Coordination properties of Cu(<scp>ii</scp>) and Ni(<scp>ii</scp>) ions towards the C-terminal peptide fragment -TYTEHA- of histone H4
Bibliographic record
Abstract
In order to reveal more information about the toxicity caused by metals and furthermore their influence to the physiological metabolism of the cell, the hexapeptide model Ac-ThrTyrThrGluHisAla-am representing the C-terminal 71-76 fragment of histone H4 which lies into the nucleosome core, was synthesized. A combined pH-metric and spectroscopic UV-VIS, EPR, CD and NMR study of Ni(II) and Cu(II) binding to the blocked hexapeptide, revealed the formation of octahedral complexes involving imidazole nitrogen of histidine, at pH 5 and pH 7 for Cu(II) and Ni(II) ions respectively. In basic solutions a major square-planar 4 N Ni(II)-complex, adopting a {N(Im), 3N(-)} coordination mode, was formed. In the case of Cu(II) ions, a 3 N complex, involving the imidazole nitrogen of histidine and two deprotonated amide nitrogens of the backbone of the peptide, at pH 7 and a series of 4 N complexes starting at pH 6.5, were suggested. In addition Ni(II)-mediated hydrolysis of the peptide bond-Tyr-Thr was evident following our experimental data.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".