Takaoka M, Shiragami K, Fujino K, Miki K, Miyake Y, Yasuda M, Wang G F, Hisaki K, Matsumura Y, Morimoto S
Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
Biochem Int. 1991 Nov;25(4):697-704.
A neutral proteinase with endothelin (ET)-1 converting activity was identified in cytosol and membrane fractions prepared from rat lung, in a ratio of 1:4, respectively. The membrane-bound proteinase was solubilized by 0.5% 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) with an increase in specific activity, and then was characterized. The solubilized proteinase was capable of converting big ET-1 to ET-1 with an optimum pH of 6.5, and the conversion was dose-dependently suppressed by phosphoramidon (IC50 = 0.5 microM). The molecular mass of the proteinase was estimated to be about 500 kDa by gel filtration in the presence of 0.5% CHAPS. These results indicate that rat lung contains a phosphoramidon-sensitive neutral proteinase catalyzing conversion of big ET-1 to ET-1. The proteinase may be involved in the biosynthetic pathway of ET-1 in the lung and/or the conversion of circulating big ET-1.
在从大鼠肺中制备的胞质溶胶和膜组分中分别以1:4的比例鉴定出一种具有内皮素（ET）-1转化活性的中性蛋白酶。膜结合蛋白酶用0.5%的3-[(3-胆酰胺丙基)二甲基铵]-1-丙烷磺酸盐（CHAPS）溶解，比活性增加，然后对其进行表征。溶解的蛋白酶能够将大ET-1转化为ET-1，最适pH为6.5，磷酰胺素可剂量依赖性地抑制这种转化（IC50 = 0.5 microM）。在0.5% CHAPS存在下通过凝胶过滤估计该蛋白酶的分子量约为500 kDa。这些结果表明大鼠肺中含有一种对磷酰胺素敏感的中性蛋白酶，催化大ET-1转化为ET-1。该蛋白酶可能参与肺中ET-1的生物合成途径和/或循环大ET-1的转化。
