypsin and weakly on bovine chymotrypsin. The inhibitor, which had a molecular weight of 40 000, contained trace amounts of carbohydrates. The purified inhibitor was stable over a pH range of 2.0--12.0 and was more thermostable than the crude preparations. Trinitrobenzene sulphonate treatment resulted in the inactivation of the inhibitor. Chymotrypsin, pepsin and pronase digested the inhibitor. Pretreatment with trypsin at neutral pH resulted in the partial loss of antitryptic activity, whereas treatment at pH 3.7 led to complete inactivation. Evidence for the formation of a trypsin-inhibitor complex at pH 7.6 is provided. During the plant growth, in the early phase (0--40 days) there was a gradual increase in protein content and in antitryptic activity. The middle phase (40--55 days) was characterized by a rapid fall and abolition of the antitryptic activity and a diminution in protein content in the tubers. The immature tubers had low antitryptic activity compared to the mature ones. Mild heat treatment caused a sharp rise in antitryptic activity in the extracts of immature tubers but not with the mature tuber preparations.
从芋的块茎中纯化出一种胰蛋白酶抑制剂。该抑制剂作用于牛胰蛋白酶、人胰蛋白酶，对牛胰凝乳蛋白酶的作用较弱。该抑制剂分子量为40000，含有微量碳水化合物。纯化后的抑制剂在pH 2.0至12.0范围内稳定，且比粗制品更耐热。三硝基苯磺酸盐处理会导致抑制剂失活。胰凝乳蛋白酶、胃蛋白酶和链霉蛋白酶可消化该抑制剂。在中性pH下用胰蛋白酶预处理会导致抗胰蛋白酶活性部分丧失，而在pH 3.7下处理则会导致完全失活。提供了在pH 7.6下形成胰蛋白酶-抑制剂复合物的证据。在植物生长过程中，早期阶段（0至40天）蛋白质含量和抗胰蛋白酶活性逐渐增加。中期阶段（40至55天）的特征是抗胰蛋白酶活性迅速下降并消失，块茎中的蛋白质含量减少。与成熟块茎相比，未成熟块茎的抗胰蛋白酶活性较低。温和热处理会使未成熟块茎提取物中的抗胰蛋白酶活性急剧上升，但成熟块茎制品则不会。
