Department of Biology, Brandeis University, Waltham, Massachusetts 02154.
Plant Physiol. 1974 Feb;53(2):136-9. doi: 10.1104/pp.53.2.136.
The ability of intact spinach (Spinacia oleracea) chloroplast preparations to catalyze CO(2) fixation and photophosphorylation was examined. Under conditions optimal for CO(2) fixation, only poor photophosphorylation was observed. Conditions optimal for photophosphorylation were found to be highly inhibitory to the CO(2)-fixing capacity of the intact chloroplast preparation.A method for following the activity of phosphoribulokinase in the intact chloroplast preparation was developed, and conditions for optimal activity were defined. The enzyme was found to be activated 2- to 4-fold by preillumination with a half-time of less than 15 seconds. Activation was inhibited by magnesium ions and selectively by inhibitors of photosynthetic electron transport. We concluded that activation was due to the effect of a photoproduced reductant in a site preceding ferredoxin in the electron transport chain. The photoactivated state of the enzyme decayed in the dark with a half-time of about 8 minutes.
研究了完整菠菜（Spinacia oleracea）叶绿体制剂催化 CO2 固定和光合磷酸化的能力。在 CO2 固定的最佳条件下，仅观察到较差的光合磷酸化。发现光合磷酸化的最佳条件对完整叶绿体制剂的 CO2 固定能力具有高度抑制作用。开发了一种用于跟踪完整叶绿体制剂中磷酸核糖激酶活性的方法，并定义了最佳活性的条件。发现该酶通过用半衰期小于 15 秒的半光预照激活 2-4 倍。镁离子和光合作用电子传递抑制剂选择性地抑制激活。我们得出结论，激活是由于电子传递链中位于铁氧还蛋白之前的位点的光产物还原剂的作用。该酶的光激活状态在黑暗中以约 8 分钟的半衰期衰减。
