Fraction of all reactions of RuBisCO that are oxygenation (instead of carboxylation) at 25°C

Range ~35 %
Organism Biosphere
Reference Peterhansel C et al., Engineering photorespiration: current state and future possibilities. Plant Biol (Stuttg). 2013 Jul15(4):754-8. doi: 10.1111/j.1438-8677.2012.00681.x. p.754 left columnPubMed ID23121076
Primary Source Sharkey T.D. (1988) Estimating the rate of photorespiration in leaves. Physiologia Plantarum, 73, 147–152. DOI: 10.1111/j.1399-3054.1988.tb09205.x
Comments "Rubisco, the enzyme catalysing carbon dioxide (CO2) fixation during oxygenic photosynthesis, is not completely capable of discriminating between its major substrate CO2 and molecular oxygen (O2). In the current atmosphere containing high amounts of O2 (21%) and still relatively low amounts of CO2 (0.04%), at 25°C approximately 35% of all reactions are oxygenation of ribulose-1,5-bisphosphate (RuBP) instead of carboxylation (primary source)." See Szecowka et al., 2013 PMID 23444331 p.694 right column bottom paragraph:"Rubisco catalyzes a side reaction in which RuBP reacts with O2 to form one molecule of 3PGA and one molecule of 2-phosphoglycollate. Under current atmospheric conditions, in organisms without a C concentrating mechanism, this side reaction occurs at 25% of the rate of the reaction with CO2 (primary source)." Keywords:photosynthesis
Entered by Uri M
ID 111055