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Record W2142333244 · doi:10.1179/135100000101535708

Peroxidase-catalyzed halide ion oxidation

2000· article· en· W2142333244 on OpenAlex
H. Brian Dunford

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.
fundA Canadian funder is recorded on the work.

Bibliographic record

VenueRedox Report · 2000
Typearticle
Languageen
FieldChemistry
TopicVanadium and Halogenation Chemistry
Canadian institutionsUniversity of Alberta
FundersNatural Sciences and Engineering Research Council of Canada
KeywordsChemistryHypochlorous acidIodideLactoperoxidasePeroxidasePhotochemistryInorganic chemistryHorseradish peroxidaseCatalysisHalideReagentChlorideMedicinal chemistryOrganic chemistryEnzyme

Abstract

fetched live from OpenAlex

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.

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesInsufficient payload (model declined to judge)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.175
Threshold uncertainty score0.980

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0210.000

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.

Opus teacher head0.011
GPT teacher head0.241
Teacher spread0.230 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it