Ueda H, Kobayashi T, Kishimoto M, Tsutsumi T, Watanabe S, Okuyama H
Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Biochem Biophys Res Commun. 1993 Sep 30;195(3):1272-9. doi: 10.1006/bbrc.1993.2181.
EDTA-insensitive phospholipase A activity hydrolyzing phosphatidylinositol was detected in a bovine brain soluble fraction. This phospholipase A was purified 25-fold by sequential chromatographies of DEAE-Toyopearl, Phenyl-Toyopearl, and Ultrahydrogel 1000. The partially purified EDTA-insensitive phospholipase A showed an apparent molecular mass of 230kDa on an Ultrahydrogel 1000 column in the presence of 0.05% Triton X-100 and a pH optimum at 7.0. The enzyme was highly specific for phosphatidylinositol; phosphatidylethanolamine and phosphatidylcholine were not hydrolyzed significantly. The enzyme activity was characterized as phospholipase A1, and Ca2+ and Mg2+ were not required for its activity. These results indicate the existence of Ca(2+)-independent, phosphatidylinositol-specific metabolism besides those catalyzed by Ca(2+)-dependent phospholipase A2 and Ca(2+)-dependent, phosphatidylinositol-specific phospholipase C.
在牛脑可溶性组分中检测到了能水解磷脂酰肌醇的对乙二胺四乙酸（EDTA）不敏感的磷脂酶A活性。通过DEAE - 东曹珠粒、苯基 - 东曹珠粒和超凝胶1000的连续色谱法，这种磷脂酶A被纯化了25倍。在0.05% Triton X - 100存在的情况下，部分纯化的对EDTA不敏感的磷脂酶A在超凝胶1000柱上显示出表观分子量为230 kDa，最适pH为7.0。该酶对磷脂酰肌醇具有高度特异性；磷脂酰乙醇胺和磷脂酰胆碱未被显著水解。该酶活性被表征为磷脂酶A1，其活性不需要Ca2 +和Mg2 +。这些结果表明，除了由Ca2 +依赖性磷脂酶A2和Ca2 +依赖性磷脂酰肌醇特异性磷脂酶C催化的代谢途径外，还存在不依赖Ca2 +的、磷脂酰肌醇特异性的代谢途径。
