PLANT PHYSIOLOGY · 1999 · 226 citations · 36 references
Life SciencesPlant BiologyPlant SciencesPhotosynthesisPlant BiochemistryPlant PhysiologyCarbon AssimilationCarbon CycleCarbon Dioxide UtilizationCarbon FixationEnvironmental Responses Of PhotosynthesisPhotosynthetic MetabolismCarbon Concentrating MechanismsCarbon Dioxide Capture By AlgaeCo2 AssimilationCyanobacterial PhotosynthesisPhotosynthetic Carbon FixationPhotosynthetic Carbon MetabolismProductivity Under Elevated Carbon DioxideRubisco Function
The ability of photosynthetic organisms to use CO 2 for photosynthesis depends in part on the properties of Rubisco. Rubisco has a surprisingly poor affinity for CO 2 , probably because it evolved in an atmosphere that had very high CO 2 levels compared with the present atmosphere. In C 3 plants the K m (CO 2 ) of Rubisco ranges between 15 and 25 m. In cyanobacteria Rubisco has an even lower affinity for CO 2 , and the K m (CO 2 ) can be greater than 200 m. In comparison, the concentration of CO 2 in water in equilibrium with air is approximately 10 m. From these numbers it becomes apparent that Rubisco is operating at no more than 30% of its capacity under standard atmospheric conditions. This is one of the reasons that C 3 plants contain such large amounts of Rubisco. Exacerbating this situation is the fact that O 2 is a competitive substrate with respect to CO 2 .
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