Laboratory of Biochemistry, College of Agriculture, Shimane University, Matsue, Shimane 690, Japan.
Plant Physiol. 1986 Jan;80(1):126-9. doi: 10.1104/pp.80.1.126.
The localization of carbamoylphosphate synthetase (CPSase) and aspartate carbamoyltransferase (ACTase), the first two enzymes of the pyrimidine biosynthetic pathway, in chloroplasts was investigated. In dark-grown radish (Raphanus sativus) seedlings, light induced a prominent increase in CPSase activity, but had little effect on ACTase activity. Both enzymes were found in chloroplasts isolated from radish cotyledons and leaves of spinach (Spinacia oleracea), soybean (Glycine max), and corn (Zea mays). The higher activity of ACTase relative to CPSase is discussed in relation to the instability of carbamoylphosphate, the product of the CPSase, and to the control of pyrimidine synthesis. Based on these results, the function of CPSase and ACTase in chloroplasts is discussed.
我们研究了嘧啶生物合成途径的前两个酶——氨甲酰磷酸合成酶(CPSase)和天冬氨酸氨甲酰转移酶(ACTase)——在叶绿体中的定位。在黑暗中生长的萝卜(Raphanus sativus)幼苗中,光照诱导 CPSase 活性显著增加,但对 ACTase 活性几乎没有影响。从萝卜子叶和菠菜(Spinacia oleracea)、大豆(Glycine max)和玉米(Zea mays)叶片中分离出的叶绿体中均发现了这两种酶。相对 CPSase 而言,ACTase 的活性更高,这与 CPSase 的产物氨甲酰磷酸的不稳定性以及嘧啶合成的调控有关。基于这些结果,我们讨论了 CPSase 和 ACTase 在叶绿体中的功能。