Silver Ion Binding Energies of Amino Acids: Use of Theory to Assess the Validity of Experimental Silver Ion Basicities Obtained from the Kinetic Method
Bibliographic record
Abstract
The complexes of silver ion, Ag +, with the twenty naturally occurring amino acids have been calculated using hybrid density functional theory at the B3LYP/DZVP level. For all of these silver complexes, several possible structures were examined, but as there are remarkable similarities between all the structures at the global minima, only summarized data are reported. All of the complexes, except that with proline, are solvated ions. Amino acids containing only hydrocarbon side chains are bidentate, coordinating through the amino and carbonyl groups and the remaining amino acids (with the exception of proline) are tricoordinate with the same two interactions as in the simpler amino acids and an additional interaction through the side chain. The proline complex contains zwitterionic proline with the Ag + ion attached to the carboxylate anion. Enthalpies (at 298 K) for dissociation of Ag + from the complexes range from 49.3 kcal mol -1 for glycine to 80.4 kcal mol -1 for arginine. Free energies for these reactions are in the range of 40.7 kcal mol -1 for glycine to 70.3 kcal mol -1 for arginine. Comparison of the calculated free energies (relative to that of glycine) with those measured by the kinetic method shows good agreement, with the largest discrepancy being 3.9 kcal mol -1 for aspartic acid. There are some systematic trends with theory giving lower values than experiment for amino acids containing aromatic groups in the side chains (phenylalanine, tryptophan, and tyrosine) and higher values for the four amino acids with carbonyl groups in their side chains (aspartic acid, asparagine, glutamic acid, and glutamine).
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 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".