Ikemoto F, Song G, Tominaga M, Yamamoto K
Department of Pharmacology, Osaka City University Medical School, Japan.
Biochem Biophys Res Commun. 1988 Jun 30;153(3):1032-7. doi: 10.1016/s0006-291x(88)81332-9.
The activity of angiotensin converting enzyme(ACE) in crude extracts of the rat renal cortex was increased when the oxidizing agent diamide was added to the extract. The maximal activity was obtained at concentrations over 1 mM, and the value was twice or more the activity in the absence of the pretreatment. The activity of ACE was also increased by the diamide-pretreatment of the isolated membrane fraction of the renal cortex, thereby indicating that the increase in activity was not due to oxidation of endogenous glutathione (GSH) that may lower the ACE activity, but rather that ACE itself was oxidized. When O2 was included in the extract for 2 h, the ACE activity also increased to about twice the original activity. Lineweaver-Burk plots analysis demonstrated that, after oxidation with diamide and O2, the Vmax was increased but the Km remained unchanged. We conclude that the action of ACE in the kidney functions may differ in relation to oxidation of the tissue.
当向大鼠肾皮质粗提物中添加氧化剂二酰胺时，肾皮质粗提物中血管紧张素转换酶（ACE）的活性会增加。在浓度超过1 mM时可获得最大活性，该值是未进行预处理时活性的两倍或更高。肾皮质分离膜部分经二酰胺预处理后，ACE的活性也会增加，这表明活性增加并非由于内源性谷胱甘肽（GSH）氧化可能降低ACE活性所致，而是ACE本身被氧化。当提取物中加入O₂ 2小时后，ACE活性也增加到约为原来活性的两倍。Lineweaver-Burk图分析表明，经二酰胺和O₂ 氧化后，Vmax增加但Km保持不变。我们得出结论，肾脏中ACE的作用可能因组织氧化而有所不同。
