Institute of Applied Microbiology, University of Tokyo, Tokyo, Japan.
Plant Physiol. 1970 Feb;45(2):178-82. doi: 10.1104/pp.45.2.178.
With Chlorella ellipsoidea cells, the effect of oxygen was investigated on the products of enhanced dark (14)CO(2) fixation immediately following preillumination in the absence of CO(2). When the reaction mixture was made aerobic by bubbling air (CO(2)-free) throughout preillumination and the following dark (14)CO(2) fixation periods, the initial fixation product was mainly 3-phosphoglyceric acid. When nitrogen gas had been used instead of air, only about one-half of the total radioactivity in the initial fixation products was in 3-phosphoglyceric acid and the rest in aspartic, phosphoenolpyruvic, and malic acids. The percentage distribution of radioactivity incorporated in these initial products rapidly decreased during the rest of the dark period. Concurrent with the decrease in the initial (14)CO(2) fixation products, some increase was observed in the radioactivities of the sugar phosphates. The maximal radioactivity incorporated in sugar mono- and diphosphates accounted for only 10% of total (14)C, under either the aerobic or anaerobic conditions. Under anaerobic conditions most of the (14)C incorporated was eventually transferred to alanine, whereas the main end products under aerobic conditions were aspartate and glutamate. The pattern of (14)CO(2) fixation products was unaffected by the atmospheric condition during the period of preillumination. The preferential flow of the fixed carbon atom to alanine or aspartate depended on the presence or absence of oxygen during the period of dark CO(2) fixation.
用椭圆小球藻细胞，研究了在无二氧化碳的预照光期间，氧气对增强的黑暗（14）CO2 固定产物的影响。当反应混合物通过在预照光和随后的黑暗（14）CO2 固定期间吹入空气（无二氧化碳）使其有氧时，初始固定产物主要是 3-磷酸甘油酸。当使用氮气代替空气时，初始固定产物中只有约一半的总放射性在 3-磷酸甘油酸中，其余的在天冬氨酸、磷酸烯醇丙酮酸和苹果酸中。这些初始产物中放射性掺入的百分比分布在黑暗期的其余时间迅速下降。与初始（14）CO2 固定产物的减少同时，糖磷酸的放射性活性也有所增加。在有氧或无氧条件下，糖单磷酸和二磷酸中掺入的最大放射性仅占总（14）C 的 10%。在无氧条件下，大部分掺入的（14）C 最终被转移到丙氨酸，而有氧条件下的主要终产物是天冬氨酸和谷氨酸。在预照光期间，大气条件对（14）CO2 固定产物的模式没有影响。固定碳原子优先流向丙氨酸或天冬氨酸取决于黑暗 CO2 固定期间是否存在氧气。
