Mikhaĭlova A G, Evtiukova N G, Chupova L A, Rumsh L D
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.
Vopr Med Khim. 1998 Jul-Aug;44(4):338-46.
Enteropeptidase inhibitor (DI) was isolated from bovine duodenum during purification of this enzyme. DI was purified by affinity chromatography on immobilised trypsin. DI preparations contain two main components: DI-9 (9 kD) and DI-20 (20 kD). The N-terminal amino acid sequence 1-19 of DI-9 is highly homologous to the Kunitz inhibitor (BPI). Molecular weights of DI-9 and BPI are the same (gel electrophoresis data). Fragment 1-19 of DI-9 differs from the corresponding region of BPI only at the position 17: DI-9 contains Ala-17 instead of Arg in BPI. The homology of N-terminal amino acid sequence 1-25 of DI-20 with the corresponding regions of some phospholipases A2 suggests that this protein is a new intestinal phospholipase A2. Inhibitor DI-9 and phospholipase DI-20 are probably isolated in a common lipoprotein complex. The only earlier known in vitro inhibitor of enteropeptidase, BPI, was localised in vivo in different tissues with this enzyme. In our opinion the Kunitz-type inhibitor DI-9 is, a physiological inhibitor of enteropeptidase.
肠肽酶抑制剂（DI）是在该酶的纯化过程中从牛十二指肠中分离出来的。DI通过固定化胰蛋白酶亲和层析进行纯化。DI制剂包含两个主要成分：DI-9（9 kDa）和DI-20（20 kDa）。DI-9的N端氨基酸序列1-19与库尼茨抑制剂（BPI）高度同源。DI-9和BPI的分子量相同（凝胶电泳数据）。DI-9的1-19片段与BPI的相应区域仅在第17位不同：DI-9在该位置含有丙氨酸-17，而BPI中为精氨酸。DI-20的N端氨基酸序列1-25与一些磷脂酶A2的相应区域的同源性表明该蛋白是一种新的肠磷脂酶A2。抑制剂DI-9和磷脂酶DI-20可能以共同的脂蛋白复合物形式被分离出来。之前唯一已知的肠肽酶体外抑制剂BPI，在体内与该酶定位于不同组织中。我们认为库尼茨型抑制剂DI-9是肠肽酶的一种生理抑制剂。
