Fe(III)–Heme Complexes with the Amyloid Beta Peptide of Alzheimer’s Disease: QM/MM Investigations of Binding and Redox Properties of Heme Bound to the His Residues of Aβ(1–42)
Bibliographic record
Abstract
Pursuant to our previous paper [J. Chem. Theory Comput. 2012, 8, 5150-5158], the structures of complexes between Aβ(1-42) and ferriheme (Fe(III)-heme-H2O) were determined by application of Amber and ONIOM(B3LYP/6-31G(d):Amber) methodology. Attachment at each of the three His residues was investigated. As well as direct bonding of the iron to the His residue, bonding is augmented by formation of secondary salt bridges between the carboxylate groups of the heme and positively charged residues of Aβ (at His13, by Lys16 and the N-terminus; at His14, by Lys16; at His6, by Arg5). The results indicate a slight preference for His13 followed by His6 and His14, with the lowest 10 structures lying within 30 kJ mol(-1) of each other. The absolute binding affinities are predicted to be approximately 30-40 kJ mol(-1). Standard reduction potentials (E°) are calculated for various Fe(III)/Fe(II) couples. Regardless of the point of attachment of the heme, E° values are approximately -0.6 V relative to the standard hydrogen electrode.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".