title: In vivo stoichiometry of photorespiratory metabolism.
abstract: Photorespiration is a major light-dependent metabolic pathway that consumes oxygen and produces carbon dioxide. In the metabolic step responsible for carbon dioxide production, two molecules of glycine (equivalent to two molecules of O2) are converted into one molecule of serine and one molecule of CO2. Here, we use quantitative isotopic techniques to determine the stoichiometry of this reaction in sunflower leaves, and thereby the O2/CO2 stoichiometry of photorespiration. We find that the effective O2/CO2 stoichiometric coefficient at the leaf level is very close to 2 under normal photorespiratory conditions, in line with expectations, but increases slightly at high rates of photorespiration. The net metabolic impact of this imbalance is likely to be modest.
authors.affiliation: Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia.
authors.forename: Cyril
authors.initials: C
authors.lastname: Abadie
authors.affiliation: Laboratoire BVpam, EA3061, Université de Lyon/Saint-Etienne, 23 rue du Docteur Michelon, 42000 Saint-Etienne, France.
authors.forename: Edouard R A
authors.initials: ER
authors.lastname: Boex-Fontvieille
authors.affiliation: Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Carroll
authors.affiliation: Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tcherkez
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D006368:Helianthus / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D009587:Nitrogen Isotopes / Q000032:analysis; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012694:Serine / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D002245:Carbon Dioxide; D012694:Serine; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen