不同磷脂和糖脂对莱氏衣原体膜上Mg^（2＋）－ATPase活性的影响

Effect of Phospholipids and Glycolipids on Activity of Mg￣(2+)-ATPaseof A. laidlawii Membranes

莱氏衣原体膜上Ｍｇ^（２＋）－ＡＴＰａｓｅ用ＤＯＣ溶解后，经Ｓｅｐｈａｒｏｓｅ－６Ｂ和ＤＥＡＥ－ＣｅｌｌｕｌｏｓｅＤＥ－５２离子交换柱，得到了部分纯化的Ｍｇ^（２＋）ＡＴＰａｓｅ，并将此ＡＴＰａｓｅ与不同极性头部的磷脂和膜糖脂重组，研究了不同的极性头部的磷脂和膜糖脂对ＡＴＰａｓｅ活性的影响。此酶的活性不依赖酸性磷脂，ＰＧ、ＤＰＧ、大豆磷脂等明显抑制酶活性，中性磷脂ＤＭＰＣ、ＰＥ、ＰＣ则能增加酶活性，其中尤以非双层脂ＰＥ的作用最为明显。从莱氏衣原体膜上提取的糖脂（ＭＧＤＧ，ＤＧＤＧ）单独和ＡＴＰａｓｅ重组时，酶活性增加并不明显，当ＭＧＤＧ和ＤＧＤＧ以等比例混合时，能大大地增加酶活性。这表明Ｍｇ^（２＋）－ＡＴＰａｓｅ的活性很大程度上与磷脂的表面电荷及磷脂的组成相关。

Mg￣(2+)-ATPase had been partly purified from Acholeplasm Laidlawii AIH089membranes by extraction with 1% DOC followed by Separose-6B and DEAE-Cellulose DE52 chromatography. The Mg￣(2+)-ATPase was then successfully reconstituted with a number of different phospholipids and glycolipids using a cholate solubilation and dialysis procedure.The ability of these lipids to support the function of this enzyme was evaluated by their ability to increase the specific activity of the enzyme. The incorporation of the ATPase into liposomes composed of the endogenous membrane glycolipids (MGDG and DGDG), zwitterionic phospholipid (PC) or nonbilayer phospholipid (PE), resulted in full recovery of the enzyme activity. In contrast,anionic phospholipid alone, such as PG, DPG, would cause inhibition to this ATPase. Our results indicated that Mg￣(2+)-ATPase from A. laidlawii membranes is unlike the other ATPase, including Ca￣(2+)-ATPase from sarcoplasmic reticulum; (Na￣+K￣+)ATPase from rabbit brain and H￣+-ATPase from mitochondria membranes, which are dependent on anionic phospholipids rather than zwitterionic phospholipids from their activity.