Abstract
To study the mechanism of regulation of chloroplastic glutathione reductase (GR) under photooxidative conditions, GR activity, and the levels of NADPH, GSH and GSSG were measured in wheat chloroplasts under photooxidative light. GR was extremely labile, and the concentrations of GSH and GSSG progressively diminished in chloroplasts prepared without ascorbate. The NADPH level did not significantly change during photooxidative treatment. The addition of 10 mM ascorbate to the incubation medium prevented the decrease of GSH and GSSG and strongly protected GR activity. However, ascorbate had no effect on NADPH-dependent inhibition of the chloroplastic GR purified from wheat leaves. We studied the effect of NADPH, temperature, pH and GSSG on the purified enzyme. The inhibition by NADPH was greatly dependent on temperature and pH. NADPH inhibited GR by around 93% up to pH 7.5, but within a range of 8.0 to 9.5 the inhibition was only marginal. The pH dependence of the NADPH inhibitory effect could be due, at least in part, to different rates in the generation of NADPH-X, a derivative of NADPH which inactivates several pyridin nucleotide dehydrogenases. Furthermore, the NADPH-dependent inhibition was almost completely prevented by GSSG, but not by GSH.
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Claims 12
Claim · model-written summary
GR was extremely labile under photooxidative conditions.
- Taxon
- Wheat
Triticum aestivumt0 - Outcome
- GR was extremely labilee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GR was extremely labile”
t0“Wheat Chloroplastic”
Claim · model-written summary
GSH and GSSG concentrations progressively diminished in chloroplasts prepared without ascorbate.
- Taxon
- wheatTriticum aestivume1
- Treatment
- without ascorbatee0
- Outcome
- concentrations of GSH and GSSGe0
- Direction
- progressively diminishede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concentrations of GSH and GSSG progressively diminished in chloroplasts prepared without ascorbate”
e1“wheat chloroplasts”
Claim · model-written summary
NADPH level did not significantly change during photooxidative treatment.
- Taxon
- wheatTriticum aestivume1
- Treatment
- photooxidative treatmente0
- Outcome
- NADPH levele0
- Direction
- did not significantly changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NADPH level did not significantly change during photooxidative treatment.”
e1“wheat chloroplasts”
Claim · model-written summary
Ascorbate prevented decreases in GSH and GSSG.
- Taxon
- wheatTriticum aestivume1
- Treatment
- 10 mM ascorbatee0
- Outcome
- GSH and GSSGe0
- Direction
- prevented the decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The addition of 10 mM ascorbate to the incubation medium prevented the decrease of GSH and GSSG”
e1“wheat chloroplasts”
Claim · model-written summary
Ascorbate strongly protected GR activity.
- Taxon
- wheatTriticum aestivume1
- Treatment
- 10 mM ascorbatee0
- Outcome
- GR activitye0
- Direction
- strongly protectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“10 mM ascorbate to the incubation medium prevented the decrease of GSH and GSSG and strongly protected GR activity”
e1“wheat chloroplasts”
Claim · model-written summary
Ascorbate had no effect on NADPH-dependent inhibition of purified chloroplastic GR.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- leavese0
- Treatment
- ascorbatee0
- Outcome
- NADPH-dependent inhibition of the chloroplastic GRe0
- Direction
- had no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ascorbate had no effect on NADPH-dependent inhibition of the chloroplastic GR purified from wheat leaves”
Claim · model-written summary
NADPH inhibition of GR depended greatly on temperature and pH.
- Taxon
- wheatTriticum aestivume1
- Treatment
- temperature and pHe0
- Outcome
- inhibition by NADPHe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inhibition by NADPH was greatly dependent on temperature and pH.”
e1“wheat chloroplasts”
Claim · model-written summary
NADPH inhibited GR by around 93% up to pH 7.5.
- Taxon
- wheatTriticum aestivume1
- Treatment
- NADPHe0
- Outcome
- GRe0
- Direction
- inhibitede0
- Value
- around 93%e0
- Qualifier
- up to pH 7.5e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NADPH inhibited GR by around 93% up to pH 7.5”
e1“wheat chloroplasts”
Claim · model-written summary
NADPH inhibition was only marginal at pH 8.0 to 9.5.
- Taxon
- wheatTriticum aestivume1
- Outcome
- inhibitione0
- Direction
- only marginale0
- Qualifier
- 8.0 to 9.5e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“within a range of 8.0 to 9.5 the inhibition was only marginal”
e1“wheat chloroplasts”
Claim · model-written summary
The authors suggest pH-dependent NADPH-X generation may explain pH dependence of NADPH inhibition.
- Taxon
- wheatTriticum aestivume1
- Compound
- NADPH-Xe0
- Outcome
- pH dependence of the NADPH inhibitory effecte0
- Qualifier
- could be due, at least in parte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pH dependence of the NADPH inhibitory effect could be due, at least in part, to different rates in the generation of NADPH-X, a derivative of NADPH which inactivates several pyridin nucleotide dehydrogenases.”
e1“wheat chloroplasts”
Claim · model-written summary
GSSG almost completely prevented NADPH-dependent inhibition.
- Taxon
- wheatTriticum aestivume1
- Treatment
- GSSGe0
- Outcome
- NADPH-dependent inhibitione0
- Direction
- almost completely preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NADPH-dependent inhibition was almost completely prevented by GSSG, but not by GSH”
e1“wheat chloroplasts”
Claim · model-written summary
GSH did not prevent NADPH-dependent inhibition.
- Taxon
- wheatTriticum aestivume1
- Treatment
- GSHe0
- Outcome
- NADPH-dependent inhibitione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NADPH-dependent inhibition was almost completely prevented by GSSG, but not by GSH”
e1“wheat chloroplasts”
The same questions in other papers
ascorbate · molecular: metabolites · Triticum aestivum (wheat)Positive and negative results
1 in the opposite direction
- no effect
glutathione · disease · Triticum aestivum (wheat)Positive and negative results
1 in the opposite direction
- positive
ascorbate · physiology: antioxidant enzymes · Triticum aestivum (wheat)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
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.