Huang K, Lauridsen E, Clausen J
Department of Chemistry, Huazhong University of Science and Technology, Wuhan, P.R. China.
Biol Trace Elem Res. 1994 Oct-Nov;46(1-2):91-102. doi: 10.1007/BF02790070.
Polyunsaturated fatty acids (PUFAs) occur in phospholipids of synapses of central nervous system (CNS). PUFAs may thus determine the fluidity of synaptosomal membranes and regulate neuronal transmission. It was therefore tempting to suggest an oxidative system in CNS protecting the membrane function, e.g., glutathione peroxidase (GSH-Px). In order to trace GSH-Px Wistar rats were loaded with 4800 kBq of 75Se sodium selenite. By means of gradient ultracentrifugation, particulate fractions of CNS were isolated and radioactivity as well as selenium dependent GSH-Px were estimated. The following data were obtained: 1. All fractions (myelin, synaptic vesicles, synaptosomes, mitochondria, and microsomes) contained 75Se. 2. After acetone precipitation of GSH-Px activity, fractionation on Sephadex G-150 revealed in all particulate fractions at least two peaks of radioactivity with GSH-Px activity. 3. The two GSH-Px peaks from the Sephadex filtration were freeze dried and applied on a hydrophobic T-gel column and eluted with decreasing molarity of ammonium sulfate from 1.5 to 0.05M. The first Sephadex peak with GSH-Px activity from myelin and the second peak with GSH-Px activity from synaptic vesicles could now be resolved into two different fractions of radioactivity on the T-gel. The remaining Sephadex G-150 peaks could only be resolved into one peak of radioactivity. 4. SDS-polyacrylamide gel electrophoresis of the T-gel peaks from all fractions showed a protein band with a mobility identical with that of human erythrocyte GSH-Px. The T-gel elution of myelin, synaptic vesicles and mitochondria gave rise to nearly pure CNS GSH-Px activity. The data presented support the idea that CNS fractions have membrane bound GSH-Px activity that may function as protecting enzymes towards oxidative stress in the brain.
多不饱和脂肪酸（PUFAs）存在于中枢神经系统（CNS）突触的磷脂中。因此，PUFAs可能决定突触体膜的流动性并调节神经传递。因此，人们很容易推测中枢神经系统中存在一种保护膜功能的氧化系统，例如谷胱甘肽过氧化物酶（GSH-Px）。为了追踪GSH-Px，给Wistar大鼠注射了4800 kBq的75Se亚硒酸钠。通过梯度超速离心分离中枢神经系统的颗粒部分，并估计放射性以及硒依赖性GSH-Px。获得了以下数据：1.所有部分（髓磷脂、突触小泡、突触体、线粒体和微粒体）都含有75Se。2.在丙酮沉淀GSH-Px活性后，在Sephadex G-150上进行分级分离，发现在所有颗粒部分至少有两个具有GSH-Px活性的放射性峰。3.将来自Sephadex过滤的两个GSH-Px峰冷冻干燥，应用于疏水T-凝胶柱，并用硫酸铵的摩尔浓度从1.5降至0.05M进行洗脱。现在，来自髓磷脂的具有GSH-Px活性的第一个Sephadex峰和来自突触小泡的具有GSH-Px活性的第二个峰可以在T-凝胶上分离成两个不同的放射性部分。其余的Sephadex G-150峰只能分离成一个放射性峰。4.所有部分的T-凝胶峰的SDS-聚丙烯酰胺凝胶电泳显示出一条蛋白带，其迁移率与人红细胞GSH-Px相同。髓磷脂、突触小泡和线粒体的T-凝胶洗脱产生了几乎纯的中枢神经系统GSH-Px活性。所提供的数据支持这样一种观点，即中枢神经系统部分具有膜结合的GSH-Px活性，其可能作为针对大脑氧化应激的保护酶发挥作用。
