Differential Hydration of α,ω-Aminocarboxylic Acids in D<sub>2</sub>O and H<sub>2</sub>O
Bibliographic record
Abstract
We report the relative molar sound velocity increments, [ U ], partial molar volumes, V °, expansibilities, E °, and adiabatic compressibilities, K ° S, for a homologous series of eight α,ω-aminocarboxylic acids in D 2 O solution within the temperature range of 18−55 °C. We use the resulting data to estimate the volume, expansibility, and adiabatic compressibility contributions of the component aliphatic (methylene groups) and charged (oppositely charged amino and carboxyl termini) chemical groups. We compare these group contributions with similar group contributions for the same set of α,ω-aminocarboxylic acids in H 2 O (Chalikian, T. V.; Sarvazyan, A. P.; Breslauer, K. J. J. Phys. Chem. 1993, 97, 13017−13026). We use these data to characterize quantitatively the differential hydration properties of charged and hydrophobic groups in D 2 O and H 2 O. Taken together, our results suggest that the hydration properties of hydrophobic and charged groups in D 2 O, as reflected in their volume, expansibility, and compressibility contributions, are measurably distinct from those in H 2 O. Significantly, these volumetric characteristics of the solute hydration differ not only in their absolute values but also in their temperature dependences. Such characteristics should prove useful in developing a better understanding of the role of differential D 2 O/H 2 O hydration in modulating thermal and thermodynamic stability of proteins. In addition, these results represent a further step in building up an empirical database of differential volumetric parameters of protein functional groups in D 2 O and H 2 O. Such a database is required for developing a methodology in which differential volumetric measurements in D 2 O and H 2 O can be employed to gain insight into the amount and chemical nature of solvent-exposed protein groups in the absence of structural information.
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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".