Dietl T, Tschesche H
Eur J Biochem. 1975 Oct 15;58(2):453-60. doi: 10.1111/j.1432-1033.1975.tb02392.x.
A basic proteinase inhibitor, isoinhibitor K, was purified by SE-Sephadex C-25 column chromatography from the mixture of acid-stable and heat-stable isoinhibitors of the snail (Helix pomatia). Isoinhibitor K is homogeneous in polyacrylamide gel, cellulose acetate and polyacrylamide-dodecylsulfate electrophoresis. From the electrophoretic mobility in dodecylsulfate-polyacrylamide gel and apparent molecular weight of 6500 +/- 200 was estimated. From the amino acid composition the inhibitor consists of 58 amino acid residues. It contains three disulfide bridges, a C-terminal valine and a lysine residue at the reactive site. Isoinhibitor K inhibits the enzymes: bovine trypsin and chymotrypsin, porcine plasmin and pancreatic kallikrein, the trypsin-like component of Streptomyces griseus proteinase-pronase E, and fungi proteinase K from Tritirachium album Limber, which is only inhibited very slightly in contrast to the effect of the mixture of isoinhibitors. The inhibitory effect of isoinhibitor K against these enzymes is compared to that of the mixture or of other isoinhibitors. The following enzymes are not inhibited by isoinhibitor K: Aspergillus proteinase P and alkaline bacillus proteinase 2231 (Röhm), which both are inhibited by the mixture of isoinhibitors. Porcine elastase, bacterial proteinase N (M) (Röhm), and a trypsin-like proteinase from wheat are not inhibited, porcine acrosin and porcine serum kallikrein only to a very minor extent by the mixture of isoinhibitors. Reactive-site peptide-bond cleavage during inhibition could not be detected. Thus, the inhibitory behaviour is just as broad in specificity and as unusual as that of the trypsin-kallikrein inhibitor (Kunitz) from bovine organs. The N-terminus is blocked by pyroglutamic acid. Isoinhibitor K is the main component of the isoinhibitors secreted into the mucus and amounts to 35-40% of the mixture.
一种碱性蛋白酶抑制剂，异抑制剂K，通过SE - Sephadex C - 25柱色谱法从蜗牛（Helix pomatia）的酸稳定和热稳定异抑制剂混合物中纯化得到。异抑制剂K在聚丙烯酰胺凝胶、醋酸纤维素和聚丙烯酰胺 - 十二烷基硫酸盐电泳中均表现为单一成分。根据十二烷基硫酸盐 - 聚丙烯酰胺凝胶中的电泳迁移率，估计其表观分子量为6500±200。从氨基酸组成来看，该抑制剂由58个氨基酸残基组成。它含有三个二硫键、一个C末端缬氨酸和一个位于活性位点的赖氨酸残基。异抑制剂K可抑制以下酶：牛胰蛋白酶和胰凝乳蛋白酶、猪纤溶酶和胰激肽释放酶、灰色链霉菌蛋白酶 - 链霉蛋白酶E的类胰蛋白酶成分以及来自特异腐质霉的真菌蛋白酶K，与异抑制剂混合物的作用相比，真菌蛋白酶K仅受到非常轻微的抑制。将异抑制剂K对这些酶的抑制作用与混合物或其他异抑制剂的抑制作用进行了比较。异抑制剂K不抑制以下酶：曲霉蛋白酶P和碱性芽孢杆菌蛋白酶2231（罗姆公司），这两种酶均受异抑制剂混合物抑制。猪弹性蛋白酶、细菌蛋白酶N（M）（罗姆公司）以及来自小麦的一种类胰蛋白酶均不受抑制，猪顶体蛋白酶和猪血清激肽释放酶仅受到异抑制剂混合物非常轻微的抑制。在抑制过程中未检测到活性位点肽键的断裂。因此，其抑制行为在特异性方面与牛器官中的胰蛋白酶 - 激肽释放酶抑制剂（库尼茨）一样广泛且不同寻常。N末端被焦谷氨酸封闭。异抑制剂K是分泌到黏液中的异抑制剂的主要成分，占混合物的35 - 40%。
