Re V M, Thornton R F
Aust J Biol Sci. 1980 Mar;33(1):5-14.
The activity of the enzyme aspartate carbamoyltransferase (ACT; EC 2.1.3.2) was studied in ovine tissues. Hepatic, ileal and duodenal tissues showed higher levels of activity (6-19 units) than skeletal muscle, cardiac muscle, lung, spleen, kidney and rumen wall (2-7 units). Low growth impetus skeletal muscles had higher activity (2.9 units) than high growth impetus muscles (1.8 units) taken from immature sheep but such differences were not present in mature sheep. Refeeding of starved immature and mature sheep resulted in two- to threefold increases in activity of ACT in hepatic, ileal and duodenal tissues. These elevated levels of ACT activity were maintained for considerably longer (100 days in immature and 50 days in mature sheep) than the 30 days required for both groups of sheep to achieve liveweights similar to those of continuously grown animals. The optimum pH for ACT activity from both liver and ileum was between pH 8.5 and 9.2 pH profiles showed that activity of ileal ACT was consistently lower than liver ACT in the pH range 6.0-8.5. Starch-gel electrophoresis indicated only one major band of enzyme activity in both liver and ileum. However, both enzymes migrated to different positions in the gel with ileal ACT being the faster migrating of the enzyme forms.
在绵羊组织中研究了天冬氨酸氨甲酰基转移酶（ACT；EC 2.1.3.2）的活性。肝脏、回肠和十二指肠组织的活性水平（6 - 19单位）高于骨骼肌、心肌、肺、脾脏、肾脏和瘤胃壁（2 - 7单位）。取自未成熟绵羊的低生长动力骨骼肌的活性（2.9单位）高于高生长动力肌肉（1.8单位），但在成熟绵羊中不存在这种差异。对饥饿的未成熟和成熟绵羊重新喂食后，肝脏、回肠和十二指肠组织中ACT的活性增加了两到三倍。这些升高的ACT活性水平维持的时间比两组绵羊达到与持续生长动物相似体重所需的30天长得多（未成熟绵羊为100天，成熟绵羊为50天）。肝脏和回肠中ACT活性的最适pH值在8.5至9.2之间，pH曲线表明在6.0 - 8.5的pH范围内，回肠ACT的活性始终低于肝脏ACT。淀粉凝胶电泳表明肝脏和回肠中均只有一条主要的酶活性带。然而，两种酶在凝胶中迁移到不同位置，回肠ACT是迁移速度较快的酶形式。
