Backbone Dynamics of Green Fluorescent Protein and the Effect of Histidine 148 Substitution
Bibliographic record
Abstract
Green fluorescent protein (GFP) and its mutants have become valuable tools in molecular biology. GFP has been regarded as a very stable and rigid protein with the beta-barrel shielding the chromophore from the solvent. Here, we report the 15N nuclear magnetic resonance (NMR) studies on the green fluorescent protein (GFPuv) and its mutant His148Gly. 15N NMR relaxation studies of GFPuv show that most of the beta-barrel of GFP is rigid on the picosecond to nanosecond time scale. For several regions, including the first alpha-helix and beta-sheets 3, 7, 8, and 10, increased hydrogen-deuterium exchange rates suggest a substantial conformational flexibility on the microsecond to millisecond time scales. Mutation of residue 148 located in beta-sheet 7 is known to have a strong impact on the fluorescence properties of GFPs. UV absorption and fluorescence spectra in combination with 1H-15N NMR spectra indicate that the His148Gly mutation not only reduces the absorption of the anionic chromophore state but also affects the conformational stability, leading to the appearance of doubled backbone amide resonances for a number of residues. This suggests the presence of two conformations in slow exchange on the NMR time scale in this mutant.
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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".