Kinetic Model for the Reversible Hydration of Carbon Dioxide Catalyzed by Human Carbonic Anhydrase II
Bibliographic record
Abstract
Four variants of the two-step Ping Pong mechanism for the reversible hydration of carbon dioxide to bicarbonate catalyzed by free human carbonic anhydrase II (HCA II) in solutions were derived and their goodness-of-fit to match measured initial hydration rates tested. The pseudo (i.e., no central complex) random Quad Quad Iso Ping Pong mechanism with one transitory complex was retained which implied a possible competitive intermolecular proton transfer step by the CO 2 /HCO 3 − pair with respect to external buffer. The model suggests this role could be emphasized in product inhibition conditions at high bicarbonate/buffer concentration ratios. A 4-parameter kinetic model was derived to complement the existing single- (intra- or intermolecular) limiting-step models for HCA II catalyzed hydration of CO 2 in which were accounted for altogether the enzyme isomerization and CO 2 /HCO 3 − proton transfer via a [CO 2 ]·[HCO 3 − ] coupling, the CO 2 /HCO 3 − proton transfer via [HCO 3 − ] 2 and [CO 2 ]·[HCO 3 − ] 2 couplings, and an enzyme−substrate transitory complex via [CO 2 ]·[HCO 3 − ]·[Buffer] coupling. This model may prove helpful for analysis of CO 2 capture reactor models subject to mixed (intra- or intermolecular) proton-transfer control, intermolecular proton transfer competition by the CO 2 /HCO 3 − pair, and large CO 2 conversions.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.001 | 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".