Butler M, Abood L G
J Membr Biol. 1982;66(1):1-7. doi: 10.1007/BF01868476.
The pattern of fatty acid release from rat synaptic membranes in the presence of phospholipase A2 (Vipera russelli) was compared to that from liposomes comprised of phospholipids. Phospholipase A2 more readily attacked myelin and synaptic membranes than liposomes prepared from total phospholipids derived from myelin. Although hydrolysis of liposomal phospholipids occurred in the absence of added calcium, the presence of 2 mM CaCl2 or 2% bovine serum albumin significantly enhanced the phospholipase attack of liposomes, but not synaptic membranes of myelin. Phospholipase exhibited a marked preference for phospholipids containing docosahexaenoic acid (22:6) in the synaptic membranes, while with liposomes the pattern of released fatty acid reflected the fatty acid composition in the two-position of the phospholipids. Although either calcium or albumin markedly increased the phospholipase hydrolysis of liposomes, neither affected the hydrolysis of synaptic membranes or the pattern of fatty acid release from liposomes. It was concluded that the nonlipid constituents, particularly the proteins, of biomembranes were responsible for the organization of the phospholipids and accounted for the observed differences between liposomes and synaptic membranes with respect to enzymic accessibility.
将存在磷脂酶A2（罗素蝰蛇）时大鼠突触膜中脂肪酸的释放模式与由磷脂组成的脂质体中的脂肪酸释放模式进行了比较。与由髓磷脂衍生的总磷脂制备的脂质体相比，磷脂酶A2更容易攻击髓磷脂和突触膜。尽管在没有添加钙的情况下脂质体磷脂会发生水解，但2 mM CaCl2或2%牛血清白蛋白的存在会显著增强磷脂酶对脂质体的攻击，但不会增强对髓磷脂突触膜的攻击。磷脂酶对突触膜中含有二十二碳六烯酸（22:6）的磷脂表现出明显的偏好，而对于脂质体，释放脂肪酸的模式反映了磷脂二位的脂肪酸组成。尽管钙或白蛋白均显著增加了脂质体的磷脂酶水解，但两者均未影响突触膜的水解或脂质体脂肪酸的释放模式。得出的结论是，生物膜的非脂质成分，特别是蛋白质，负责磷脂的组织，并解释了脂质体和突触膜在酶可及性方面观察到的差异。
