Baek S H, Takayama K, Kudo I, Inoue K, Lee H W, Do J Y, Chang H W
Department of Biochemistry, College of Pharmacy, Yeungnam University, Gyongsan, Korea.
Life Sci. 1991;49(15):1095-102. doi: 10.1016/0024-3205(91)90597-5.
Extracellular phospholipase A2 activity has been identified in pleural fluid of patients with tuberculosis. This enzyme is a calcium requiring protein and has a pH optimum of 10.0. The enzyme was inhibited by the active site-directed histidine reagent, rho-bromophenacyl bromide. Ionic and non-ionic detergents, or the sulfhydryl reagent dithiothreitol, caused loss of enzyme activity. When substrate specificity was tested using 2-[1-14C]linoleoyl phospholipids as substrates, phosphatidyl-ethanolamine was the best substrate, followed by phosphatidylserine and phosphatidylcholine. This phospholipase A2 showed high affinity for heparin, and was recognized by a monoclonal antibody raised against phospholipase A2 from human synovial fluid. These findings suggest that an extracellular phospholipase A2, which may belong to the 14K group II phospholipase A2 family, exists in the pleural fluid of patients with tuberculosis.
在结核病患者的胸腔积液中已鉴定出细胞外磷脂酶A2活性。这种酶是一种需要钙的蛋白质，最适pH值为10.0。该酶被活性位点导向的组氨酸试剂溴代苯甲酰溴抑制。离子和非离子去污剂或巯基试剂二硫苏糖醇会导致酶活性丧失。当使用2-[1-14C]亚油酰磷脂作为底物测试底物特异性时，磷脂酰乙醇胺是最佳底物，其次是磷脂酰丝氨酸和磷脂酰胆碱。这种磷脂酶A2对肝素具有高亲和力，并被针对人滑液中磷脂酶A2产生的单克隆抗体识别。这些发现表明，一种可能属于14K II型磷脂酶A2家族的细胞外磷脂酶A2存在于结核病患者的胸腔积液中。
