Abstract
The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase displayed near-maximal activity in isolated, intact barley (Hordeum vulgare L. cv. Pennrad) mesophyll protoplasts. The carboxylase deactivated 40 to 50% in situ when protoplasts were dark-incubated 20 minutes in air-equilibrated solutions. Enzyme activity was fully restored after I to 2 minutes of light. Addition of 5 millimolar NaHCO3 to the incubation medium prevented dark-inactivation of the carboxylase. There was no permanent C02-dependent activation of the protoplast carboxylase either in light or dark. Activation of the carboxylase from ruptured protoplasts was not increased significantly by in vitro preincubation with CO2 and Mg2e. In contrast to the enzyme in protoplasts, the carboxylase in intact barley chloroplasts was not fully reactivated by light at atmospheric CO2 levels. The lag phase in carbon assimilation was not lengthened by dark-adapting protoplasts to low CO2 demonstrating that light-activation of the carboxylase was not involved in photosynthetic induction. Irradiance response curves for reactivation of the the carboxylase and for CO2 fixation by isolated barley protoplasts were similar. The above results show that there was a fully reversible light-activation of the carboxylase in isolated barley pi itoplasts at physiologically significant CO2 levels.
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Claims 10
Claim · model-written summary
Ribulose-1,5-bisphosphate carboxylase/oxygenase showed near-maximal activity in isolated intact barley mesophyll protoplasts.
- Taxon
- Barley
.jpg?width=60)
Hordeum vulgaree0 - Material
- Pennrade1
- Organ / stage
- mesophyll protoplastse1
- Outcome
- near-maximal activitye1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Isolated Barley Protoplasts”
e1“displayed near-maximal activity in isolated, intact barley (Hordeum vulgare L. cv. Pennrad) mesophyll protoplasts”
Claim · model-written summary
The carboxylase deactivated by 40 to 50% in situ when barley protoplasts were dark-incubated for 20 minutes in air-equilibrated solutions.
- Taxon
- BarleyHordeum vulgaree0
- Treatment
- dark-incubated 20 minutese1
- Outcome
- carboxylasee1
- Direction
- deactivatede1
- Value
- 40 to 50%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“The carboxylase deactivated 40 to 50% in situ when protoplasts were dark-incubated 20 minutes in air-equilibrated solutions”
Claim · model-written summary
Carboxylase activity was fully restored after 1 to 2 minutes of light.
- Taxon
- BarleyHordeum vulgaree0
- Treatment
- lighte1
- Outcome
- Enzyme activitye1
- Direction
- fully restorede1
- Value
- I to 2 minutese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“Enzyme activity was fully restored after I to 2 minutes of light”
Claim · model-written summary
Adding 5 millimolar NaHCO3 to the incubation medium prevented dark-inactivation of the carboxylase.
- Taxon
- BarleyHordeum vulgaree0
- Treatment
- 5 millimolar NaHCO3e1
- Outcome
- dark-inactivation of the carboxylasee1
- Direction
- preventede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“Addition of 5 millimolar NaHCO3 to the incubation medium prevented dark-inactivation of the carboxylase”
Claim · model-written summary
There was no permanent CO2-dependent activation of the protoplast carboxylase in light or dark.
- Taxon
- BarleyHordeum vulgaree0
- Outcome
- permanent C02-dependent activation of the protoplast carboxylasee1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“There was no permanent C02-dependent activation of the protoplast carboxylase either in light or dark”
Claim · model-written summary
Activation of the carboxylase from ruptured protoplasts was not significantly increased by in vitro preincubation with CO2 and Mg2+.
- Taxon
- BarleyHordeum vulgaree0
- Organ / stage
- ruptured protoplastse1
- Treatment
- in vitro preincubation with CO2 and Mg2ee1
- Outcome
- Activation of the carboxylasee1
- Direction
- not increased significantlye1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“Activation of the carboxylase from ruptured protoplasts was not increased significantly by in vitro preincubation with CO2 and Mg2e”
Claim · model-written summary
In contrast to the enzyme in protoplasts, the carboxylase in intact barley chloroplasts was not fully reactivated by light at atmospheric CO2 levels.
- Taxon
- barleyHordeum vulgaree0
- Organ / stage
- intact barley chloroplastse0
- Treatment
- light at atmospheric CO2 levelse0
- Outcome
- carboxylasee0
- Direction
- not fully reactivatede0
- Comparator
- enzyme in protoplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast to the enzyme in protoplasts, the carboxylase in intact barley chloroplasts was not fully reactivated by light at atmospheric CO2 levels”
Claim · model-written summary
The lag phase in carbon assimilation was not lengthened by dark-adapting protoplasts to low CO2.
- Taxon
- BarleyHordeum vulgaree0
- Treatment
- dark-adapting protoplasts to low CO2e1
- Outcome
- lag phase in carbon assimilatione1
- Direction
- not lengthenede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“The lag phase in carbon assimilation was not lengthened by dark-adapting protoplasts to low CO2”
Claim · model-written summary
Irradiance response curves for carboxylase reactivation and for CO2 fixation by isolated barley protoplasts were similar.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- Irradiance response curvese0
- Direction
- similare0
- Comparator
- CO2 fixatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irradiance response curves for reactivation of the the carboxylase and for CO2 fixation by isolated barley protoplasts were similar”
Claim · model-written summary
The authors conclude that light-activation of the carboxylase is not involved in photosynthetic induction.
- Taxon
- BarleyHordeum vulgaree0
- Outcome
- photosynthetic inductione1
- Qualifier
- light-activation of the carboxylase was not involvede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolated Barley Protoplasts”
e1“demonstrating that light-activation of the carboxylase was not involved in photosynthetic induction”
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See all 18 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.