Electron Capture Dissociation of Electrosprayed Protein Ions for Spatially Resolved Hydrogen Exchange Measurements
Bibliographic record
Abstract
Mass spectrometry (MS) methods involving gas-phase fragmentation hold considerable promise for analyzing regioselective deuteration patterns of proteins following solution-phase amide hydrogen exchange (HX). However, the general viability of such an approach is questionable due to the possible occurrence of intramolecular hydrogen migration ("scrambling"), which tends to randomize or distort the spatial isotope distribution. Rand et al. (J. Am. Chem. Soc. 2008, 130, 1341-1349) have recently reported the application of electron capture dissociation (ECD) for measuring deuteration patterns of short peptides with very little scrambling by FT-MS. The current work shows that even much larger systems such as the 76-residue protein ubiquitin can be successfully analyzed by ECD following solution-phase HX. The resulting c and z. ion deuteration levels are in remarkable agreement with previous NMR data, demonstrating that the extent of scrambling and/or other gas-phase artifacts is negligible. These results open the door to future experiments on the folding, structure, and dynamics of proteins by HX/ECD-FT-MS.
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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) | 0.000 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".