Woelk H, Rubly N, Arienti G, Gaiti A, Porcellati G
J Neurochem. 1981 Mar;36(3):875-80. doi: 10.1111/j.1471-4159.1981.tb01675.x.
Exogenously added glycerophosphatides, specifically radioactively labelled either in the 1 or in the 2 position, were used to investigate the occurrence and properties of phospholipase A1 in plasma membranes prepared from neuronal- and glial-enriched fractions of rabbit brain. Phospholipase A1 activity was maximal at pH values ranging between 8.0 and 9.0 for the plasma membranes of both cell types. The enzyme activity was most abundant in the microsomal fraction, with a neuronal/glial ratio of about 2. The plasma membranes displayed about half the enzymic activity of the microsomal fraction, whereas only small amounts of phospholipase A1 were present in the neuronal and glial mitochondria. Investigations on the substrate specificity showed a different pattern for the enzyme of neuronal and glial origin. The release of labelled fatty acids from phosphatidylcholine by the neuronal plasma membrane phospholipase A1 decreased with increasing degree of unsaturation of the fatty acids at the 1 position. The presence of plasmalogens and plasmalogen precursors in the incubation mixture appreciably inhibited the hydrolysis of the corresponding diacyl compounds.
外源性添加的甘油磷脂，特别是在1位或2位进行放射性标记的甘油磷脂，被用于研究从兔脑富含神经元和胶质细胞的组分中制备的质膜中磷脂酶A1的存在和性质。对于这两种细胞类型的质膜，磷脂酶A1活性在pH值8.0至9.0之间达到最大值。该酶活性在微粒体组分中最为丰富，神经元/胶质细胞的比例约为2。质膜显示出约为微粒体组分酶活性一半的活性，而在神经元和胶质细胞线粒体中仅存在少量的磷脂酶A1。对底物特异性的研究表明，神经元和胶质细胞来源的酶具有不同的模式。神经元质膜磷脂酶A1从磷脂酰胆碱释放标记脂肪酸的量随着1位脂肪酸不饱和度的增加而减少。孵育混合物中缩醛磷脂和缩醛磷脂前体的存在显著抑制了相应二酰基化合物的水解。
