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On the effect of heavy water (D2O) on carbon isotope fractionation in photosynthesis

Tcherkez, Guillaume; Farquhar, Graham

Description

Internal conductance to carbon dioxide is a key aspect of leaf photosynthesis although is still not well understood. It is thought that it comprises two components, namely, a gas phase component (diffusion from intercellular spaces to cell walls) and a liquid phase component (dissolution, diffusion in water, hydration equilibrium). Here we use heavy water (D 2O), which is known to slow down CO2 hydration by a factor of nearly three. Using 12C/13C stable isotope techniques and Xanthium...[Show more]

dc.contributor.authorTcherkez, Guillaume
dc.contributor.authorFarquhar, Graham
dc.date.accessioned2015-12-10T22:59:17Z
dc.identifier.issn1445-4408
dc.identifier.urihttp://hdl.handle.net/1885/61017
dc.description.abstractInternal conductance to carbon dioxide is a key aspect of leaf photosynthesis although is still not well understood. It is thought that it comprises two components, namely, a gas phase component (diffusion from intercellular spaces to cell walls) and a liquid phase component (dissolution, diffusion in water, hydration equilibrium). Here we use heavy water (D 2O), which is known to slow down CO2 hydration by a factor of nearly three. Using 12C/13C stable isotope techniques and Xanthium strumarium L. leaves, we show that the on-line carbon isotope discrimination (Δ13C, or Δobs) associated with photosynthesis is not significantly decreased by heavy water, and that the internal conductance, estimated with relationships involving the deviation of Δ13C, decreased by 8-40% in 21% O2. It is concluded that in typical conditions, the CO2-hydration equilibrium does not exert an effect on CO2 assimilation larger than 9%. The carbon isotope discrimination associated with CO2 addition to ribulose-1,5,bisphosphate by Rubisco is slightly decreased by heavy water. This effect is proposed to originate from the use of solvent-derived proton/deuteron during the last step of the catalytic cycle of the enzyme (hydration/cleavage).
dc.publisherCSIRO Publishing
dc.sourceFunctional Plant Biology
dc.subjectKeywords: Carbon dioxide; Enzyme activity; Fractionation; Isotopes; Photosynthesis; Catalytic cycle; Gas phase component; Internal conductance; Stable isotopes; Heavy water; carbon dioxide; carbon isotope; dicotyledon; enzyme activity; isotopic fractionation; photo
dc.titleOn the effect of heavy water (D2O) on carbon isotope fractionation in photosynthesis
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume35
dc.date.issued2008
local.identifier.absfor060705 - Plant Physiology
local.identifier.ariespublicationu9204316xPUB580
local.type.statusPublished Version
local.contributor.affiliationTcherkez, Guillaume, Universite Paris Sud XI (CNRS UMR 8079)
local.contributor.affiliationFarquhar, Graham, College of Medicine, Biology and Environment, ANU
local.description.embargo2037-12-31
local.bibliographicCitation.issue3
local.bibliographicCitation.startpage201
local.bibliographicCitation.lastpage212
local.identifier.doi10.1071/FP07282
dc.date.updated2015-12-10T08:11:28Z
local.identifier.scopusID2-s2.0-42449136116
local.identifier.thomsonID000255228100005
CollectionsANU Research Publications

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