Bibliographic record
Abstract
The first complete mechanistic analysis of halide ion oxidation by a peroxidase was that of iodide oxidation by horseradish peroxidase. It was shown conclusively that a two-electron oxidation of iodide by compound I was occurring. This implied that oxygen atom transfer was occurring from compound I to iodide, forming hypoiodous acid, HOI. Searches were conducted for other two-electron oxidations. It was found that sulfite was oxidized by a two-electron mechanism. Nitrite and sulfoxides were not. If a competing substrate reduces some compound I to compound II by the usual one-electron route, then compound II will compete for available halide. Thus compound II oxidizes iodide to an iodine atom, I*, although at a slower rate than oxidation of I by compound I. An early hint that mammalian peroxidases were designed for halide ion oxidation was obtained in the reaction of lactoperoxidase compound II with iodide. The reaction was accelerated by excess iodide, indicating a co-operative effect. Among the heme peroxidases, only chloroperoxidase (for example from Caldariomyces fumago) and mammalian myeloperoxidase are able to oxidize chloride ion. There is not yet a consensus as to whether the chlorinating agent produced in a peroxidase-catalyzed reaction is hypochlorous acid (HOCl), enzyme-bound hypochlorous acid (either Fe-HOCl or X-HOCl where X is an amino acid residue), or molecular chlorine Cl2. A study of the nonenzymatic iodination of tyrosine showed that the iodinating reagent was either HOI or I2. It was impossible to tell which species because of the equilibria: [reaction: see text] The same considerations apply to product analysis of an enzyme-catalyzed reaction. Detection of molecular chlorine Cl2 does not prove it is the chlorinating species. If Cl2 is in equilibrium with HOCl then one cannot tell which (if either) is the chlorinating reagent. Examples will be shown of evidence that peroxidase-bound hypochlorous acid is the chlorinating agent. Also a recent clarification of the mechanism of reaction of myeloperoxidase with hydrogen peroxide and chloride along with accurate determination of the elementary rate constants will be discussed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".