Sharkey T D, Seemann J R, Berry J A
Biological Sciences Center, Desert Research Institute, P.O. Box 60220, Reno, Nevada, 89506.
Plant Physiol. 1986 Jul;81(3):788-91. doi: 10.1104/pp.81.3.788.
The regulation of ribulose-1,5-bisphosphate (RuBP) carboxylase (rubisco) activity in Phaseolus vulgaris was studied under moderate CO(2) and high light, conditions in which photosynthesis in C(3) plants can be insensitive to changes in O(2) partial pressure. Steady state RuBP concentrations were higher, the calculated rate of RuBP use was lower and the activation state of rubisco was lower in low O(2) relative to values observed in normal O(2). It is suggested that the reduced activity of rubisco observed here is related to feedback effects which occur when the rate of net CO(2) assimilation approaches the maximum capacity for starch and sucrose synthesis (triose phosphate utilization). The activation state of rubisco was independent of O(2) partial pressure when light or CO(2) was limiting for photosynthesis. Reduced activity of rubisco was also observed at limiting light. However, in this species light dependent changes in the concentration of an inhibitor of rubisco controlled the apparent V(max) of rubisco in low light while changes in the CO(2)-Mg(2+) dependent activation of rubisco controlled the apparent V(max) in high light.
在适度二氧化碳和高光条件下研究了菜豆中1,5 - 二磷酸核酮糖（RuBP）羧化酶（rubisco）的活性调节，在这些条件下C₃植物的光合作用可能对氧气分压的变化不敏感。相对于在正常氧气条件下观察到的值，在低氧条件下稳态RuBP浓度更高，计算出的RuBP利用率更低，rubisco的活化状态更低。有人认为，此处观察到的rubisco活性降低与当净二氧化碳同化速率接近淀粉和蔗糖合成（磷酸丙糖利用）的最大能力时发生的反馈效应有关。当光照或二氧化碳限制光合作用时，rubisco的活化状态与氧气分压无关。在限制光照条件下也观察到rubisco活性降低。然而，在该物种中，rubisco抑制剂浓度的光依赖性变化在低光照下控制了rubisco的表观Vmax，而rubisco的二氧化碳 - 镁离子依赖性活化变化在高光照下控制了表观Vmax。
