Nagaoka I, Yamashita T
Biochim Biophys Acta. 1981 Jun 11;675(1):85-93. doi: 10.1016/0304-4165(81)90072-6.
The subcellular localization of the tuftsin-inactivating activity was studied using guinea-pig polymorphonuclear neutrophils and the following results were obtained. 1. The tuftsin-inactivating activity was present in the membrane fraction but not in the cytosol and the granular fractions. 2. Intact neutrophils inactivated tuftsin rapidly. However, when neutrophils were modified chemically by a poorly permeant reagent, diazotized sulfanilic acid, the tuftsin-inactivating activity decreased significantly without any inhibition of marker enzymes of cytosol, microsome, granules and mitochondria, suggesting that the tuftsin-inactivating activity is located on the plasma membrane as an ecto-enzyme. 3. When neutrophils were modified by diazotized sulfanilic acid at different concentrations, the tuftsin-inactivating activity of neutrophils was inhibited in proportion to the degree of inhibition of the activity of leucine aminopeptidase, an ecto-enzyme. 4, Hydrolysis of L-leucyl-beta-naphthylamide, a synthetic substrate of leucine aminopeptidase, was inhibited competitively by tuftsin. 5. Treatment of neutrophils with serine protease inhibitors affected neither tuftsin-inactivating nor leucine aminopeptidase activity at all, indicating no involvement of serine proteases, which is said to be located on the cell surface membrane, in the tuftsin-inactivation activity of neutrophils. The possibility was deduced from the above results that leucine aminopeptidase may act as a tuftsin-inactivating enzyme.
利用豚鼠多形核中性粒细胞研究了促吞噬素失活活性的亚细胞定位，获得了以下结果。1. 促吞噬素失活活性存在于膜组分中，而不存在于胞质溶胶和颗粒组分中。2. 完整的中性粒细胞能迅速使促吞噬素失活。然而，当中性粒细胞用一种渗透性差的试剂重氮化磺胺酸进行化学修饰时，促吞噬素失活活性显著降低，而对胞质溶胶、微粒体、颗粒和线粒体的标记酶没有任何抑制作用，这表明促吞噬素失活活性作为一种外切酶位于质膜上。3. 当用不同浓度的重氮化磺胺酸修饰中性粒细胞时，中性粒细胞的促吞噬素失活活性与外切酶亮氨酸氨肽酶活性的抑制程度成比例地受到抑制。4. 促吞噬素竞争性抑制亮氨酸氨肽酶的合成底物L-亮氨酰-β-萘酰胺的水解。5. 用丝氨酸蛋白酶抑制剂处理中性粒细胞对促吞噬素失活活性和亮氨酸氨肽酶活性均无影响，这表明位于细胞表面膜上的丝氨酸蛋白酶不参与中性粒细胞的促吞噬素失活活性。从上述结果推断，亮氨酸氨肽酶可能作为一种促吞噬素失活酶起作用。
