A Quadrupole‐Central‐Transition <sup>59</sup>Co NMR Study of Cobalamins in Solution
Bibliographic record
Abstract
Abstract We report the first observation of quadrupole‐central‐transition (QCT) 59Co (I=7/2) NMR signals from three cobalamin (Cbl) compounds (CNCbl, MeCbl, and AdoCbl) dissolved in glycerol/water. Measurements were performed at four magnetic fields ranging from 11.7 to 21.1 T. We found that the 59Co QCT signals observed for cobalamin compounds in the slow motion regime (ω0τC≫1) are significantly narrower than those observed from their aqueous solutions where the molecular tumbling is near the condition of ω0τC≈1. We demonstrated that an analysis of 59Co QCT signals recorded over different temperatures and at multiple magnetic fields allowed determination of both the 59Co quadrupole coupling constant and chemical shift anisotropy for each of the three cobalamins. We successfully applied the 59Co QCT NMR approach to monitor in situ the transformation of CNCbl to its “base off” form in the presence of KCN. We further discovered that, to obtain the maximum QCT signal intensity with the Hahn‐echo sequence, a strong B1 field should be used for the first 90° pulse, but a weak B1 field for the second 180° pulse. The reported 59Co QCT NMR methodology opens up a new direction for studying structure and function of cobalamin compounds and their roles in biological processes.
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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 | 0.000 |
| 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".