Uncoupling effect of lipid peroxidation in spinach thylakoids exposed to peroxyl radicals generated by 2,2′-azobis (2-amidinopropane) dihydrochloride
Bibliographic record
Abstract
In this study, we characterized how lipid peroxidation alters the functionality of spinach thylakoids exposed to peroxyl radicals generated by the azo compound 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH). Incubation of thylakoids in the presence of different concentrations (0 to 200 mmol·L–1) of AAPH inhibited the formation of ΔpH (IC50 ≈ 1.5 mmol·L–1) estimated by the quenching of 9-aminoacridine fluorescence (Q9-AA). The Q9-AA inhibition was correlated (R2 = 0.98) to the extent of lipid peroxidation determined by the accumulation of thiobarbituric acid reactive substances. Much higher AAPH concentrations were required to inhibit the maximum (Fv/Fm) and effective (ΔF/Fm′) photochemical efficiencies of photosystem II (IC50 ≈ 120 mmol·L–1 and 50 mmol·L–1, respectively), indicating that moderate lipid peroxidation caused the uncoupling of spinach thylakoids. This was confirmed by the 62% stimulation of the O2 uptake rates measured without the artificial uncoupler NH4Cl when the AAPH concentrations increased from 0 to 20 mmol·L–1, reaching similar values to the rates measured in the presence of NH4Cl. Above 20 mmol·L–1 AAPH, the O2 uptake rates measured with and without NH4Cl declined similarly to the decrease of ΔF/Fm′. These results suggest that the increased H+-leakiness of thylakoid membranes could be one of the primary effects of oxidative stress.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".