Hydration (H<sub>2</sub>O and D<sub>2</sub>O) Dictates the Stabilities and Conformational Entropy of Transthyretin Tetramers
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Transthyretin (TTR) is a 56 kDa tetrameric protein complex that plays a key role in transporting thyroxine and retinol. Despite its important biological role, TTR exhibits adverse effects, including disassembly into monomers, dimers, and trimers that then aggregate into disease-causing oligomers and fibrils. Hydration (referring to H 2 O or D 2 O) has been shown to have strong effects on TTR tetramer stabilities; however, probing how perturbation of hydration alters tetramer dynamics and stabilities is challenging. Here, we use variable-temperature (5–50 °C) electrospray ionization and ion mobility-mass spectrometry to better understand the influence of D 2 O and H 2 O hydration on the structures, stabilities, and dynamics of both wild-type TTR and several mutants (TTR L55P, TTR V30M, TTR T119M, and TTR V122I ). Our findings include the following: (i) TTR tetramers in D 2 O have lower average charge states compared to those in H 2 O at temperatures between 5 and 50 °C; (ii) there are fewer disassembly products (monomers and dimers) in D 2 O compared to H 2 O at different temperatures; and (iii) the relative abundances of compact versus extended tetrameric forms are shifted in D 2 O compared to H 2 O. Results from hydrogen–deuterium exchange (HDX) combined with bottom-up proteomics of different TTR mutants are consistent with hydration in β-sheet and interface-forming regions providing tetramer stability. Additionally, HDX combined with bottom-up proteomics indicates that shifts in hydration at the interface are responsible for the observed differences between mutants. Overall, our results show that D 2 O significantly alters the TTR stabilities and conformational entropy, highlighting the important role that hydration plays in protein dynamics.
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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) | 0.002 | 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".