Wiederanders B, Schaper S, Kirschke H
Institute of Biochemistry, Faculty of Medicine, Martin-Luther-University Halle/Wittenberg.
Biomed Biochim Acta. 1989;48(1):23-32.
Cathepsin E (EC 3.4.23.--) has been isolated from rat spleen. The procedure included autolysis at pH 4.2 which was probably the reason why we isolated a polypeptide of Mr 42 kDa instead of 90 kDa. The latter is reported in the literature to be the Mr of native cathepsin E. The enzyme dissociates under reducing conditions in two identical monomers. In our preparation a mechanism different from reduction must be active producing the 42 kDa polypeptide. This enzyme was hard to distinguish from cathepsin D (EC 3.4.23.5.) which shows similar properties such as size, substrate specificity, stability in 6 M urea, and dependence of the activity on pH. The clear distinction between the two enzymes was proven on the basis of immunochemical reactions. Antibodies to both cathepsins, D and E, did not show any crossreaction with the nonrelated antigen.
组织蛋白酶E（EC 3.4.23.--）已从大鼠脾脏中分离出来。该过程包括在pH 4.2下进行自溶，这可能是我们分离出的是42 kDa而非90 kDa的多肽的原因。文献报道天然组织蛋白酶E的分子量为90 kDa。该酶在还原条件下解离为两个相同的单体。在我们的制备过程中，一定有不同于还原的机制在起作用，从而产生了42 kDa的多肽。这种酶很难与组织蛋白酶D（EC 3.4.23.5）区分开来，后者具有相似的特性，如大小、底物特异性、在6 M尿素中的稳定性以及活性对pH的依赖性。基于免疫化学反应证明了这两种酶之间的明显区别。针对组织蛋白酶D和E的抗体均未与无关抗原发生任何交叉反应。
