Alonso E, García-Pérez M A, Bueso J, Rubio V
Department of Biochemistry and Molecular Biology, Facultad de Medicina, Universidad de Valencia, Spain.
Neurochem Res. 1991 Jul;16(7):787-94. doi: 10.1007/BF00965688.
N-Acetyl-L-glutamate (NAG), the activator of mitochondrial carbamoyl phosphate synthetase (CPS), is demonstrated by several methods, including a new HPLC assay, in the brain of mammals and of chicken. The brain levels of NAG are 200-300 times lower than the levels of N-acetyl-L-aspartate (NAA), and are similar to the levels of NAG in rat liver. The NAG levels in chicken liver are very low. Although NAG is mitochondrial in the liver, it is cytosolic in brain. Using enzyme activity and immuno assays we did not detect CPS in brain (detection limit, 12.5 micrograms/g brain), excluding that brain NAG is involved in citrullinogenesis. The regional distribution of brain NAG differs from that of NAA and resembles that of N-acetyl-L-aspartyl-L-glutamate (NAAG), suggesting that NAG and NAAG are related. NAG might be involved in the modulation of NAAG degradation.
N-乙酰-L-谷氨酸（NAG）是线粒体氨甲酰磷酸合成酶（CPS）的激活剂，通过多种方法，包括一种新的高效液相色谱分析法，在哺乳动物和鸡的大脑中得到证实。大脑中NAG的水平比N-乙酰-L-天冬氨酸（NAA）的水平低200 - 300倍，与大鼠肝脏中NAG的水平相似。鸡肝脏中NAG的水平非常低。虽然NAG在肝脏中是线粒体的，但在大脑中是胞质的。通过酶活性和免疫测定，我们在大脑中未检测到CPS（检测限为12.5微克/克脑），排除了大脑NAG参与瓜氨酸生成的可能性。大脑NAG的区域分布与NAA不同，与N-乙酰-L-天冬氨酰-L-谷氨酸（NAAG）的相似，表明NAG和NAAG有关。NAG可能参与NAAG降解的调节。
