Claim · model-written summary
Spinach RuBisCO activated with CO2 and Mg2+ showed a two-phase carboxylase reaction, an initial burst of a few minutes followed by a linear phase, under saturating CO2, RuBP and Mg2+.
- Taxon
- Spinach
Spinacia oleraceat0 - Outcome
- two phasese0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleTreatmentComparatorSettingDirectionValueQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The reaction of spinach RuBisCO activated with CO2 and Mg2+ proceeded in two phases, an initial burst for a few minutes and the subsequent linear phase”
t0“Spinach”
Title
Akiho Yokota; Shozaburo Kitaoka Plant and Cell Physiology 1989. doi:10.1093/oxfordjournals.pcp.a077728
Other claims from this paper (12)
- Observation With spinach RuBisCO prepared with polyethylene glycol, the activity in the linear phase was 55% of that in the initial burst.
- Observation Spinach RuBisCO prepared with ammonium sulfate showed a much larger decrease of activity in the linear phase.
- Observation The Euglena RuBisCO enzyme had a linear course of reaction with time for up to 20 minutes.
- Observation The Km for CO2 of beforehand-activated spinach RuBisCO was 20 uM in the initial burst.
- Observation The Km for CO2 of beforehand-activated spinach RuBisCO was 28 uM in the linear phase.
- Observation The Km for CO2 in the linear phase of pre-inactivated spinach RuBisCO was 70 uM.
- Observation When the carboxylase reaction was initiated with inactive enzyme, activity was initially negligible and rose within 5 minutes to the level of the linear phase of the activated enzyme.
- Mechanism The authors conclude that the RuBP concentration was the immediate cause of the two-phasic course of the spinach RuBisCO carboxylase reaction.
- Observation The curvature of the time course was not observed below 35 uM RuBP.
- Observation Spinach RuBisCO required over 88 uM RuBP for the conventional two-phasic course.
- Intervention effect Further increase of the RuBP concentration increased the extent of the curvature but did not make the curvature start sooner after the start of the reaction.
- Observation In the linear phase, dilution of RuBP or its consumption to below 30 uM caused spinach RuBisCO to resume the biphasic reaction course after addition of a high RuBP concentration.