Thioredoxin reductase hydroperoxidase activity toward hydrogen peroxide: molecular mechanisms & dependencies

How nutrients influence it

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Human evidence only

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What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

Whereas hydrogen peroxide was a substrate for the wild-type enzyme, all mutant enzymes, including the truncated form expected in selenium deficiency, lacked hydroperoxidase activity, so selenium is required for the catalytic activities of thioredoxin reductase.
Thioredoxin reductase truncated of its C-terminal SeCys-Gly dipeptide, the form expected in selenium deficiency → Thioredoxin reductase hydroperoxidase activity toward hydrogen peroxide source_derived_draftungraded
Experimental context and source evidence
availability_state
nutrient_deficiency Imported condition classification; unverified.
evidence_span
{"source_cache": "artifacts/hbot-research/10849437.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "13fe79ebefbddac9a76f4cae2e0f1aede8d648b6568adca72f0b0a550e66bc90", "start_char": 0, "end_char": 1374, "text_sha256": "13fe79ebefbddac9a76f4cae2e0f1aede8d648b6568adca72f0b0a550e66bc90"}
experimental_model
Recombinant rat thioredoxin reductase with selenocysteine mutations expressed in E. coli
exposure
SeCys498 replaced by cysteine or serine, and a truncated protein lacking the C-terminal SeCys-Gly dipeptide
limitations
The truncated construct is described by the authors as the form expected in selenium deficiency, which is what links this enzyme chemistry to nutrient supply. It remains a recombinant model, not a measurement in a selenium-deficient animal.
nutrient_topic
Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy
organism
Rat enzyme in a bacterial expression host
plain_language
Without selenium the enzyme can no longer destroy peroxide at all.
primary_references
[hbot-p10849437] Essential role of selenium in the catalytic activities of mammalian thioredoxin reductase revealed by characterization of recombinant enzymes with selenocysteine mutations. (2000). https://pubmed.ncbi.nlm.nih.gov/10849437/ DOI: 10.1074/jbc.m000690200
tissue_or_cell_type
Purified enzyme
trigger_kind
nutrient_deficiency Imported condition classification; unverified.
Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 478–489
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant rat thioredoxin reductase with selenocysteine mutations expressed in E. coli · source_derived_draft · unverified_draft
### hbot-trxr-truncated-no-activity Whereas hydrogen peroxide was a substrate for the wild-type enzyme, all mutant enzymes, including the truncated form expected in selenium deficiency, lacked hydroperoxidase activity, so selenium is required for the catalytic activities of thioredoxin reductase. Condition category: nutrient_deficiency nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: Without selenium the enzyme can no longer destroy peroxide at all. organism: Rat enzyme in a bacterial expression host tissue_or_cell_type: Purified enzyme experimental_model: Recombinant rat thioredoxin reductase with selenocysteine mutations expressed in E. coli limitations: The truncated construct is described by the authors as the form expected in selenium deficiency, which is what links this enzyme chemistry to nutrient supply. It remains a recombinant model, not a measurement in a selenium-deficient animal. exposure: SeCys498 replaced by cysteine or serine, and a truncated protein lacking the C-terminal SeCys-Gly dipeptide evidence_span: {"source_cache": "artifacts/hbot-research/10849437.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "13fe79ebefbddac9a76f4cae2e0f1aede8d648b6568adca72f0b0a550e66bc90", "start_char": 0, "end_char": 1374, "text_sha256": "13fe79ebefbddac9a76f4cae2e0f1aede8d648b6568adca72f0b0a550e66bc90"} [hbot-p10849437] Essential role of selenium in the catalytic activities of mammalian thioredoxin reductase revealed by characterization of recombinant enzymes with selenocysteine mutations. (2000). https://pubmed.ncbi.nlm.nih.gov/10849437/ DOI: 10.1074/jbc.m000690200
Complete structured claim and evidence

Where it participates (unsigned role)

The Ala530 mutant of prostaglandin endoperoxide synthase had both cyclooxygenase and hydroperoxidase activity while the Asn530 mutant lacked cyclooxygenase activity but retained hydroperoxidase activity, establishing that the hydroxyl group of Ser530 is not essential for catalysis or substrate binding and suggesting that a bulky group at position 530, such as that introduced by aspirin acetylation, prevents arachidonate binding to the cyclooxygenase active site.
Cyclooxygenase-1 with asparagine substituted at position 530 → The cyclooxygenase activity of prostaglandin endoperoxide synthase source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/aspirin-research/2144687.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0a66f17b41129423ecb73bf520dad47b666792a6477552db04272474fc79be24", "start_char": 0, "end_char": 1595, "text_sha256": "0a66f17b41129423ecb73bf520dad47b666792a6477552db04272474fc79be24"}
experimental_model
Sequence comparison and site-directed mutagenesis across sheep, mouse and human prostaglandin endoperoxide synthase
exposure
Ser530 replaced with alanine and with asparagine, and tetranitromethane modification with ibuprofen protection
limitations
Extends the single mutant to a pair that differ in bulk. Sequence-based assignment of the heme ligands is inference from similarity, not structure.
nutrient_topic
Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid
organism
Sheep, mouse and human enzyme
plain_language
Swap in a small residue and the enzyme is fine; swap in a bigger one and the cyclooxygenase half stops.
primary_references
[asa-p2144687] Structure-function relationships in sheep, mouse, and human prostaglandin endoperoxide G/H synthases. (1990). https://pubmed.ncbi.nlm.nih.gov/2144687/
tissue_or_cell_type
Recombinant enzyme
Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 104–115
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Sequence comparison and site-directed mutagenesis across sheep, mouse and human prostaglandin endoperoxide synthase · source_derived_draft · unverified_draft
### asa-bulk-not-identity The Ala530 mutant of prostaglandin endoperoxide synthase had both cyclooxygenase and hydroperoxidase activity while the Asn530 mutant lacked cyclooxygenase activity but retained hydroperoxidase activity, establishing that the hydroxyl group of Ser530 is not essential for catalysis or substrate binding and suggesting that a bulky group at position 530, such as that introduced by aspirin acetylation, prevents arachidonate binding to the cyclooxygenase active site. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: Swap in a small residue and the enzyme is fine; swap in a bigger one and the cyclooxygenase half stops. organism: Sheep, mouse and human enzyme tissue_or_cell_type: Recombinant enzyme experimental_model: Sequence comparison and site-directed mutagenesis across sheep, mouse and human prostaglandin endoperoxide synthase limitations: Extends the single mutant to a pair that differ in bulk. Sequence-based assignment of the heme ligands is inference from similarity, not structure. exposure: Ser530 replaced with alanine and with asparagine, and tetranitromethane modification with ibuprofen protection evidence_span: {"source_cache": "artifacts/aspirin-research/2144687.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0a66f17b41129423ecb73bf520dad47b666792a6477552db04272474fc79be24", "start_char": 0, "end_char": 1595, "text_sha256": "0a66f17b41129423ecb73bf520dad47b666792a6477552db04272474fc79be24"} [asa-p2144687] Structure-function relationships in sheep, mouse, and human prostaglandin endoperoxide G/H synthases. (1990). https://pubmed.ncbi.nlm.nih.gov/2144687/
Complete structured claim and evidence

The events it takes part in

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Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

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Open hypotheses

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Thioredoxin reductase hydroperoxidase activity toward hydrogen peroxide