马铃薯胰凝乳蛋白酶抑制剂活力的测定

Determination of Potato Chymotrypsin Inhibitor Activity

胰凝乳蛋白酶抑制剂的活力测定对于马铃薯块茎蛋白研究非常重要,特别是对于马铃薯蛋白的分离纯化,本文将会详细阐述马铃薯胰凝乳蛋白酶抑制剂的活力测定方法。本文所描述的方法是以酪蛋白为底物,在275 nm检测波长下采用分光光度法,在存在和不存在抑制剂的情况下,用一定量胰凝乳蛋白酶水解酪蛋白,测定酪蛋白分解产物的生成量。检测结果表明,从马铃薯块茎中提取的粗蛋白溶液其胰凝乳蛋白酶抑制剂活力为98.31 CUI/mg,按另外一种表达方式为82.11μg/mg,即每毫克胰凝乳蛋白酶抑制剂能抑制82.11μg胰凝乳蛋白酶。理论上,每100 g马铃薯块茎所含的胰凝乳蛋白酶抑制剂能抑制147.43 mg胰凝乳蛋白酶的活力。该方法不仅适用于马铃薯胰凝乳蛋白酶抑制剂的活力测定,对其他所有来源的胰凝乳蛋白酶抑制剂活力测定同样适用。

Determination of chymotrypsin inhibitor activity is very important for the study of proteins in potato tubers, particularly for protein separation and purification. In this study, a method to evaluate the activity of a potato-derived chymotrypsin inhibitor was explored. This method was based on the spectrophotometric determination（275 nm） of the hydrolysis products of casein that were produced by a specific concentration of chymotrypsin, in the presence or absence of the inhibitor. The results showed that the chymotrypsin inhibitor activity of a crude protein solution extracted from potato tubers was 98.31 CUI/mg（82.11 μg/mg）. In other words, each milligram of chymotrypsin inhibitor inhibited 82.11 μg chymotrypsin. Theoretically, the chymotrypsin inhibitor content in 100 g potato tubers can inhibit the activity of 147.43 mg chymotrypsin. Thus, this method is suitable to determine the activity of chymotrypsin inhibitors from potatoes and other sources.