Demarquoy J, Fairand A, Gautier C, Vaillant R
Laboratoire d'Endocrinologie, Université de Haute Normandie, Faculté des Sciences, Mont Saint Aignan, France.
Mol Cell Biochem. 1994 Jul 27;136(2):145-55. doi: 10.1007/BF00926075.
Argininosuccinate synthetase (AS) is the third enzyme in ureogenesis, it catalyses the reaction of condensation of citrulline and aspartate into argininosuccinate. In the present report, we described the first characterization of AS within the outer membrane of rat liver mitochondria. Mitochondria-associated AS displayed the same kinetic characteristics as the cytoplasmic enzyme, but was found to be thermostable while cytoplasmic AS was not. The evolution of the co-location of AS was analyzed during ontogenesis. Total AS activity increased throughout rat fetal development. Simultaneously, the subcellular distribution of the enzyme has changed. AS activity was mainly mitochondrial in fetal and new-born liver liver and cytoplasmic in adult rat liver. The variation in subcellular distribution of AS may be due to the dramatic changes in hormonal levels that occur during this period. The role of corticosteroid and pancreatic hormones was studied. During fetal period, corticosteroid hormones induced an increase in mitochondria-associated AS activity. This was prevented by insulin. Glucagon did not modify total AS activity but reduced mitochondrial AS activity, meanwhile, a comparable increase in cytoplasmic AS activity was observed. One may hypothesize that glucagon may participate in the transfer of mitochondrial enzyme into the cytosol.
精氨琥珀酸合成酶（AS）是尿素生成过程中的第三种酶，它催化瓜氨酸和天冬氨酸缩合生成精氨琥珀酸的反应。在本报告中，我们描述了大鼠肝线粒体外膜中AS的首次特性鉴定。与线粒体相关的AS表现出与胞质酶相同的动力学特征，但发现其具有热稳定性，而胞质AS则不具有。在个体发育过程中分析了AS共定位的演变。在大鼠胎儿发育过程中，总AS活性增加。同时，该酶的亚细胞分布发生了变化。在胎儿和新生大鼠肝脏中，AS活性主要在线粒体中，而在成年大鼠肝脏中则在胞质中。AS亚细胞分布的变化可能是由于在此期间激素水平的显著变化。研究了皮质类固醇和胰腺激素的作用。在胎儿期，皮质类固醇激素诱导与线粒体相关的AS活性增加。胰岛素可阻止这种增加。胰高血糖素不会改变总AS活性，但会降低线粒体AS活性，同时，观察到胞质AS活性有类似的增加。有人可能会推测，胰高血糖素可能参与了线粒体酶向胞质溶胶的转移。
