Département de Biologie, Service de Radioagronomie, Centre d'Etudes Nucléaires de Cadarache, B.P. No. 1, F-13115, Saint-Paul-lez-Durance, France.
Planta. 1974 Jun;118(2):91-100. doi: 10.1007/BF00388386.
By placing leaf segments first in CO2 in the dark, then in pure nitrogen either in the dark and afterwards in the light or immediately in the light, the existence of internal CO2 pools which can be used for photosynthesis had been demonstrated. In Zea mays L. there are two such pools: one which in the absence of any energy source is short-lived (t1/2 ca. 2 min), and another which is relatively long-lived (t1/2 ca. 50 min).Under different oxygen concentrations the level of the short-lived CO2 pool exibited a parallel variation with the level of aspartic acid. Only a fraction of the total aspartic acid (60%) constituted the active pool, the quantity of which was equal to the short-lived CO2. In the absence of O2 but under far-red irradiation (maximum 740 nm), a net synthesis of aspartic acid was observed; its extent depended on the intensity of the light.The similarity in the response to O2 and to long-wavelength irradiation suggests that aspartate synthesis is regulated by ATP, the high-energy compound common to both oxidative and cyclic phosphorylations. The formation of aspartic acid observed in the dark under N2+1% CO2 immediately following illumination under pure N2 suggests use of ATP accumulated in the preceding light period, in aspartate synthesis.Even though Zea mays is predominantly a "malate former", it appears that aspartate must also be considered as a readily available donor of CO2 since, when aspartate is present, O2 release is always immediate while, when it is not, O2 release is delayed.
通过先将叶片片段置于黑暗中的二氧化碳中，然后置于纯氮中，无论是在黑暗中还是之后在光下，或者立即在光下，可以证明存在可用于光合作用的内部二氧化碳库。在玉米中，有两个这样的库：一个在没有任何能源的情况下是短暂存在的（t1/2 约为 2 分钟），另一个则相对持久（t1/2 约为 50 分钟）。在不同的氧气浓度下，短暂存在的二氧化碳库的水平与天冬氨酸的水平表现出平行变化。只有一部分总天冬氨酸（60%）构成了活跃的库，其数量与短暂存在的二氧化碳相等。在没有氧气但远红光照射下（最大 740nm），观察到天冬氨酸的净合成；其程度取决于光的强度。对氧气和长波长照射的反应相似表明，天冬氨酸的合成受 ATP 调节，ATP 是氧化和循环磷酸化都共有的高能化合物。在纯氮下光照后紧接着在 N2+1%CO2 下的黑暗中观察到的天冬氨酸的形成表明，在先前的光照期间积累的 ATP 用于天冬氨酸的合成。尽管玉米主要是“苹果酸形成者”，但似乎天冬氨酸也必须被视为可随时获得的二氧化碳供体，因为当存在天冬氨酸时，O2 的释放总是立即发生，而当不存在天冬氨酸时，O2 的释放则会延迟。
